Obsidian: Glass from the Volcano

     As you have probably noticed, I usually don’t break minerals into separate posts. Usually I try to contain all of the information that I know about each mineral, rock, or fossil into one post by condensing my writing or by writing a really long post. That isn’t going to work with obsidian, simply because there is a lot to say about it. That is why I plan to blog about obsidian in three or four posts.
     Obsidian is a kind of natural glass that is made when lava cools so quickly that no crystals can form inside of it. Since no crystals can form in obsidian it is amorphous, meaning that is has no crystal structure. Obsidian is composed mostly of quartz and has the same vitreous luster, but it is lighter and softer than quartz (this is because of the way its molecules are arranged.) Obsidian is often black in color, but it can also be mahogany-colored, golden, dark green, gray, greenish-black, yellow, brown, iridescent, and reddish-brown. Iridescent obsidian is also called “rainbow obsidian.” Obsidian can also contain white crystals of the mineral christobalite that look like snowflakes and is therefore called “snowflake obsidian.” Sometimes the colors mentioned above will mix to form obsidian with swirls and patches of different colors. Obsidian is translucent, but thin pieces can appear to be transparent and thick pieces can appear to be opaque.
     After reading this post (which merely covers the basic facts about obsidian) you can probably see why I had to break obsidian into more than one post!

Kyanite: the Multi-hardness Mineral

     Kyanite, which is also called “cyanite,” “rhaeticite” and “disthene” is a polymorph of a chemical called aluminum silicate. In my post about polymorphs I mentioned that I had a few polymorphous minerals to blog about and now I’ve finally gotten around to it. Pure kyanite is colorless, but most kyanite is sky blue. In fact, the name “kyanite” comes from the Greek word kyanos, which means “blue.” This common blue color comes from impurities such as iron and chromium. Other impurities produce such colors as: orange, brown, gray, pink, yellow, and green and sometimes they display color zoning. Kyanite’s crystals are long and flat and they have sharp edges. Kyanite actually has two different levels of hardness on the Mohs’ Scale. A mineral measuring only a 5 on the Mohs’ Scale will scratch a kyanite crystal if taken from top to bottom, but it will take a mineral measuring 7 or above to scratch it when taken from side to side!
     Kyanite is used to make things like fire brick, brake pads and electrical porcelains for cars, floor and wall tiles, and molds for metal casting. Kyanite is also used as a gemstone. The mineral is found all over the world, but some of the best sources are: Kenya, Zimbabwe, Tanzania, Russia, Switzerland, Ukraine, Brazil, India, the Canadian provinces of Quebec and Manitoba, and much of the United States’ Appalachian Region.
     Kyanite is somewhat or a rarity among minerals. Not because it can’t be found in many places, it’s quite common in that way. No, kyanite is rare because of its properties. After all how many other minerals have different harness values depending on the direction that you scratch them?

Wolfram: an Inventive Mineral Name

     As I was doing some research for my post about hubnerite I came across some information about wolfram. Wolfram is not actually a mineral, but rather a name that was once applied to two different minerals when both were thought to be the same (you can read a little more about this in May 19th’s post Hubnerite: Black Beauty) Despite the fact that wolfram is actually two minerals I would still like to write about it today simply because of the origin of its name. In my post about mineral names I told you that a mineral’s name is often just a description of its properties in another language, usually Latin or Greek. This is the case with the word “wolfram,” but the language used to describe its interesting properties is actually German.
     There is a fascinating story behind the name “wolfram.” About five hundred years ago some tin miners in Germany noticed that some of the rocks that they were smelting with the tin ore caused a nasty froth to form on top of the molten metal, which destroyed some of the tin. They named the stone volfram which is composed of the German words volf which means “wolf” and rahm which means “cream” or “froth,” because of the fact that this cream “devoured the tin like a wolf.”
     During the time that I have spent learning about minerals and their names I have seen names translated to mean things like “cross stone,” “golden leek,” and even “the stone that leafs apart,” but I think that “wolf cream” is the most inventive one that I’ve ever seen!
     P.S. tungsten also used to be called wolfram (this likely has something to do with the fact that tungsten is found in the stone) and it is still known by this name in some countries. That is why tungsten is a W on the periodic table.

Hubnerite: Black Beauty

     Hubnerite is a black mineral whose crystals are flat rectangular prisms. Most of the examples that I’ve seen have front and back faces that are nearly perfect squares, but I’ve also seen a few that are more stretched out. Despite the way that I described it above, hubnerite is not always black. Actually pure hubnerite is reddish-brown or red and is translucent or transparent, but iron impurities can cause it to become black and lessen its translucency until it actually becomes opaque. Other impurities can give rise to other colors in hubnerite such as brownish-black, brownish-yellow, and brown. At one time hubnerite and another mineral called ferberite were thought to be the same mineral (this mineral’s name was wolfram.) Eventually scientists realized that the two were not the same mineral, but just very similar. Ferberite is composed of a chemical called iron tungstate and hubnerite is composed of manganese tungstate.
     Hubnerite is used as an ore of the metal tungsten. Tungsten is used to make steel alloys, the filaments in some incandescent light bulbs, and welding electrodes (the acronym TIG in TIG welding stands for “tungsten inert gas.”) Tungsten is also used to make a chemical called tungsten carbide, which is also known as “hardmetal.” True to its name hardmetal is very hard. I have used a knife sharpener that is made of hardmetal and have personally watched it peel stainless steel like a carrot! Hardmetal is also used to make scratch-resistant rings.
     Hubnerite is found in such places as: Peru, Mexico, Romania, Japan, Bolivia, Sweden, South Dakota, Washington state, North Carolina, New Jersey, and much of the Western U.S. Hubnerite has a place on my list of favorite minerals simply because of its unusual color and the fact that it contains tungsten, which few other minerals do!

An Adventure In Mineral Names (Maybe They do Mean Something Afterall...)

     Let’s be honest, there are a lot of mineral names out there that just don’t make sense. Sometimes it seems like there’s no rhyme or reason to them and that the scientists just wanted to make up the goofiest names possible! Actually the minerals’ names (even the odd ones) do have some meaning behind them. That is what I’d like to explore today.
     Minerals are usually named for something. After all, it is much easier to base a name on something than to simply invent one out of thin air. A lot of minerals are given a name that describes something about them in another language, Latin and Greek being the popular languages to use for this purpose. For example: the mineral scolecite gets its name from the Greek word skolex, which means worm. Scolecite was given this name because it has a tendency to curl like a worm when it’s heated or dehydrated. The second most popular thing to name a mineral after is the proper name of a person or place like ulexite (which is named for the German scientist George L. Ulex) and aragonite (which is named for Aragon, Spain.) Some minerals are named for the elements that make them up like molybdenite and vanadanite, which are named for the elements molybdenum and vanadium respectively, but these sort of names are rare in the mineral world.
     What about the “normal” mineral names? It would appear that most of these minerals were discovered before modern science came about and that the names are simply ancient words for the stones.
     I hope that you’ve had fun learning about the origins of mineral names and I hope that these names don’t seem quite so strange now!

Polymorphism: One Chemical, Multiple Minerals.

     I have a few minerals that I’d like to blog about in the future that are polymorphs, so I figured that it would be a good idea to post a blog about polymorphs first. Polymorphs are simply minerals that have the same chemical makeup, but different crystal structures. For example, the chemical titanium dioxide can actually form three different minerals: brookite, rutile, and anatase. Rutile has prismatic tetragonal crystals, anatase has tabular (flat) tetragonal crystals, and brookite has orthorhombic crystals, yet all three are the same chemical. The chemical makeup of a mineral (its molecules) can determine a great deal concerning the mineral's properties, but the way in which these molecules are arranged when the substance crystalizes can also affect them as well. Think of it this way: if you have three red Lego blocks and four blue ones you can build any number of different objects with them, yet they are the same three reds and four blues. The same thing is happening in polymorphism: one type of molecule might usually arrange itself in one way, giving the crystal certain properties; but it can also arrange itself in another way, giving the mineral a whole new range of properties.
 How does this happen? The way that the chemicals that make up polymorphous minerals crystallize depends a lot on their surroundings. Heat and pressure have a lot to do with what polymorph is formed (by the way, the term “polymorph” also refers to each form of the chemical. For example calcite and aragonite are both polymorphs of calcium carbonate.) There is a great deal more science that could be delved into here, but for now I’ll leave it out.
     Sometimes certain polymorphs of the same chemical are less stable than the other. Anatase and brookite both become rutile when subjected to intense heat, and aragonite will slowly revert to calcite over time and will do so rapidly when heated.
     I hope that the subject of polymorphism in minerals was as interesting to you as it was to me. I also hope to make some posts about a few polymorphous minerals soon!

Crocoite: The...Crocodile Mineral?

     With a name like crocoite it does seem like the mineral must have been named after a carnivorous Egyptian reptile. Actually crocoite’s name comes from the Greek word krokos, which means “saffron.” It was given this name because crocoite has a saffron-colored streak. While crocoite’s streak may be saffron-colored, its crystals are usually reddish-orange in color, but orange, red, and yellowish-orange varieties are also known to exist. Crocoite’s crystals are rectangular prisms that usually grow as long, skinny needles. Crocoite is transparent or translucent and its luster is adamantine (which means that it reflects light like a diamond.) However, it does not serve as a gemstone because it is too soft (not to mention the fact that this adamantine luster can fade when crocoite is exposed to the sunlight. In addition to being soft, crocoite’s crystals are sometimes hollow.
     One of the most historic sources of crocoite is the Australian island of Tasmania where crocoite has been mined for more than 100 years. Other sources include: England, Germany, Russia, France, Austria, Scotland, South Africa, Chile, the Canadian province of Quebec, and the American states of Arizona and California. Crocoite once served as an ore of chromium and was used to make paint. Today it is still used to make a type of specialty paint called “chrome yellow,” but it has been replaced as a chromium ore by a mineral called chromite.
     Crocoite is, in my opinion, a very beautiful mineral. Not only is its color very distinguished crocoite has crystals of an uncommon shape. It’s certainly no ordinary mineral!

Staurolite: An Appropriate Mineral for Good Friday (Part Two)

     Staurolite is certainly interesting as a mineral, but it can represent something far more important. Staurolite can serve as a reminder of what our Savior endured on our behalf. If you already know the Savior now would be a good time to thank Him for suffering death on a cross for you. If you do not know the Savior there is no better time than now to do so. No human is perfect and God requires that only those who are perfect may go to Heaven when thy die. However, Jesus, God’s one and only Son, died to pay the penalty of sin, even though He had never sinned. Now absolutely anyone can be made perfect by the power of Jesus. All you have to do is ask Him to forgive your sins and come into your heart. You can say something like this to him: “Dear God, I know that I am a sinner and deserve to be punished. I believe that Jesus is your Son and that He can heal me. I am ready to turn away from my sins and I believe that Jesus is your son. I ask him to come into my heart. Thank you, Jesus, for coming into my heart like you promised. Amen.” If you have prayed that prayer and meant it than your sins are forgiven past, present, and future and you are now part of God’s family. You will go to Heaven when you die and you have God’s Holy Spirit living inside of you at this very moment and He will never leave. That is a greater treasure than all of the minerals in the world!

Staurolite: An Appropriate Mineral for Good Friday (Part One)

     Staurolite crystals are hexagonal prisms that can be reddish-brown, yellow-brown, brown-black, or rarely blue in color. It is not altogether uncommon to find staurolite crystals on a matrix. In the mineralogical world the term matrix refers to a piece of rock or dirt that a crystal is connected to. Staurolite crystals are famous for their twinning properties as well. Staurolite crystals have been known to intersect each other at angles of 60 and even 90 degrees, thereby forming cross-shaped crystal twins. This is actually where staurolite gets its name from. The name “staurolite” is composed of the Greek words stauros (which means “cross”) and lithos (which means “stone”) so staurolite’s name actually means “cross stone.” In addition to its scientific name, staurolite twins are known by a number of nicknames, the most famous of which is “fairy cross.” Other nicknames include: “cross stone” “faith cross” and “angel cross.” appropriate
     Staurolite has been used as a cross symbol since Medieval times. In those days staurolite twins were collected and used to represent Christ’s cross both on a matrix and free of one. Those that were free of a matrix were used to make pendants. Today staurolite crosses are used to make pendants and broaches, and small ones are used to make earrings. Finely ground staurolite can also be used as an abrasive in sand-blasters when a medium that is harder than quartz is required. Blue staurolite can also be used to make pigments.
     Staurolite is found all over the world, but collectible specimens are found in only a few places. Such places include: Russia, Ukraine, Japan, China, Spain, Turkey, and the Appalachian Mountains of North America.

Sharing Your Collection With Others: One of the Best Uses For a Rock Collection

     Yesterday I had the opportunity to share my rock collection with others. I always love to show the minerals I’ve collected to other people and hopefully foster an interest concerning the subject in some of them.
     I brought my collection to a home schooling co-op and talked about it as well as some interesting facts about minerals like: the sources of a mineral’s color, the meanings behind mineral names, and much more. I also shared a few tips about mineral identification like the streak test and the Mohs’ scale. After my little talk ended everyone simply looked at my collection a bit and I answered a few questions. Then it was my turn to have a look at their collections and I must say that the students had some pretty nice specimens! I did my best to identify some of the minerals that they found and for the most part I could tell what sort of minerals they had, but there were some samples that I simply could not identify. Everything must have gone well because I had one student thank me for coming three times! What an honor!
     To all of the collectors out there I say that if you ever get a chance to show your minerals to other people you should do it. It provides a chance to get other people interested in the hobby and best of all it can offer us an opportunity to thank the Lord for blessing us with our fine minerals by using them to bless others!

Iolite, Now There's a Mineral of a Different Color!

     I think that it’s safe to say that iolite could be the face of pleochroic minerals. Pleochroic minerals are minerals that exhibit different colors when viewed from different angles. Iolite appears to be violet-blue when viewed down the length of its crystals, but colorless when looked at from the side of its crystals. This amazing change of color makes iolite one of my favorite minerals. Unfortunately my piece doesn’t display this pleochroism. Perhaps the fact that it’s too compact to allow a lot of light to pass through it has something to do with that.
     Iolite is said to have orthorhombic crystals, but I’ve never seen a picture-perfect iolite crystal, so I can’t describe what it looks like except for the fact that it’s prismatic and has flat faces. Iolite is also found as compact masses. I have seen transparent and translucent iolite, but I’m not sure if it can be opaque. Iolite has a vitreous luster like quartz and shares quartz’s Mohs scale hardness of 7. Because it is dichroic (dichroic means that it is pleochroic with two different colors) iolite is also called dichroite. Iolite is also known by the names cordierite and ‘water sapphire.’ Iolite’s only commercial use outside of collecting is as a gemstone.
     You can find iolite in places like: India, Myanmar, Sri Lanka, Madagascar, Norway, Finland, Germany, and Wyoming.
     Iolite is one of my favorite minerals simply because it has some of the most remarkable pleochroism that I’ve ever seen. It’s a really cool mineral and I’m glad that God saw it fit for me to have a sample of it!

Native Elements: Building Blocks in Pure Form

     Native elements are rare among minerals. Of the 4,600 or so different mineral types out there only about twenty of them are native elements. What is a native element? A "native element" is simply a chemical element (a member of the periodic table) that can be found uncombined in nature. The elements on the periodic table usually link up with other elements to form compounds and to get samples of these elements people usually have to separate them from their compounds (this is actually what is happening when people extract metals from their ores.) However, some elements can be found not combined with any others. These are called “native elements” and they are considered to be minerals.
     The elements gold, silver, copper, lead, platinum, palladium, iridium, osmium, iron, mercury, tantalum, tin, antimony, arsenic, bismuth, selenium, tellurium, carbon, and sulfur have all been found as native elements. They have crystal structures like other minerals, but I don’t plan to discuss their appearance. Some of these elements can also be found as native alloys (an alloy is a mixture of metal.) Native iron, for example, quite often contains nickel. The elements osmium and iridium are never found pure in nature, but always as natural alloys. Native iron is seldom found on earth; it’s usually found in meteorites. People in at least three countries have reported finding native zinc, but no one has proven it yet.
     Native elements are rare among minerals. In my opinion they are some of the most interesting minerals on earth. For this reason I am glad that God saw it fit to leave some of His building blocks in pure form for people to find!

Sodalite...The Soft-Drink Mineral?

     With a name like sodalite one might think that this is a mineral fit for drinking. Actually, sodalite is named for its sodium content.
     Sodalite is a mineral that rarely forms crystals. Dodecahedral (twelve-sided) crystals of sodalite have been found in the lava of Mt. Vesuvius, but sodalite is generally found in massive form. Pure sodalite is transparent or translucent and colorless, but the mineral is most often found as opaque masses that come in all shades of blue. Sodalite is a component in the rock lapis lazuli. You can tell lapis lazuli and sodalite apart by the fact that sodalite has a lower specific gravity (feels lighter when you hold it in your hand) and does not usually contain pyrite as lapis lazuli often does. Sodalite can, however, contain streaks of the mineral calcite (I think that the white streaks in the picture are examples of these.)
Sodalite’s main use is as a decorative stone. Sodalite is often cut into cameos, cabochons, and tumbled in rock tumblers.
     A major source of sodalite is Bancroft in Ontario, Canada. Sodalite was discovered there during a visit from Princess Margaret of England, so sodalite from Bancroft is sometimes called “Princess Blue.” other sources include Brazil, the USA, Namibia, and India.
     Sodalite can be a nice addition to one’s mineral collection. Just remember: it’s not for drinking!

Native Copper: the Mineral that You Can't Confuse With any Others

     Copper is a metal on the Periodic Table of the Elements. Elements are considered minerals when they are found in pure form in nature. In such cases they are called “native elements.” Copper that is found in this manner is called “native copper.”
     Native copper is usually found as twelve-sided crystals (which are called dodecahedrons), but they can also form as eight-sided octahedrons, six-sided cubes, and twenty-four-sided tetrahexahedrons. A lot of the time these crystals grow in clusters, in a dendritic habit (which looks like the branches of a tree) as wires, or in the form of nuggets. Since copper is very soft its crystals can be distorted and squished. Native copper has been known to from as a coating on other rocks and if the rocks dissolve away the copper sometimes remains as a mold of the original rock. When these rocks are round the leftover copper is called “skull” copper. Native copper has also been found as inclusions in other minerals such as agates. Because of its bright "coppery" color, native copper cannot be confused with any other mineral.
     Until the twentieth century native copper served as the world’s main source of the metal. Today native copper is still used for this purpose, but most copper comes from ore stones now. People have used copper to make jewelry since ancient times and still use it to make things like broaches, rings, earrings, and bracelets today. Copper is very important in industry; in fact iron and aluminum are the only metals that are more widely used than copper! Copper is used to make electrical wire as well as plumbing pipes and is also used to make alloys such as brass and bronze. Copper is also used to make coins in many countries including the United States.
     One of the most famous sources of native copper is Michigan’s Upper Peninsula where it has been collected for about 4,000 years. Other sources include: Cyprus, Kazakhstan, Norway, Cuba, China, Zaire, Canada’s Yukon Territory, and the American states of Alabama, Arizona, Connecticut, Missouri, and Utah.
      Native copper belongs to a rare category of minerals. Of the 4,400 or so different minerals out there only about 20 of them are native elements. That much being said I’m sure glad to have some native copper in my collection!

The Gem and Mineral Show: A Great Way to Spend an Afternoon

     This last Friday I went to a gem and mineral show hosted by the Michigan Gem and Mineral Society of Jackson at the Jackson County Fairgrounds. The society hosts these shows to help foster an interest in rocks and minerals in people who don’t know a lot about them, especially young people. This was the 49^th annual show hosted by the society.
     At gem and mineral shows there are usually dealers there selling fine specimens of rocks and minerals and at this one there were more than twenty dealers present. I would venture to say that at least one third of them sold minerals that had already been cut and polished, which I wasn’t too interested in, but the others sold rocks and minerals in their natural, uncut state. I came bearing a list of minerals that I wanted to buy: meerschaum, cassiterite, iolite, fire agate, cerussite, and a nodule of manganese metal. I found only the iolite and the fire agate (and of the two I bought only the iolite) but I also purchased a piece of mimetite. After asking about the meerschaum (which I’ve been looking for for a few years) and the cassiterite I learned that I have some rare and expensive tastes when it comes to minerals! There were a lot of other interesting minerals there too, a lot of which I would like to own, but I didn’t want to spend all of my money on them!
In addition to the minerals it was advertised that there were rock and mineral activities, but I did not participate in any of them and was to focused on the minerals to notice anything else.
     I had a lot of fun at the show and would recommend them to anyone who is interested in rocks and minerals. P.S. keep your eyes open for future posts about mimetite and iolite!

Gypsum, the Mineral About the House

     Gypsum is a very soft mineral. It only measures a 2 on the Mohs scale of hardness so you could easily scratch it with your fingernail! Gypsum is an evaporate mineral, it is usually white, yellowish white, or colorless; and its transparency ranges from transparent to opaque. Transparent crystals of gypsum are called selenite. Gypsum crystals belong to the monoclinic crystal group and look like flat parallelogram-shaped prisms. Gypsum can also have needle-like crystals and fibrous crystals. Fibrous gypsum crystals are sometimes called satin spar. Gypsum’s needle-like crystals are sometimes found growing in a radiating pattern. They kind of look like flowers and are called “daisy gypsum.” Gypsum crystals often twin to form arrowhead-shaped twins called “fishtails” or swallowtails.” Gypsum sometimes forms what is called a “desert rose,” which you can see at the bottom of the picture.
     When gypsum is heated it looses a lot of the water that makes up part of its chemical structure. If you add more water to this dehydrated mass it will become gypsum once again and will harden into a solid piece. This is how plaster of Paris is made. Gypsum is also used to make a type of wall board (sometimes called “gypsum board”) that is used in drywall construction. If you live in a house that is made with these kinds of walls then you are surrounded by a lot of gypsum!
     Gypsum is found in many places throughout the world. Some hard water deposits are gypsum so every time you have to scrub that white stuff off of your shower head it’s possible that you might be scrubbing away gypsum! A lot of gypsum (enough to be mined) can be found in these places: Great Britain, Canada, Italy, and these U.S. states: Michigan, New York, Ohio, Iowa, and Texas. France is another source of gypsum. Plaster of Paris was actually named for the Paris basin where gypsum can be found.
     Gypsum is a fairly useful mineral, it’s quite soft, and its crystals can make some pretty interesting formations. All of these facts are cool, but I think that the most captivating one is that I am surrounded by gypsum every day!

Epidote, it's Picture Perfect

     Epidote’s crystals are near perfect examples of the diagrams of monoclinic crystals that I have seen in rock & mineral books. They look like gemstones that have been given a rectangular table cut or two pyramids that have been fused at the base and have had their caps cut off. Their flat faces are rectangular and not square and that is why I have called them near perfect examples of monoclinic crystal diagrams. These crystals are usually tabular or long, skinny prisms. Epidote’s crystals are often acicular (needle-shaped) or radial (they radiate from a central point like the spokes of a wheel.) Epidote is usually yellow-green in color, but can also be pistachio green, brown-black, or green-black and less commonly: pink, yellow, black, and gray. Epidote has a vitreous luster (it reflects light like quartz and glass do) but its cleaved surfaces have a pearly luster (a luster that resembles that of a pearl or mother of pearl.) Epidote can be transparent, translucent, and sometimes opaque. I have read that epidote is pleochroic (it changes color when looked at from different angles) but I haven’t seen any pleochroism in my specimen yet.
     Epidote and pink feldspar sometimes grow together to form a rock called unakite. Unakite is used to make jewelry and carvings. Epidote is used for those two purposes as well, but unakite is more popular.
     Epidote is found in many different places. I know of almost thirty different locales in which epidote is found, but have decided to mention only a few to keep this post short: Bolivia, Peru, Brazil, Norway, France, Kenya, South Africa, Mozambique, Mali, Montana, Maryland, Arkansas, Virginia, Japan, and Azerbaijan.
     Epidote has very simple crystals that can grow in interesting ways and it is an ingredient in a rock that people like to use for decoration. By now you might want to be adding epidote to your collection and with all of the places where it can be found you might just be able to find some where you live!

Spinel: Ruby, Version 2.0

     Make no mistake, spinel is its own mineral with its own chemical makeup, and not a variety of ruby. Why then did I call it ruby, version 2.0? Read on and discover what I learned about spinel and why I labeled it like I did.
     Red spinel is very similar to rubies and was once thought to be a type of ruby. Spinel was once called “balas ruby” and orange-red or orange-yellow spinel is called rubicelle (red spinel is sometimes called “ruby spinel.”) Spinel sometimes displays asterism, a phenomenon that causes a star shape to appear in the cabochons of some minerals; rubies can also display asterism. All of this reasserts the point that spinel can be a lot like a ruby; almost like a ruby version 2.0.
     Spinel crystals are octahedral, which means that they have eight faces. Spinel crystals look like two pyramids that have been connected at the base. Spinel can be red, blue, purple, orange-red, pink, or orange-yellow. In some spinels the color is so faint that the stones can appear colorless at a first glance. Spinel can be transparent, translucent, and nearly opaque and it sits between quartz and corundum on the Mohs scale of hardness, making it as hard as topaz. In addition to the asterism described above spinel can also have brown zircon inclusions that are surrounded by brown halos. Spinel is sometimes a component in a rock called emery.
     Spinel is used as a gemstone because it is quite pretty and the fact that it is so similar to rubies probably doesn't hurt. Emery is used as an abrasive, and to make items such as fingernail files (which are sometimes called emery boards) and sandpaper. In the United States spinel is sometimes added to pavement to help improve traction.
     Spinel is found in places like Sri Lanka, Vietnam, Myanmar, Madagascar, Afghanistan, Sweden, and Turkey.
     I am of the opinion that God created everything for a purpose. Spinel can certainly serve its purpose as a gemstone, but perhaps it also serves another. Perhaps the Lord was so pleased with His creation of the ruby that He created spinel as another version of it for us to enjoy!

Moonstone, a Mineral of the Moon?

     Moonstone’s name might suggest that it's of a lunar origin, but moonstone is from the earth. Moonstone is actually a type of feldspar that is named for its sheen, which reminds some people of the moonlight.
     Moonstone is a variety of feldspar that is named for its adularescence. Adularescence is the term for the type of sheen that moonstone exhibits, which resembles moonlight. Moonstone is orthoclase feldspar with alternating layers of albite feldspar in it. The way in which these layers reflect the sunlight is what gives moonstone its sheen. The sheen can be either blue or white depending on the layers inside of the moonstone. If the layers of albite are thin then the moonstone’s sheen is blue. If they are thick then the sheen is white. Moonstone itself is usually colorless, white, or a light shade of blue-gray, but it can also be orange, blue, yellow, brown, or green. Moonstone’s crystals are monoclinic, but I have personally never seen whole moonstone crystals (all of my samples appear to be broken pieces) so I can't describe their appearance. Moonstone’s transparency ranges from almost transparent to almost opaque.
      Moonstone serves some use as a gemstone because its moonlike sheen is very desirable. The best moonstone comes from Sri Lanka and Myanmar. Other sources include: India, Madagascar, Tanzania, Brazil, Mexico, the United States, and the European Alps.
     Moonstone possesses some rare qualities among minerals. Its moonlike sheen is, as far as I know, unique to moonstone. Moonstone may be a lot of things, but just remember, it’s not from the Moon!

The Rainbow of Topaz

     Topaz is a gemstone that has been known about since ancient times. The mineral was named for the Mediterranean island of Topasos (which is now called the island of Zebriget.) Interestingly that island was never a source of topaz.
     Topaz crystals are orthorhombic. They are prismatic and their shape is difficult to describe. The crystal is composed of two large faces on both sides of the prism that meet like a peaked roof at the middle of the crystal. These faces give way to another face that looks like the Superman symbol at the top and bottom of the roofs on both sides of the crystal. At the top corners of these strange pentagons there are two regular pentagons that meet with two others on the other side. Atop the two Superman symbols and four pentagons there is one elongated pentagonal face that makes the apex of the crystal. The two peaked-roof shapes would meet with the two others on the opposite side to form a diamond-shaped cross-section, but they are separated by two other faces that connect to make two other peaked shapes. Like I said, topaz crystals are a little difficult to describe!
     In addition to having interestingly-shaped, prismatic crystals topaz also has a lot of interesting optical properties. Topaz is transparent and can be white, colorless, golden-yellow, green, brown, yellow, red, pink, orange, red-orange, and rarely violet and blue. Topaz often fluoresces (it glows under ultraviolet light, aka black light) and topaz’s color can be changed by heating it. Yellow topaz is often heated to change it to a more desirable pink color. Clear topaz can be turned blue by radiation. However, these synthetically-colored stones cost less than specimens that were colored naturally. Topaz can also fade in direct sunlight if exposed for prolonged periods of time, so for anyone who has a sample of the gemstone I would recommend that they store it out of the sunlight. I also wouldn't try the black-light test on it until first talking to an expert. 
     Topaz is used as a gemstone. It is the birthstone for the month of November and the traditional stone of 16^th wedding anniversaries. Topaz is also ground and used as an abrasive. It is a hard stone, harder than quartz, but it is brittle and can chip so great care must be taken when cutting it. Sometimes other gems are given names that make them sound as if they are a kind of topaz. For example citrine (a yellow-colored variety of quartz) is sometimes called “golden topaz” or “citrine topaz.” Real topaz is often called “precious topaz” to help to distinguish it from the other gems with the misleading names.
     Topaz is found in many places, but the best specimens come from places like: Finland, Sri Lanka, Myanmar, Wyoming, Utah, Maine, and Connecticut. Most of the world’s topaz comes from Brazil.
     Topaz is one of the better-known minerals that I’ve written about. Once you take into account all of its amazing optical properties it makes sense that many people have heard of it!

Hematite, it's Pretty Spectacular!

     Hematite is an iron oxide mineral that is used as an iron ore. Hematite is often red or reddish brown in color, but it can also be silvery-gray or black with a metallic luster. All hematite is opaque (it does not allow light to pass through it) Hematite crystals are hexagonal (six-sided) and flat. Hematite is also found as massive pieces (in mineral terms the term “massive” refers to a shapeless mass that is made of many tiny crystals), earthy chunks, and reniform masses. The word reniform means kidney-shaped. Reniform hematite is often called “kidney ore.” Shiny hematite is known as “specular hematite.” Hematite can also be iridescent, that is to say that light makes a rainbow-colored pattern when reflecting off of its surface. Hematite crystals are also known to grow in rose-shaped clusters, which are called “iron rose.” Hematite is similar to the mineral magnetite, but it is different in the fact that while magnetite is magnetic, hematite is not.
     In my post about pyrite I talked about the streak test, which is used to help identify minerals. The streak test is preformed either by scraping a mineral across a piece of unglazed white porcelain or grinding that mineral into powder. This test is useful because two different minerals may have the same crystal shape and color, but different-colored streaks. Some minerals, like hematite, may exhibit more than one color, but their streak always remains the same. Hematite is an example of such a mineral because whether red or silver hematite always leaves a red streak.
     Hematite is one of the most useful minerals that I know of. Hematite is the main iron ore used in industry today, and there are a great many things that are made from iron. The primary use of iron in today’s society is as a component in steel. Specular hematite was once used to make mirrors and it is still used to make some kinds of jewelry today. Synthetic hematite can be made by heating and compressing small pieces of the mineral until they become a solid piece. Interestingly, synthetic hematite is magnetic and has a gray streak. Ground hematite can be used to make a kind of reddish-brown paint, an abrasive, and a polishing powder called “jeweler’s rogue.”
     Hematite deposits in Michigan and Minnesota were once the world’s richest source of the mineral. I have actually toured a hematite mine in northern Michigan and learned that the hematite works like a thermos underground and keeps the place at 40degrese F constantly, even during the springtime when I went! The deposits in Michigan and Minnesota have been mined a great deal and no longer serve as the world’s richest source of hematite, but there is still some left there. Other sources include: England, China, Switzerland, Brazil, Pakistan, Australia, Wisconsin, Alabama, and New Hampshire.
     Hematite is, like many minerals, useful in industry, stunning as a gemstone, and beautiful as a natural specimen. It is pretty spectacular!

Celestine, a Naturally-Faceted Gem

     Some of my favorite minerals to write about are the ones that I have found while rock hunting. On a rock-hunting trip (rockhounds call these “field-trips”) I found a mass of blue crystals. At first I thought that I had simply found a sample of calcite, but after I conducted a little more research I learned that they were probably crystals of a mineral known as celestine.
     Celestine is a mineral that is composed of the elements strontium, sulfur, and oxygen. The mineral is often found in limestone, evaporate deposits, or with other minerals such as galena and sphalerite. Celestine is transparent and is usually colorless, milky white, brown, pale blue, or yellow. The appearance of celestine’s crystals are difficult to describe simply because of their marvelous shape. They are flat prisms that look as if they have already been faceted as gemstones. The prisms have two faces that meet in a peak like the blade of a broadsword, and two like faces on the sides. These prisms look like chisels on the ends. Like I said, they are a little hard to describe.
     Celestine is used as a source of the metal strontium, the compounds of which are used in the refining process of sugar beets and for making devices such as flares, as some strontium compounds burn with a crimson red flame. Celestine is not used as a gemstone because it is very soft and will scratch during everyday ware, but if it was hard enough to use as a gemstone its crystals are so beautiful in their own right that we might not even have to cut them!
     The specimen that I found came from a rock-hunting park near Toledo, Ohio. Other sources of celestine include: England, Italy, Madagascar, Namibia, Canada, Turkmenistan, and California.
     Celestine is one of the best finds that I have made on a rock hunt. Once I brought my sample home it was a challenge to identify it, but as a result my mineral-identification skills have improved. I am thankful that the Lord allowed me to find celestine, a naturally-faceted gem.

Geodes, Crystals Living in Their Own Little Worlds

     For as long as I have known about them, geodes have always captivated me. Sometimes a geode may contain hundreds of little shimmering crystals that might never have seen the light of day until you broke open their rocky confinement. My dad once said that crystals inside of a rock, like a geode, are like their own little world. Interestingly, the word geode comes from the Greek word geodes, which means “earthlike.”
     What are geodes? A geode is simply a hollow rock that is filled with crystals. Think of a basketball that has been inflated and filled with salt water. After a while the salt crystallizes on the inside of the basketball, thereby forming a lining on the sphere's interior. This is the way that geodes are formed, only the lining takes place inside of a hollow rock and with different crystals. Some of the most common minerals that make up the interior of geodes are: quartz, pyrite, calcite, barite, gypsum, strontianite, and a group of minerals called “zeolites.” Geodes are famous for being spherical (ball-shaped) but they can be stretched spheres or even shapeless. Geodes can be very tiny, golf-ball sized, baseball sized, basket ball sized, or even larger. Tiny geodes are called ocos. Some nicknames for geodes include: “eagle stones,” “thunder eggs,” and “echites.”
     According to science, geodes can be formed in two different ways; one by sedimentary activity and the other by volcanic activity. Volcanic geodes are thought to form when lava erupts from a volcano and a large bubble of gas is trapped inside of it (in mineral terms a gas bubble that is trapped inside of a rock is called a vesicle). This vesicle is then filled with mineral-rich water, which the crystals grow from. Geodes made by sedimentary activity are formed when natural acids dissolve a cavity into a rock. The crystals are then formed in this cavity by the action of mineral-rich water just like the volcanic geodes. Volcanic geodes are usually more spherical in shape and most often contain quartz and zeolites whereas the geodes formed by sedimentary activity are usually oddly-shaped and contain the other minerals listed above.
     Geodes do not serve many technological uses. If any of the minerals found inside of them do, I would assume that it is more cost effective to get them from sources other than geodes. Geodes are sometimes sliced into very thin sheets, which are used in jewelry making. Geodes are used mainly as decorative pieces and many mineral collectors like to collect them.    
     Geodes are found in many places throughout the world (in fact, I once found one on my grandmother’s property here in Michigan.) Some of the best geodes come from places like: Western Sahara, Morocco, Germany, Oregon, and Kentucky. Very large geodes can be found in Iowa, Missouri, and Illinois, and  geodes both large and small that are filled with purple amethyst crystals can be found in Brazil and Uruguay.
     Geodes interest me for a number of reasons. The beautiful crystals inside of them, their semi-complex origin, and the interesting shape that geodes often assume make them simply stunning. Geodes can remind me of miniture caves filled with glittering crystals. And sometimes they do seem like their own little worlds!

Jet Black

     Jet is a variety of lignite, a form of coal (you can read more about lignite and coal in December 24, 2010's post.) Jet shares some properties with lignite, but the two rocks do differ somewhat. Jet and lignite are alike in the fact that both are either black or brown and have an amorphous structure. They differ in the fact that while most other lignite is soft, crumbly, and dull, jet is hard and has a shiny surface. Jet has been found bearing pyrite inclusions and sometimes it even contains fossils. Jet is a very light rock and when rubbed it can produce static electricity like amber. For this reason jet is sometimes called “black amber.” Jet smells like burning coal when burned or touched with a hot piece of metal.
     Because of jet’s light weight and ability to polish well it has been used to make jewelry since ancient times. Carved jet was once shipped from what is now England to the ancient Rome, and because of jet’s black color it was a popular stone for mourning jewelry during the 1800s. Today jet is used to make costume jewelry and buttons.
     The most historic source of jet is the region of Yorkshire, England, specifically the town of Whitby. Other sources include: Poland, Turkey, France, India, China, Germany, Spain, and the USA.
     Jet has remained on my list of favorite rocks for a long time and I am glad that God saw it fit to create it.

Azurite: the Blueberry Mineral

     Azurite is an azure blue mineral that is named for its color. Azurite is idiochromatic, that is, its color comes from its own chemical makeup and not from impurities. Perfect azurite crystals look like sword blades, but these are not quite so common and azurite is more often found in other forms like stalactites and stalagmites, crusts on top of other rocks, and sometimes botryoidal aggregations. As many of you may know the term “botryoidal” refers to a way in which crystals grow that looks like a bunch of grapes. However, I personally think that botryoidal azurite looks more like blueberries than grapes. When cut open azurite can resemble malachite, looking somewhat like a blue agate.
     Azurite and malachite are very similar. They are often found growing together and are even mentioned together in some books. This is because the two minerals have a very similar chemical makeup. Both are composed of the same kinds of atoms; they simply differ in the number of those atoms that make them up. Azurite can actually turn into malachite when it is exposed to the air or to water for extended periods of time. I have read that, like malachite, azurite can form on the surface of metallic copper, but I cannot personally vouch for this because I have never seen it happen myself. Because they are so similar azurite is sometimes called “blue malachite.” When azurite and malachite grow together they are sometimes collectively called “azurmalachite.”
     Azurite was once a prominent copper ore and is still used for this purpose today, though less extensively. Possibly the greatest use that azurite has ever served is as a paint-making material. In Europe, during the Renaissance, azurite was used as a blue pigment quite extensively, but that use came to a screeching halt during the 1600s. The reason that people stopped using azurite to make paint is because of the fact that it can turn into malachite and thereby change from being blue to being green. After a while people began to notice that the deep blue skies in some of the older paintings began to turn green! Soon after this they began to make paint out of other substances that would hold their color. Today azurite is used as a decorative stone, mainly in the area of carving, though it does serve a tiny use in jewelry. Azurite is also very popular with rock and mineral collectors. In fact, some rockhounds say that no collection is complete without azurite!
     Azurite can be found wherever copper deposits are present. Some of the best specimens can be found in such places as: China, France, Zambia, Australia, Namibia, Bolivia, Pennsylvania, Arizona, Nevada, New Mexico, New Jersey, and Michigan.
     Azurite is a common mineral, but the intensity of its deep blue color seems to render that fact unimportant to mineral collectors. After reading this post you might be able to see why azurite is such a popular mineral to collect!

Ions--God's Mineral Dye (Expirement #1)

     For a while I have wanted to do some rock and mineral-related experiments and write about them. I thought about the idea for a while, and thought about it, and thought about it… …Well now I’ve done one and the time has come to share the experiment with all of this blog’s readers.
     I first received the idea to do this experiment when I was reading about the mineral chrysoprase. I learned that chrysoprase is actually turned green by nickel ions that are present in it. I remember from chemistry class that an ion is an atom that has gained or lost an electron. Without an intense in-depth discussion on the science involved here I will say that some compounds are divided into the ions that make them up when they are dissolved. Now, a friend of mine and I have both done some experiments with citric acid and I have learned that a high concentration of the stuff can dissolve the copper-nickel coating off of a coin such as a dime or quarter. With this knowledge I knew that the solution (which had turned green) probably contained some copper and nickel ions. I then set to work to try to figure out whether or not I could grow crystals in a solution of nickel ions and see the crystals appear green.
     I started my experiment by dissolving a hearty amount of citric acid granules in water, continually adding more citric acid until the solution became saturated. I then dropped in two American nickels from the 1960s (those from that era have more nickel content in them than today’s do) and allowed this to sit for a while. After a few weeks or so the solution began to get a greenish tinge about it. I could have introduced something like salt to the mix to try to get some crystals growing at that point, but I wanted to see if the solution would become any greener.
     To make a long story short I will say that I let the solution sit for too long and the citric acid re-crystallized before I could try to grow anything else in the solution. However, the citric acid crystals, which are usually white or colorless, do appear to be green! Success! My first experiment with God’s mineral-dye has worked, now all that I might have to do is dissolve those crystals into some water and attempt to grow some other kind of crystals in it.

Orpiment--The Deadly Paint-Maker

     Orpiment is arguably one of the most toxic minerals that I have in my collection. The reason that orpiment is so dangerous is because it contains the element arsenic in its chemical makeup, and arsenic is one of the most toxic of all of the chemical elements. Most compounds that contain arsenic are toxic. Despite this, both arsenic and orpiment are used in today’s industry in small amounts.
     Orpiment is either yellow or orange. Orpiment crystals belong to the monoclinic crystal system, which I have written about in former posts. Orpiment is more often found in tight-packed clusters, some of which resemble a yellow dandelion’s head. Orpiment can often be found as a hot spring’s deposit, which means that the crystals grow from the mineral-rich waters of some hot springs.
     Orpiment is famous for its golden color. In fact, during the Middle Ages there were some alchemists who tried to extract gold from the mineral! Ancient artists in the Middle East used orpiment to make gold-colored paint for a long time, and European artists eventually began to do the same. This use lasted for a while, but is not quite as prominent today. Once people discovered that orpiment was toxic they only used it to make a very special paint called “king’s yellow.” Today king’s yellow is made with a different compound for the most part, but you can still buy it (I know this because I found a website that sold orpiment king’s yellow while researching the mineral.) In addition to its use as a paint-maker orpiment is also used as an ore of arsenic, which is used in metallurgy.
     Orpiment is found in such places as Romania, Japan, Peru, Russia, the country of Georgia, Utah, and Nevada. Since orpiment can be found as a hot springs deposit it is also found in some of the hot springs in Yellowstone National Park.
     I have certainly had fun learning about orpiment, and I would like to thank anyone reading this for letting me share my new knowledge with them. A word of warning, though: use caution when handling orpiment--always wash your hands after handling it!

Smithsonite, Where Did That Name Come From?

     Does the name of this mineral sound familiar? Smithsonite and the Smithsonian Institute have very similar names and that is because they were both named for the same person: James Smithson. This happened because the man who donated his estate to what is now the Smithsonian also discovered that the mineral calamine was actually two different minerals: smithsonite and zinc oxide.
     Smithsonite crystals are rhombohedra (that means that they have six diamond-shaped faces). Smithsonite in crystalline form is rare, however, and the mineral is more often found as banded stalactites or in botryoidal form. Like many minerals smithsonite is white or colorless when pure, but impurities can cause it to appear to have different colors. In smithsonite the most common colors are: green, purple, blue, brown, yellow, gray, or pink. Smithsonite is translucent (it allows light to shine through it) and is affected by mild acids.
     Smithsonite contains zinc and was used as a zinc ore until the 1800s. The ancient Romans made brass (an alloy or mixture of copper and zinc) by smelting copper ores and smithsonite together. They did not know that smithsonite contained zinc or even that adding zinc to copper made brass, they just knew that they would get brass by smelting those two rocks together. The metal zinc was not discovered until the mid 1700s when a German chemist by the name of Andreas Sigismund Marggraaf discovered it in, you guessed it, smithsonite. Today smithsonite has few uses outside of collecting as it is a little too soft to use in jewelry and better zinc ores have been found. Smithsonite does serve a limited use as a decorative stone and it can be ground to make fertilizer for agriculture.
     Smithsonite is found in such places as: Italy, Poland, Australia, Brazil, Bolivia, Japan, Zambia, Argentina, Greece, and Morocco.

Vanadinite, Please, Sir, May I 'Ave Some Ore?

     Vanadinite is one of my favorite minerals, and it brings me great pleasure to write about it today. Hopefully after reading this, vanadinite will be one of your favorite minerals as well.
     Vanadinite crystals are very simple, but they are still quite stunning. They are hexagonal prisms like quartz, but they don’t have the pointy ends that quartz crystals do. If you will, they are like six-sided cylinders. Vanadinite is of a bright orange-red color and can be translucent or transparent. Vanadinite is very shiny, so shiny that it will sparkle when turned about in the sunlight. Vanadinite’s luster (the rock and mineral-world term for the way a mineral reflects sunlight) is described as adamantine. That means that its luster can be compared to that of a diamond!
     Vanadinite has served as an ore of two different metals: lead and vanadium. Lead once had a lot of uses, but today, since we have discovered that it is poisonous, it serves far fewer (read more about the uses of lead in my Dec. 16, 2010 post Galena, Beautifal, but Dangerous) Vanadium is used primarily to strengthen steel by alloying (mixing metals.) Vanadium is added to steel to make it stronger and less likely to rust. Vanadium steels are used to make such things as car parts, tools, and knives. And, as I have suspected for a long time, vanadinite is named for vanadium.
     Vanadinite is found in such places as: Arizona, Nevada, New Mexico, Mexico, Scotland, Austria, Zambia, and Morocco. One other very specific source is Custer County, South Dakota. I have done some rock collecting in Custer County, but I did not find any vanadinite while doing so.
     Vanadinite has a lot of traits that I find most desirable in a mineral. It is rare, it is beautiful, it contains lesser-known elements in its chemical makeup, and it has some technological uses. No wonder vanadinite is one of my favorites!

Fluorapophyllite--That's an Odd Name!

     Fluorapophyllite certainly does have a strange name. Believe it or not its name is actually quite new. Fluorapophyllite belongs to a group of minerals that were all once thought to be one mineral, which was called apophyllite. When scientists realized that these minerals slightly differed because of their chemical makeup they renamed the individual minerals and the name "apophyllite" was given to the mineral group. The individual apophyllite minerals were renamed by combining the name apophyllite with the name of the chemical component that is unique to the individual mineral. For example, the apophyllite mineral that was rich in fluorine was renamed fluorapophyllite. The name apophyllite is composed of the Greek words apo, meaning “off” or “detached” and phyllon, meaning “leaf.” It was given this name because of its tendency to flake apart when heated.
     Fluorapophyllite has a very complex crystal structure. One form of fluorapophyllite crystal looks like a six-sided die that has had all of its faces’ corners cut off. The other looks like an octahedral prism (that is, it looks like two pyramids connected at the base.) The caps of these pyramids are intact, but all other corners are cut off. Fluorapophyllite is either translucent or transparent and is usually white or colorless. It can also be pale green, gray, yellow, or red. When broken or cut, fluorapophyllite can reflect sun in such a way as to have a grayish blue, pearly luster; so it is sometimes called “fish-eye stone.”
     Fluorapophyllite has no technological uses and has only limited use in jewelry. The only real use that people have discovered for the mineral is as a nice addition to rock and mineral collections.
     Fluorapophyllite is an unusual mineral, but in my opinion “unusual” can be just another word for “intriguing.” Fluorapophyllite is certainly intriguing…now if we could just come up with name for it that’s easier to spell!

Malachite: the Beautifal Rust

     Malachite is a green mineral that is formed by the chemical weathering of copper; basically it is copper rust. If you have ever watched a piece of copper turn orange, then brown, and then green you have witnessed the formation of the mineral malachite. The malachite that people find in the ground is formed the same way and often grows on top of natural copper deposits. This malachite often forms in layers and can eventually become quite thick. When malachite of this nature is cut open a certain way it looks like a green agate with bands that alternate between light and dark green. The layers of malachite may be of varying hues, but its color does not alter: all malachite is green. In addition to forming as a rust on copper, malachite can also be found as nodules, botryoidal aggregations, and stalactites, as well as monoclinic crystals. A lot of monoclinic crystals that I have seen look like two keys from a keyboard that are fused at the base so that the face that has the letter on it is visible on both keys. I have never seen malachite with individual monoclinic crystals, so I cannot tell you what it looks like. Malachite is opaque (light does not pass through it) and it is often found with azurite, which is another copper mineral.
     Malachite has been used as a copper ore for some time and still serves as one today, but it is not used as often as other ores since malachite is also a decorative stone. Malachite’s banding makes it a popular stone to polish for such applications as cabochons, slabs, and boxes as well as carvings. It is used to make jewelry, but its polish will scratch very easily as it is very soft. Malachite can also be crushed to make pigment.
     Malachite can be found wherever copper is mined or exposed to the air (you can probably find malachite under your sink if your pipes are slightly corroded) Some places where malachite can be found in the ground and in the rocks are Arizona, Russia, Zaire, and Namibia.
     Malachite is one of the fastest-forming minerals that I know of. Simply place a piece of copper outside, let it get rained on a little, and you’ll have malachite growing after a little while. It might seem strange to say it, but rust can be beautiful!

Pumice: the Rock that Floats

     Have you ever heard the phrase, “sink like a rock?” I am sure that you have, and it makes sense, because most rocks are so dense that the idea of one of them floating would seem completely ludicrous. However, you will soon see that the phrase, "sink like a rock" does not ring true in the case of every rock.
     Pumice is a natural glass that is formed by volcanoes. When molten rock erupts from a volcano it can form a number of different rocks under different circumstances. Sometimes when this molten rock cools quickly it forms natural glass, a substance that is a lot like the glass that we use for making jars and windows, but is made by natural processes, like obsidian. Pumice is formed this way, but unlike obsidian, which is dense and has very sharp edges, pumice is filled with bubbles of gas and is very light. When this gas escapes the bubbles leave a lot of tiny void spaces in the rock and thus pumice is formed. Pumice has no regular shape, but is rather found as amorphous pieces of hardened lava-froth. Pumice is usually white or gray in color, but other color varieties do exist. The color of pumice really depends upon what kind of rock was melted to make it. Pumice that is composed mostly of rhyolite or trachyte is white, pumice that is composed mostly of andesite is yellow or brown, and pumice that is mostly composed of basalt is pitch-black. As I have said before, the bubbles found in pumice make it very lightweight. Pumice is so light, in fact, that it will actually float in water!
     Pumice is used to make gentle abrasives such as Lava Soap, a brand of liquid hand soap that contains small pieces of pumice that help to scrub grime off of one’s hands. You can buy blocks of pumice to remove calluses from your feet, as the porous volcanic glass will act as sandpaper against the dead skin while having no ill effect on your living tissue other than some minor discomfort. One interesting use for pumice that I have seen is as a landscaping stone. At the gardening section of a certain hardware store I once saw boulders of pumice for sale that measured about two feet across. They were supposed to imitate other sorts of stones in landscaping applications. These were somewhat comical, because while they looked like small boulders I could lift them with ease.
     Being a volcanic rock pumice can be found, theoretically, wherever volcanoes are present. There are large sources of pumice, however, which include: Italy, Turkey, Spain, Greece, and the United States in the Rocky Mountains and the Pacific Coast. Interestingly, pumice can sometimes travel far from its source. Since pumice can float on water for months before it becomes waterlogged and sinks, any pumice that was formed near the ocean can drift to wherever the currents may carry it. After the eruption of Krakatoa large pieces of pumice floated about in the Indian Ocean for months. The pumice from Krakatoa floating about in the ocean actually posed a hazard to ships for a little while afterword.
     Pumice is certainly one of the coolest rocks that I know of, after all, how many rocks do you know of that can float? Perhaps rock and mineral collectors can coin a new phrase, “sink's like most rocks.”

Chrysoprase, the Gem of Kings

     Chrysoprase is an apple-green variety of the mineral chalcedony. Chalcedony is a variety of microcrystalline quartz (that is, quartz that is composed of a lot of tiny crystals as opposed to a single large crystal) Chrysoprase gets its green color from nickel impurities. This color can fade when chrysoprase is heated and when it is displayed in direct sunlight, so if you happen to have a piece, don't display it in the sun for prolonged periods of time! Being microcrystalline chrysoprase has no shape, but rather is found as veins and nodules. Once source of information that I read said that chrysoprase belongs to the hexagonal crystal group, but I believe that that description refers to the tiny crystals that make up its mass and not to the mass itself. Chrysoprase is translucent, but can be nearly opaque and while chrysoprase is known for its common apple-green color it can also be yellow-green in rare occasions.
     Because of its attractive color chrysoprase has been used as a gemstone since ancient times. Chrysoprase is still used as a gemstone today.
     Possibly the most famous source of chrysoprase is the region of Silesia in Poland. This source has been used since medieval times and some of its gems were used to make jewelry for kings, most notably King Frederick II of Prussia. King Frederick even discovered a vein of chrysoprase there that was three miles long! Since the source in Poland has been just about exhausted the market has turned to other sources. Today most chrysoprase comes from Australia. Other sources include: Russia, Germany, Tanzania, Kazakhstan, Japan, Arizona, and California.
     I think that chrysoprase is a beautiful stone, and it appears that others agree! Chrysoprase has been used by the Ancient Egyptians, the Ancient Greeks, the Romans, and the king of Prussia. However, One greater than all of those previously mentioned has made use of chrysoprase as well. In the book of Revelation God has revealed to us that He plans to use chrysoprase as a foundation in the New Jerusalem. Chrysoprase is truly the gem of kings, and of the King of kings!

Mica: a Shining Star

     The term "mica" actually refers to a group of minerals. These are part of a group of minerals geologists call “rock forming minerals” because they are one of the main components of many types of rocks. Certain types of granite, for instance, contain micas.
      Micas are chemically similar and all possess similar properties. Their crystals are made up of many layers of thin sheets that resemble the pages of a book and can be split very easily. Mica crystals are technically monoclinic, which, without the scientific definition, means they have ten faces, are very thin, and look somewhat like two keys from a desktop-computer’s keyboard fused at the base to make a single shape. These crystals usually have six sides. In rare cases people have found mica with twinned crystals that looked like five-pointed stars. However, micas are so soft that their six-sided, monoclinic shape is often distorted, or at least all of the specimens that I found had been. Individual mica crystals can be very large, the largest ever found measured thirteen feet across! The color of different mica minerals depends on their chemical composition. While there are currently more than twenty micas identified, I wall only cover the most common: muscovite is usually colorless, but is sometimes pale green; biotite is jet-black, phlogopite is colorless or brown, and lepidolite is violet-pink. Mica also has a very reflective surface. I learned this first-hand while driving through a campground at night in a place where small fragments of mica littered the ground. As the light from the car headlights struck the pieces of mica they seemed to glow. At the time I did not know a great deal about mica and it wasn’t until the next morning that I found out what the little glowing things were!
     In industry large sheets of mica are called sheet mica, and small flakes are called flake mica or scrap mica. Sheet mica was once used to make machine parts since it is not flammable, but I think that other substances have replaced it in that application by now. In today’s industry sheet mica is used as an insulator in electrical applications because it does not conduct electricity. Given mica’s shiny surface, flake mica is ground and used to give wallpaper a shiner luster. Perhaps the most interesting use that I have seen for mica comes from the Muscovy province in Russia. There, people once used large sheets of muscovite mica (which was named for the province, by the way) as a substitute for glass in the windows of their homes!
     Since they are rock-forming minerals, micas are found all over the world in igneous, sedimentary, and metamorphic rocks. Some good sources of sheet mica include: India, Brazil, and Madagascar. Some good sources of flake mica include: North Carolina, New Mexico, and South Dakota.
     Because it is used in today’s industry and is one of the major components in many rocks, the micas are certainly important minerals. Some are quite literally shining stars!

Amber: God's Snapshot of the Past

     This might come off as a bit surprising, but amber is not a mineral! Amber is not a rock either. What is it then? Amber is actually hardened tree-sap or resin. If you can remember that song Modern Major General, and the line, “I’ve information vegetable, animal, and mineral,” amber would fall under the "vegetable" category. If you wonder why it is that I have chosen to write about a substance that is neither rock, nor mineral the answer is that there are a few reasons. Amber is somewhat like a mineral, it is used as a gemstone, and it is technically considered a fossil, the third topic of the blog.
     Amber is formed by some chemical processes that take place within resin as it hardens. These are somewhat complex and I don’t plan to talk about them here. Amber has no crystal structure, but rather forms as amorphous blobs. Amber is often a honey brown color (this color is also called "amber"), but it can also be yellow, orange, red, brown, blackish-brown, clear, white, and even blue or green! Amber can either be translucent or opaque; the translucent variety resembles glass and the opaque variety resembles plastic. Cracks that occur in amber can cause what is known as spangling, which looks like paper-thin saucers trapped inside of the amber (you can see this in the picture) Amber is also famous for its insect inclusions, which are caused by insects becoming trapped in the resin while it was still a sticky gel. Other inclusions that were formed the same way have been found, however, such as: wood fragments, pollen, seeds, leaves, flowers, spiders, scorpions, bird feathers, and small lizards!
     Amber has been used as a gemstone for thousands of years. The Romans, Ancient Greeks, Ancient Chinese, Vikings, and the Slavs of ancient Poland all used amber to make jewelry. Today amber is still used for this purpose. Amber is used to make beads, pendant carvings, or simply polished in its natural shape. Amber is often polished in a way that allows you to see the inclusions within it. Another way that amber is used as a gem is to make what is known as ambroid. Ambroid is made by heating and compressing small pieces of amber until they stick together to make one large piece. Low-grade amber is used in industry to make certain varnishes and lacquers.
     Amber is found all over the world, but large deposits of amber are sparsely distributed. One of the most famous sources of amber is the coast of the Baltic Sea. Amber can be found along the sea in places such as Poland, Lithuania, Sweden, Norway, and Germany. Since amber floats on salt water, Baltic amber has drifted to places as far from its original source as the Netherlands, and even the island of Britain. Other sources of amber include: the Dominican Republic, Mexico, Spain, Romania, and Canada.
     Of all the things that are known of amber, I am willing to bet that the inclusions that it boasts are the most famous. It is for this reason that I call amber God’s snapshot of the past.

Agate: The Mineral With Rock-Bands

     Agate is a type of chalcedony that is known for its banding. Chalcedony is a variety of quartz in which tiny quartz crystals are packed closely together. Agate is a type of chalcedony in which there are layers of alternating shades or colors throughout the stone. If the agate is cut correctly these bands appear similar to the planet Saturn's rings. Agates are often found as amorphous lumps, rounded stones, or the linings of geodes. These geode-lining agates sometimes have quartz crystals of a slightly larger size at their centers. Agates are usually sliced to reveal their banding. No two agates are exactly alike, but most agates do exhibit similar patterns of banding. Different kinds of patterns have their own names, and I thought that it would be good to cover some of these. One type of agate has a pattern that reminds some people of the map of a hill fort; these are called fortification agates. Others have inclusions that look like green moss; they are called moss agates. A similar kind of agate has inclusions that look like the silhouette of trees and shrubs, which are called landscape agates. Agates that have individual, little swirls among the other larger swirls (somewhat like the planet Jupiter’s Red Spot) are called eye agates. An iridescent type of agate is known as fire agate. There are many other varieties of agate, but to describe them all would take the space of another blog!
     Agates are very popular as gemstones as they are hard enough to resist wear and scratching and also very beautiful. Agates are often cut en cabochon and set into mounts, but they are also made into cameos or simply polished as slabs. Agate has been a popular carving medium since ancient times (in a book about the Byzantine Empire I saw a goblet that was carved from agate) and the mineral is still used for carving today. Today agate is used to make…well, anything that you might want to carve. One carving that I have seen  in this age is a bookend. Slices of agate, which are translucent, are also used to make the coverings for decorative night-lights and fancy lampshades.
     Being a quartz-mineral agate is found worldwide throughout the Earth’s crust. Some of the best sources of agate include: Brazil, Uruguay, Germany, China, Egypt, and the coastline of Lake Superior.
     Agate is surely a fascinating mineral. Believe it or not agate is actually mentioned in the Bible! Agate is one of the twelve stones that God commanded the Israelite priests to wear on their breastplates (Exodus 28:19) God’s telling His people to use a piece of His creation in their worshiping Him is further proof that God is pleased with His creation!

Wavellite: The Grape Mineral

     Wavellite is a mineral that has an unusual shape and an unusual description. Wavellite can be defined both as a “phosphate mineral” and as a “secondary mineral.” A phosphate mineral is a mineral that contains a phosphate ion (PO4) which is composed of the elements phosphorous and oxygen. There are hundreds of phosphate minerals on the earth. A secondary mineral is a mineral that was formed by the chemical alteration of another mineral. Simply put, when one mineral undergoes a chemical reaction and changes its chemical makeup to form a new mineral, this new mineral is called a secondary mineral.
     Wavellite crystals are almost always acicular (needle-shaped), but these needle-like crystals often form some of the most interesting mineral aggregations that I have ever seen. Wavellite crystals are often found bunched together as radial sprays (crystals that radiate from a central point like sunbeams), hemispheres, and spheres. When broken open these spheres and hemispheres have a radial appearance that is similar in appearance to the cross-section of a Popsicle.
     Wavellite spheres often remind me of a bunch or grapes because they are often packed so closely together. It is because of this fact (which is called a botyroidal habit) that I call wavellite the "grape mineral."  The fact that they often display a green color doesn’t hurt the idea either!
     Wavellite serves only one major use outside of mineral collecting and that is as an ore of the element phosphorous. Phosphorous is a non-metallic chemical element that is found in Group VA of the Periodic Table. In modern industry phosphorous is used mainly to make safety matches and a chemical called phosphoric acid.
     Wavellite is found in Australia, England, Germany, France, and many parts of the United States of America.
     I find wavellite an interesting specimen because of its chemical composition and because of its grape-like appearance. If my specimen was any larger I might have to resist the temptation to bite it!