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!