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!