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 Quartz has been used as a building stone in years past, but it has been replaced by brick and was never the most prominent building stone anyway.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!

Amethyst--the Tie-dyed Quartz

        Amethyst is a purple-colored variety of the mineral quartz. In pure form quartz (silicon dioxide) is colorless, but impurities can alter its color. The purple color of amethyst is thought to be the product of tiny amounts of iron impurities. Amethyst can also be dichroic, which means that its color can appear to change when it is viewed at different angles (certain inks, such as the one used on the American $20 bill, do this too) Amethyst often has tiny drops of liquid trapped within its crystal structure, as well. The technical term for anything that is trapped within a crystal is an inclusion. In the case of amethyst these liquid inclusions are often called "tiger stripes" because the look like the stripes on a tiger's fur. It is because of all of these color phenomena that I call it the "tie-dyed quartz."
      Like quartz amethyst often forms within natural gas pockets and geodes. Quartz is the most common mineral in the world and is found everywhere on earth, so amethyst could theoretically be found anywhere. However there are certain areas where the mineral is found in abundance, most notably Brazil and the Ukraine. I have personally never found any in nature, but I do have three clusters of amethyst and one geode that contains the purple mineral. I think that amethyst is a beautiful mineral because its color is so uncommon.