Tuesday, November 30, 2010
Aragonite, the Mineral With a Patriotic Name
Aragonite is named for the Spanish province of Aragon. Aragonite crystals can be fibrous, acicular (needle-like) or prismatic, but they often display what is known as crystal twinning. Crystal twinning is a mineral phenomenon in which crystals grow together and sometimes appear as one. In the case of aragonite these crystals can form as columns or large needles that radiate from their base. Aragonite can also form as stalactites. As is the case in many mineral types aragonite is clear when pure, but impurities can cause it to become yellow, blue, pink, green, brown, orange, and rarely purple. Aragonite can be confused with the mineral calcite, but it can be easily distinguished by its greater specific gravity. The specific gravity loosely defined is the ratio of a mineral’s weight to its size. Minerals with a higher specific gravity feel heavy for their size. So a piece of calcite will weigh less than a piece of aragonite that is the same size.
Aragonite has some use in jewelry, but due to aragonite’s softness this use is limited. Aragonite is used to make beads and small carvings. Aragonite is sometimes polished though I cannot elaborate on what it looks like polished because I have never seen it. However, I have seen a polished slice of an aragonite stalactite that was quite pretty. The picture that I saw had alternating layers of white, yellow, brown, and orange. The layers were uneven and looked as if they had been folded. Aragonite is also used in the making of cement and in glass-making applications. Aragonite is composed of a chemical that is called calcium carbonate, which is used to neutralize acid in industry. Aragonite is also used to make calcium-rich fertilizers for agriculture, animal feed, and white pigments.
Aragonite is found in many places, but I personally doubt that any source can be considered more famous that that of Aragon, Spain. Aragonite is also found throughout the western Mediterranean region, England, Colorado, Mexico, Russia, the Czech Republic, and Australia. Though I did not come across this source an any of the books that I read I have known New Mexico to be a good source.
Aragonite is certainly a captivating mineral and I am glad to have learned so much about it. Also aragonite inspires the idea of naming a mineral that one discovers after the region in which he or she lives. If ever you come across a blog about the mineral michiganite, you’ll known that I’ve done just that!
Saturday, November 27, 2010
Quartz, the World's Most Common Mineral (Part Four--Quartz With Inclusions)
Quartz, the World's Most Common Mineral (Part Four--Quartz With Inclusions) is the final installment of the series of blogs that I've written about the subject of quartz. I hope that by the time that you have come to this final piece I hope that you have gained a great deal of knowledge about the world's most common mineral!
I have already covered inclusions, but for those who have not read the blog in which this information can be found I will touch onto the subject again. When a mineral is said to have an inclusion that means that something else is trapped inside of it. This could be a bubble of gas or liquid, or it could be an entirely different mineral. Inclusions are fairly common in quartz and while bubbles and vesicles are common we will focus mainly on other minerals being trapped inside of quartz.
The first inclusion that I will mention is that of black tourmaline. Black tourmaline crystals are often prismatic or acicular (needle-like) in shape. When quartz contains inclusions it is often given different names. Quartz containing tourmaline is called tourmalinated quartz. Possibly the most famous quartz inclusion, crystals of rutile are common in quartz as well. Rutile crystals are almost always acicular and are usually red, black, or metallic yellow in color. Quartz with rutile inclusions is called rutilated quartz or sagenite. Quartz can contain gold (gold-bearing quartz is known as “gold quartz”) and silver. Silver inclusions are often dendrites and are usually silver of black in color. Quartz has also been known to the iron-bearing minerals pyrite and goethite. I have found one piece that I believe might contain hematite, but I am not sure if it is truly hematite or another iron mineral. I have also found quartz that contains what I think is biotite mica, but again I am not completely sure.
Quartz with inclusions serves only two uses that I know of: carving stones and a collector’s pieces. Quartz with inclusions can make very interesting carvings because of the appearance that the crystals found inside of it may bestow. Many rock and mineral collectors love quartz with inclusions because it is breathtaking to look at perfect crystals that are completely enclosed within another crystal.
Again quartz can be found anywhere so quartz with inclusions can be found anywhere hypothetically. I have found samples of quartz with inclusions in South Dakota, New Hampshire, and Michigan. Other sources include: Madagascar, Brazil, South Africa, India, Sri Lanka, Germany, and Switzerland.
Like all minerals, I think that quartz with inclusions display the artwork of God. After all, there is no rear reason why one mineral should form within another; it is simply another wonder of creation. Perhaps the real purpose of minerals like quartz with inclusions is to draw our minds into a state of thankfulness toward our Creator, who could have made the earth a drab and dull place, but chose to fill it with wonder instead. Let us thank Him for this gift today!
Wednesday, November 24, 2010
Quartz, the World's Most Common Mineral (Part Three--Brown Quartz)
So, by this time we have read about quartz that is clear, white, and pink, but did you know that there are still other colors and varieties of quartz out there? Indeed there are, and today we will focus upon a group of quartzes that have been dubbed brown quartz.
I assume that most people probably think that brown quartz is brown in color, and that is partly true: some of it is. Other colors that fall under the brown quartz category are grayish brown and black-colored. Quartz that is brown, light brown, or grayish brown is called smoky quartz, and black quartz is called morion. Brown quartz is also called cairngorm when it is found in the Cairngorm Mountains in Scotland. No one knows for sure exactly how brown quartz is formed, but scientists have observed colorless quartz crystals become brown when exposed to radiation. This has led many scientists to adopt the theory that brown quartz was given its color by exposure to natural radiation. I do not know of any properties of brown quartz that are too different from that of its colorless counterpart, save for its brown color. Brown quartz grows with the same crystal structure that colorless quartz follows, and very large crystals at that. In Brazil people have found crystals of brown quartz that weighed as much as 650 pounds!
Brown quartz is used mainly as a decorative stone. It is used to make carvings and cameos and occasionally it is used as jewelry. Morion is black, so I imagine that it has been used to make morning jewelry, but I have never heard whether or not this is true. Brown quartz, like any mineral, is also prized by collectors. One important thing to know is that a great deal of the brown quartz that is on the market today was produced artificially by exposing rock crystal quartz to radiation.
Like all quartz, brown quartz could be found anywhere on earthy, but it is usually found in certain locations. Some of the best locations in which brown quartz is found are Brazil, Madagascar, the Swiss Alps, and Colorado.
Monday, November 22, 2010
Quartz, the World's Most Common Mineral (Part Two--Rose Quartz)
Rose quartz is a member of the quartz family of minerals. Its chemical makeup is the same as that of colorless quartz and it possesses most of the same properties, though it is different in the fact that it is very brittle and does not usually from as crystals, but as massive lumps. As its name might imply rose quartz is pink in color; this color is thought to be the product of titanium impurities, which makes sense to me because rutile, a titanium mineral, is found inside quartz crystals very often! Rose quartz is almost never transparent because it is usually filled with cracks, but every piece that I’ve seen has been translucent. When something is called translucent that means that it allows light to pass though it, but one cannot see through it.
Rose quartz has little use outside of rock and mineral collecting. It is occasionally used as jewelry, but it is not very popular. Rose quartz is also used to make decorative carvings, and, like its colorless counterpart, is occasionally used in landscaping.
Rose quartz possesses one very interesting quality, which I think is worth mentioning here. If you have two pieces of rose quartz, try taking them into a dark room and ramming them together rapidly for a few moments. Eventually they will start to spark when they collide. Though the are many interesting aspects of rose quartz, I have to say that this is my favorite!
Since it is a quartz mineral, rose quartz could theoretically be found anywhere in the earth’s crust. However if you want the highest quality pieces the place to find them would be Madagascar, but it can be found in greater quantities in Brazil. Other sources include Spain, Scotland, and the former USSR. Colorado is a good source of rose quartz in America and I own some pieces that I believe to be from Arizona. Whether or not rose quartz is found in the next location that I am about to mention, I do not know, but if you want to buy rose quartz there is no better place on earth (in my opinion) than Custer, South Dakota. There are many rock and mineral shops in that area and there I saw tables laden with boulders of rose quartz twice the size of bowling balls! I like rose quartz and am glad that our Creator chose to create it!
Wednesday, November 17, 2010
Quartz, the World's Most Common Mineral (Part One--Colorless or White Quartz)
Quartz is the most abundant mineral in the earth’s crust and is found everywhere in the world. Many rock collectors have probably started their collections with quartz because it is very common, and therefore can be found easily or purchased at a very low price. Today’s blog will focus upon what is probably the most famous sort of quartz, colorless and white quartz. Pure quartz is colorless, in fact some crystals are as clear as glass. Colorless quartz is called “rock crystal.” Quartz crystals are hexagonal with pyramidal ends, but, like many minerals, quartz is often found as broken pieces, water worn pebbles, and massive agglomerations. I have personally seen a boulder of quartz that measures about two feet across, but even larger specimens have been found. Quartz can also be reduced to very tiny pieces as well. In fact, most white or beige-colored beach sand is composed mostly of tiny grains of quartz. Quartz can also be given a milky white appearance by tiny bubbles of gas and liquid that have been trapped within the stone. This quartz is called “milky quartz.”
Quartz serves a variety of uses, some of which are in jewelry, but most are less glamorous. Clear quartz can be faceted and used as a gemstone, but it is very common and therefore not as desirable as some rarer rocks and minerals. Quartz is more often tumbled to make lumpy polished stones that are sold for a fairly low price or carved as beads, cameos, or small statues. Quartz has been used as a building stone in years past, but it has been replaced by brick and was never the most prominent building stone anyway. Quartz breaks with what is called a conchoidal fracture (that means that when quartz chips or breaks its chips resemble conch shells) and can therefore be honed into a very sharp edge and be used to make tools and weapons. I came by an arrowhead that was made of milky quartz in the Stanton, Michigan area (pictured) It was made by Native Americans long ago and is a good example of the use of quartz as a tool-making material. Quartz is also used in modern landscaping to make walkways or any other area requiring a blanketing of stone, and larger quartz pieces can be used as centerpieces in landscaping applications. Quartz can also be used in watches and precision instruments as well as lamps. When melted and mixed with other compounds quartz is used to make glass. Quartz is also a source of the metalloid chemical element silicon, which is used to make microprocessor chips in computers and other devices. Because of its hardness quartz can also be used as an abrasive.
Quartz is found everywhere as it is the most abundant mineral in the earth’s crust. The best sources of rock crystal include Brazil, the Alps in France and Switzerland, and the USA. I have personally seen a great deal of rock crystal quartz in its natural state in the vicinity of Custer, South Dakota. Though quartz may be the most common mineral in the world it is certainly not the least fascinating!
Monday, November 15, 2010
Zircon, a Source of Exotic Metals and a Source of Delight
Zircon is a mineral that receives its name from the Arabic word zagrum, which is derived from the Persian word for “gold colored”. Indeed, some zircon is honey-brown in color, but light blue, light green, yellow-green, blue, and clear varieties are also common. Zircon crystals are tetragonal, but many zircon samples are found as broken pieces, water worn pebbles, and large stepped crystals. A stepped crystal is a crystal that exhibits different layers that extend further than one another like a tiny staircase. Zircon crystals can also be damaged by the decay of tiny amounts of the radioactive metals thorium and uranium that are found within them. Zircon crystals that have been damaged by radioactive decay are said to have a metamict structure. Metamict zircons are also known as “low” zircons.
Zircons also display some curious optical properties. Colorless zircons can exhibit a fire more brilliant than that of a diamond and some zircons will also reflect light in such a way as to display a rainbow-colored flash within them. The color of a zircon can be changed by heating it and zircon can sometimes display what is called mineral fluorescence. Minerals that display mineral fluorescence (which are called fluorescent minerals) actually appear to change color and glow beneath an ultraviolet or black light and will even glow! I have personally seen my own sample of zircon become pink and glow under an ultraviolet light. There are a great many minerals that possess interesting optical properties, but it is safe to assume that zircon just might have out-classed all of them!
Zircon is also a very useful stone. Zircon has been used as a gemstone for a great deal of time (it has been used in India for centuries) Colorless zircon can be used to imitate diamonds, but zircons can be distinguished from diamonds by their more brilliant fire, and the fact that zircons will chip and scratch while diamonds will not. Zircon also has a number of industrial and technological uses. Great amounts of zircon can be used to make ceramics, firebricks, and molds for metal casting. The metal zirconium was discovered within (and named for) zircon and the stone serves as the chief ore of zirconium today. Zircon also serves as a source of hafnium and thorium as well. Zirconia (zirconium oxide) can be extracted from zircon. Zirconia can be used to make cubic zirconia, which is used to imitate diamonds.
Zircon has been mined in Sri Lanka for about two thousand years. It is also found in Myanmar, Thailand, Cambodia, Vietnam, Brazil, Nigeria, France, the Australian state of Tasmania, and the American states of Florida and Georgia. Zircon is both an ore stone and a gemstone as well as an interesting collection piece. It ranks among the most interesting of minerals in the scientific respect in my opinion.
Friday, November 12, 2010
Lapis Lazuli, Rock On!
It’s finally time for my first blog about a rock and not a mineral. Lapis lazuli is a blue rock that has been prized since ancient times. What makes a rock differ from a mineral? you may ask. A mineral is an inorganic substance with a definite chemical formula. A rock is simply a mixture of minerals. You can think of a mineral as a simple substance such as sugar or salt and a rock would be a mixture of other substances like a cake or salad dressing. Lapis lazuli is a rock that is composed of the minerals lazurite, sodalite, hauyne, calcite, and pyrite. Lapis lazuli receives its blue color from the mineral lazurite and the pyrite present within the rock will sometimes dot the stone with brassy flecks. The mineral calcite is sometimes visible as streaks of white material throughout the rock. Being a rock lapis lazuli has no crystal structure, but is instead found in giant amorphous lumps. The word amorphous means ‘without shape’ or ‘no shape’ and means that the thing in question has no definite shape and is found in random chunks. A few minerals have been known to form amorphous specimens, but these huge lumps are composed of a great deal of tiny crystals that all have definite shapes. Lapis lazuli has no definite shape because it is a mixture of minerals.
I only know of a few uses for lapis lazuli. The first is as a decorative stone. Lapis lazuli has what I would call a medium hardness (it measures about 5 ½ on the Mohs’ Scale) so it can be carved and polished fairly easily. Both the ancient Egyptians and the Babylonians used lapis lazuli to make carvings. I have personally seen photographs of mosaics, scarabs, and figurines that were made from lapis lazuli in ancient Egypt. Tutankhamen’s mask was inlaid with the stone as well. Lapis lazuli was also ground to make a blue-colored paint in ancient Persia, though this was a very rare use of the rock because the mineral azurite was softer and a lot less expensive than lapis lazuli. Today Lapis lazuli is still used to make carvings and rock and mineral collectors also love to have natural, un-carved, pieces in their collections.
Lapis lazuli is found in Argentina, Chile, the former USSR, and the United States. The most famous source of the blue rock is Afghanistan where it has been mined for thousands of years. Most of the lapis lazuli that was used by ancient peoples probably came from Afghanistan. In fact, the lapis lazuli that is found upon King Tutankhamen’s mask came from that country.
Lapis lazuli is beautiful when compared to most other rocks, and even when compared to some minerals. It is certainly the only blue rock that I know of!
Wednesday, November 10, 2010
Hi-Ho Silver!
Silver is a silver-colored metal that is found between copper and gold on the Periodic Table of the Elements. It is very soft and tarnishes easily in polluted air; silver is also the best conductor of both heat and electricity among all of the metals. Now, by this time I am sure that you are beginning to wonder why I thought to include silver in a blog about rocks and minerals. After all silver is neither a rocks nor a mineral: it is an element, one of the building blocks of minerals. A great deal of the elements do not occur uncombined in nature, they are always found as compounds and must be extracted. There are some elements that do occur in pure, solid form not combined with any other elements. These are called native elements, and native elements are sometimes classified as minerals. These include: copper, gold, sulfur, bismuth, and silver.
Native silver is often found as natural wires or as dendrites, and it is occasionally found as nuggets. The term dendrite refers to a crystal that grows like the branches of a tree. Native silver is found as these tree-like structures, as is native copper. In Michigan’s Copper Country native silver and native copper are sometimes found growing together! These crystals are quite rare and are prized by collectors.
No one knows when people first began to use silver, but I am willing to guess that they might have done so right out of the Garden of Eden. Since silver is soft, melts at a lower temperature than many metals, and is found as a native metal, silver has always been a popular metal to craft objects from. Silver was, and still is, used to make decorative objects and jewelry. Since silver is so soft and will tarnish easily other metals are often added to it to keep it from wearing out or tarnishing. When 20-25% silver is added to gold the alloy is called electrum. When 7.5% copper is added to silver the alloy is called sterling silver. At the end of the Middle Ages silver was valued as highly as gold, but now an ounce of silver is worth about fifty to eighty times less than gold, though it is still quite valuable when compared to other metals. Silver has also been used to make coins for quite some time, but most countries no longer use precious metals like silver to make their coins. Silver possesses greater electrical conductivity (the ability to allow electricity to pass through it) than any other metal. In fact, when the electrical conductivity of a metal is judged it is actually measured against silver. Because of this silver is used in some electrical applications, specifically those in which the need for perfect conductivity outweighs the cost of silver!
Silver is found in many places throughout the world, but it is usually found as an ore. The best sources of native silver include China and Michigan’s Upper Peninsula. Historically Norway has been the best source of native silver. A good deal of native silver was found at Kongsberg, Norway in the 17and 1800s.
Silver, both a metal and a mineral, is as useful as it is beautiful. Now I know why it is so valuable!
Native silver is often found as natural wires or as dendrites, and it is occasionally found as nuggets. The term dendrite refers to a crystal that grows like the branches of a tree. Native silver is found as these tree-like structures, as is native copper. In Michigan’s Copper Country native silver and native copper are sometimes found growing together! These crystals are quite rare and are prized by collectors.
No one knows when people first began to use silver, but I am willing to guess that they might have done so right out of the Garden of Eden. Since silver is soft, melts at a lower temperature than many metals, and is found as a native metal, silver has always been a popular metal to craft objects from. Silver was, and still is, used to make decorative objects and jewelry. Since silver is so soft and will tarnish easily other metals are often added to it to keep it from wearing out or tarnishing. When 20-25% silver is added to gold the alloy is called electrum. When 7.5% copper is added to silver the alloy is called sterling silver. At the end of the Middle Ages silver was valued as highly as gold, but now an ounce of silver is worth about fifty to eighty times less than gold, though it is still quite valuable when compared to other metals. Silver has also been used to make coins for quite some time, but most countries no longer use precious metals like silver to make their coins. Silver possesses greater electrical conductivity (the ability to allow electricity to pass through it) than any other metal. In fact, when the electrical conductivity of a metal is judged it is actually measured against silver. Because of this silver is used in some electrical applications, specifically those in which the need for perfect conductivity outweighs the cost of silver!
Silver is found in many places throughout the world, but it is usually found as an ore. The best sources of native silver include China and Michigan’s Upper Peninsula. Historically Norway has been the best source of native silver. A good deal of native silver was found at Kongsberg, Norway in the 17and 1800s.
Silver, both a metal and a mineral, is as useful as it is beautiful. Now I know why it is so valuable!
Monday, November 8, 2010
Rubies: World's Most Valuable Gem
Rubies are a red variety of the mineral corundum. Pure corundum (a form of aluminum oxide) is colorless, but different impurities can alter the mineral’s color. Rubies are turned red by impurities of iron and chromium. Rubies can be any shade of red including pink, purple, and reddish brown, but a bright red is the most desirable. Ruby crystals usually form as hexagonal prisms with flat or tapered ends. However rubies are not always found as these perfect prisms, but as rounded pebbles in gem-rich gravels in gravel pits and river beds. Ruby crystals often form crystal twins when they grow naturally and will sometimes fracture because of it. Crystal twinning is a term used to describe a growth pattern in crystals in which two or more crystals appear to intersect one another symmetrically. Other than twinning rubies are also known to display what is called asterism. Asterism is a phenomenon that occurs in some crystals because of the stones’ internal features such as cavities or fibrous crystal inclusions. When the light reflects off of these cavities or crystals a star shape appears in the stone (this is most visible when the stone is cut en cabochon --cut and polished with a domed surface like a lens) When a stone has two sets of parallel crystals a four-rayed star is produced. When there are three sets of parallel crystals present a six-rayed star is produced (this continues onward!) Rubies also display what is called zoning. Ruby crystals grown in layers and sometimes the layers can be different shades of the same color. When different color variations are present in the same crystal this is called zoning.
Rubies are a rare and valuable type of gemstone so they are used mostly in jewelry. Rubies are very hard (second only to diamonds in their hardness), they are a very attractive color, and are quite rare, so they are good candidates for the gem industry. This may be hard to believe, but gem quality rubies are actually the most valuable gemstone in the world, worth more than diamonds of the same size! Besides gemstones rubies have some industrial uses. Because they are so hard, tiny rubies or very small pieces leftover from gem cutting are used to make emery boards and some kinds of sandpaper (or emery cloth). Rubies are also used in medical lasers and some watches.
Rubies that are not of gem-quality are found in many parts of the world, but true gem-quality rubies are found only in certain places. Myanmar is probably the most historical source, but nowadays most rubies come from Thailand. Most Thai rubies are brownish red in color. The best bright red rubies come from Afghanistan, Pakistan, and Vietnam. Opaque rubies are found in Norway, Russia, India, Australia, and North Carolina. I think that their beautiful red color can be a reminder of the undeserved gift of our Savior’s blood that was spilled on our behalf. With this in mind one can think that rubies are very special stones!
Rubies are a rare and valuable type of gemstone so they are used mostly in jewelry. Rubies are very hard (second only to diamonds in their hardness), they are a very attractive color, and are quite rare, so they are good candidates for the gem industry. This may be hard to believe, but gem quality rubies are actually the most valuable gemstone in the world, worth more than diamonds of the same size! Besides gemstones rubies have some industrial uses. Because they are so hard, tiny rubies or very small pieces leftover from gem cutting are used to make emery boards and some kinds of sandpaper (or emery cloth). Rubies are also used in medical lasers and some watches.
Rubies that are not of gem-quality are found in many parts of the world, but true gem-quality rubies are found only in certain places. Myanmar is probably the most historical source, but nowadays most rubies come from Thailand. Most Thai rubies are brownish red in color. The best bright red rubies come from Afghanistan, Pakistan, and Vietnam. Opaque rubies are found in Norway, Russia, India, Australia, and North Carolina. I think that their beautiful red color can be a reminder of the undeserved gift of our Savior’s blood that was spilled on our behalf. With this in mind one can think that rubies are very special stones!
Friday, November 5, 2010
Diamonds: Are They Really Forever?
Diamonds are the hardest mineral on earth; they cannot be scratched by anything except other diamonds. Diamonds are one of the four allotropes of the element carbon. When elements are said to have different allotropes that means that they can exist in different forms. There are four known allotropes of carbon: graphite, amorphous carbon, fullerenes, and diamonds. Solid allotropes exist as different crystal structures and diamonds are the strongest crystal structure present in carbon. Diamonds are formed in the earth’s mantle (about ninety miles below the earth’s surface) where heat and pressure arrange carbon atoms to form a compact structure. This compact arrangement of atoms is the source of the diamond’s hardness and its shape. Diamond crystals are usually octahedral like the mineral fluorite, but they have rounded edges and convex faces. Diamonds are brought to the earth’s surface by volcanic eruptions and are often found in volcanic rocks, most notably kimberlite. Diamonds often make their way into rivers where they are sometimes mistaken for worthless pebbles!
As I said before, diamonds are the hardest mineral on earth. The only way to cut a diamond is to do so with another diamond, such as a diamond wheel or a diamond drill. Diamonds will not be broken down by acid either. Because they are so hard and acid will not dissolve them diamonds are often thought to be indestructible. That is why they are so often used as a symbol of marriage because “diamonds are forever.” Unfortunately this is not true. While it is impossible to scratch a diamond with anything other than another diamond there are ways to destroy them. Since they are nothing more than carbon, diamonds will burn (anybody see the movie Fireproof?) Diamonds can also be broken if they are struck with a sharp, hard blow. The most popular use of diamonds is that of jewelry. Diamonds are the symbol of engagement, as well as the official gemstone of 10th and 60th wedding anniversaries. Clear, flawless diamonds are the most popular, but black, green, pink, gray, red, and blue varieties also exist. As gemstones diamonds are graded by the “Four C’s:” cut, clarity, color, and carat. As well as their hardness diamonds also have a brilliant “fire” and luster. Other than as gemstones diamonds are used in industry, where their extreme hardness makes them very valuable cutting tools. Diamonds are used to make polishing wheels, drills, and saws. Lower-grade diamonds are usually the ones used in industrial applications because they cost considerably less. The least expensive diamonds that are often used include black or “bort” diamonds and a microcrystalline variety of diamond called carbonados. The term microcrystalline refers to a mineral that exists as a giant mass of tiny crystals instead of one large crystal. Jasper is a microcrystalline variety of the mineral quartz. Carbonados are composed of many tiny diamond crystals and are used mainly in industry due to their unattractive appearance.
Diamonds are found in many African countries such as: Ghana, Sierra Leone, Zaire, Botswana, Namibia, and South Africa. They are also found in the former USSR and the United States. Today most diamonds come from Australia.
Diamonds are certainly interesting stones, after all nothing on earth can scratch them (save for other diamonds), acids have no effect on them, and it requires great force to break one. But remember, as hard as they are diamonds are not indestructible. Wednesday, November 3, 2010
Fluorite, the Mineral that You've Probably Eaten!
Fluorite, which was once called fluorspar, is a very soft mineral. On the Mohs’ Scale, which is a scale of mineral hardness that goes from 1(softest) to 10(hardest), fluorite measures at only 4. Fluorite has been used for many years and for many different purposes. It is still widely used today and you may have ingested some without even knowing it!
Like many minerals fluorite can have many colors. Fluorite can be yellow, purple, green, clear, or blue. Like tourmaline, single fluorite specimens can display more than one color, but unlike tourmaline which does so in an orderly fashion, when fluorite displays different colors it is usually banded and has many layers of alternating colors. When fluorite forms as a banded mixture of blue and yellow it is called “blue john.” Fluorite crystals are usually shaped like cubes, but when they are broken they become perfect octahedron, which have eight faces and are diamond-shaped (you can think of an octahedron as a shape that is like two Egyptian pyramids fused together at their bases) In rare cases fluorite has been found to have a botryoidal habit. If a mineral is described as having a botryoidal habit, it resembles a bunch of grapes. The word botryoidal was derived from the Greek word for “a bunch of grapes.”
As I said before, fluorite has many different uses. Its first use is a common one among colorful minerals: it is used as a gemstone. Since it is both soft and beautiful fluorite has been used to make carvings since ancient times. The ancient Egyptians used fluorite to make statues and scarabs and the people of China have used fluorite to make carvings for more than 300 years. Fluorite still has use as a gemstone today, but this use is limited due to fluorite’s softness. Sometimes fluorite cabochons are protected from scratching by coverings made of quartz crystal. Fluorite has also been used as a flux in the steel industry for a long time. A flux is a chemical that is put into a crucible along with metal or metal ores during the melting process to remove impurities from the metal. Fluorite makes a chemical reaction with some of the impurities in iron during the melting process to form slag. The slag can easily be skimmed off of the surface of molten iron and therefore removed easily. Fluorite has been used as a flux for many years and is still used today. The next use of fluorite is, in my opinion, the most interesting. Minerals are nothing more than pure chemical substances that have common crystal structures and fluorite is no exception. Fluorite’s chemical name is calcium fluoride, which is a common ingredient in fluoride toothpastes! If you check the ingredient lists on the tubes of many fluoride toothpastes, I am sure that you will soon come across one that lists calcium fluoride as its main active ingredient. That is why I said that you might have ingested fluorite and not even known it!
The name fluorite comes from the Latin word fluere, which means flowing, referring to the fact that fluorite can be melted easily. Fluorine, a gaseous chemical element, was named for fluorite since the gas was first discovered in fluorite. This brings up an important point: never treat fluorite with acid, if you do it will often release fluorine gas, which is highly poisonous!
Fluorite can be found in many places such as: Canada, the United States, South Africa, Peru, Thailand, Mexico, China, Eastern Europe, Norway, and the former Czechoslovakia. England is the main source of the “blue john” variety of fluorite.
By now you can probably see that fluorite is a very useful mineral. It has been used as a gem, a flux, and even as an ingredient in toothpaste. Fluorite has such a simple chemical makeup that it was easy for scientists to isolate and discover the element fluorine just by treating the stone with acid. Fluorite is also a good example of God’s handiwork, showing that even the things that God makes for less glamorous purposes, He still likes to make into marvelous shapes and dazzling colors.
Like many minerals fluorite can have many colors. Fluorite can be yellow, purple, green, clear, or blue. Like tourmaline, single fluorite specimens can display more than one color, but unlike tourmaline which does so in an orderly fashion, when fluorite displays different colors it is usually banded and has many layers of alternating colors. When fluorite forms as a banded mixture of blue and yellow it is called “blue john.” Fluorite crystals are usually shaped like cubes, but when they are broken they become perfect octahedron, which have eight faces and are diamond-shaped (you can think of an octahedron as a shape that is like two Egyptian pyramids fused together at their bases) In rare cases fluorite has been found to have a botryoidal habit. If a mineral is described as having a botryoidal habit, it resembles a bunch of grapes. The word botryoidal was derived from the Greek word for “a bunch of grapes.”
As I said before, fluorite has many different uses. Its first use is a common one among colorful minerals: it is used as a gemstone. Since it is both soft and beautiful fluorite has been used to make carvings since ancient times. The ancient Egyptians used fluorite to make statues and scarabs and the people of China have used fluorite to make carvings for more than 300 years. Fluorite still has use as a gemstone today, but this use is limited due to fluorite’s softness. Sometimes fluorite cabochons are protected from scratching by coverings made of quartz crystal. Fluorite has also been used as a flux in the steel industry for a long time. A flux is a chemical that is put into a crucible along with metal or metal ores during the melting process to remove impurities from the metal. Fluorite makes a chemical reaction with some of the impurities in iron during the melting process to form slag. The slag can easily be skimmed off of the surface of molten iron and therefore removed easily. Fluorite has been used as a flux for many years and is still used today. The next use of fluorite is, in my opinion, the most interesting. Minerals are nothing more than pure chemical substances that have common crystal structures and fluorite is no exception. Fluorite’s chemical name is calcium fluoride, which is a common ingredient in fluoride toothpastes! If you check the ingredient lists on the tubes of many fluoride toothpastes, I am sure that you will soon come across one that lists calcium fluoride as its main active ingredient. That is why I said that you might have ingested fluorite and not even known it!
The name fluorite comes from the Latin word fluere, which means flowing, referring to the fact that fluorite can be melted easily. Fluorine, a gaseous chemical element, was named for fluorite since the gas was first discovered in fluorite. This brings up an important point: never treat fluorite with acid, if you do it will often release fluorine gas, which is highly poisonous!
Fluorite can be found in many places such as: Canada, the United States, South Africa, Peru, Thailand, Mexico, China, Eastern Europe, Norway, and the former Czechoslovakia. England is the main source of the “blue john” variety of fluorite.
By now you can probably see that fluorite is a very useful mineral. It has been used as a gem, a flux, and even as an ingredient in toothpaste. Fluorite has such a simple chemical makeup that it was easy for scientists to isolate and discover the element fluorine just by treating the stone with acid. Fluorite is also a good example of God’s handiwork, showing that even the things that God makes for less glamorous purposes, He still likes to make into marvelous shapes and dazzling colors.
Monday, November 1, 2010
Pyrite the Impostor
Pyrite, or iron pyrite, as it is sometimes called, is a heavy mineral that has a metallic lustre. Its chemical name is iron sulfide, which means that it is composed of iron and sulfur. Pyrite is usually a brassy yellow color, but weathering can cause pyrite to display red, purple, orange, and blue colors. Pyrites that exhibit all of these colors are often called "rainbow pyrites" because the layers of color remind people of a rainbow. Pyrite is famous for growing in cube-shaped crystals, but can also grow in "suns" where its crystals radiate outward from a single point to form a circular pattern of long, tapering, triangular crystals that look like sunbursts. Pyrite crystals can also from in strange geometric shapes that have been given the name "pyriohedra." These shapes have twelve pentagonal, or five-sided, faces. Pyrite cubes can be smaller than the head of a pin or larger than an American quarter. Small cubes are often found as crusts on other rocks or bunched together in massive lumps. Pyrite can also replace organic materials to make fossils in a process known as pyratizing. Pyratized ammonites are the most famous example of pyrite fossils, but others ar common as well. I have found pyratized crinoid stems and brachiopods.
I'm sure a lot of people have heard the term "fool's gold" before. There are a few minerals that have been given this name, but the most common is undoubtedly pyrite. This is because pyrite is yellow in color, like gold. This is why I call pyrite the Impostor, because it is often mistaken for gold. However pyrite can be distinguished from gold by two simple methods. The first way to distinguish pyrite from gold is by the streak test. The streak test is a method used in mineral identification in which one scrapes the mineral in question against a piece of unglazed white porcelin leaving a streak. Each mineral has its own streak color, some streaks are a different color than the mineral that made them. Pyrite is yellow, but it has a green or black streak. Gold has a yellow streak. That test can easily determine whether or not a specimen is gold or pyrite. The second test is one that I have personally developed (I'm not sure if anyone else has done it before, but I don't think that I've ever seen it in a rocks and minerals book) I call it the rust test. Pyrite contains a great amount of iron in its composition and it will rust if it is exposed to too much water so, if you have a specimen that you think might be either gold or pyrite try dropping apiece of it in some water an allow it to sit for a while. It will usually rust after some time if it is in fact pyrite. A word of warning: the pyrite will most likely be ruined in this test!
Pyrite has had varied uses over the years. When struck with a iron, pyrite will sometimes produce sparks. This is actually where pyrite's name originated. The name pyrite comes from the Greek word pyr, which means fire, referring to the sparks. Because of its tendency to spark it was once used as a component in a firearm. The wheelock gun had a iron wheel that would turn and rub against a piece of pyrite inside the firearm and ignite the powder when one pulled the trigger. I read that you can produce sparks from pyrite by striking it with flint. I have tried this and haven't had any luck so far. Pyrite has been used to make jewelry since ancient times and is still used a little today; all though it is quite brittle and must be cut very carefully. It is not very valuable as a gemstone so it's usually only used to make costume jewelry. In fact pyrite has more use in industry than in most other fields today. Because of its high iron content pyrite is used as an iron ore. Pyrite can also be used to make sulfuric acid because of its sulfur content. Unfortunately in some places where pyrite was mined for use in these industries, too much pyrite power was allowed into the environment and some natural chemical weathering produced some sulfuric acid, which made its way into the areas' water and damaged some of the local wildlife. Fine pyrite crystals are also sold to collectors.
Pyrite is found all over the world in igneous, sedimentary, and metamorphic rocks. Some of the most obvious sources would be areas that are rich in sulfur and iron, like my home. I have found a few cubic crystals, two or three massive conglomerations of tiny cubes, and one crust. Areas around Detroit, Michigan, and Toledo, Ohio are also good localities in the USA in where pyrite can be found. On a rock-collecting trip that my church took to a location in Ohio near Toledo one rock hound found a conglomeration of cubes in which a lot of cubes protruded the specimen and were individually visible. Places where some of the best crystals can be found include, Spain, Peru, Italy, France, Mexico, and Italy. Because of its color, geometrically-shaped crystals, and history as "fool's gold' pyrite is truly an awesome mineral. I'm glad that our Creator has put it in so many places around the earth!
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