The gemstones mined in Arizona are semi-precious and widely used in jewelry and other crafts such as intarsia. Turquoise is without a doubt the most common gemstone mined in Arizona but there are other stones also found in a part of the state that is called “The Valley of the Sun”, a region surrounding Phoenix where gemstone mining takes place in the mountains.(1) Other significant places in the state where gemstone have been mined include the Shannon Mountains of Greenlee County, which borders New Mexico. Here, azurite has been found along with turquoise and malachite. Peridot Mesa in San Carlos in the northwest Gila County contains large deposits of peridot, a bright yellow-green stone.(2)
The Four Peaks Mine near Phoenix contain amethyst(3) while the Blackstar Mines southwest of Tucson have had a unique variety of blue opal which is volcanic in origin.(4)
A list of gemstones and minerals mined in Arizona are(5):
Turquoise is made of aluminum and copper with the chemical formula written as: CuAl6(PO4)4(OH)8 .4H2O. Commonly used in southwestern jewelry, turquoise ranges from sky blue to shades of blue-green.
Peridot is made of magnesium, iron, and silicon with the chemical formula written as: (Mg,Fe)2SiO4.
This pretty yellow-green gemstone is sometimes called the “Poor Man’s Emerald” but it is significantly lighter in green than most emeralds.
Amethyst is made of silicon and is a type of quartz, with the chemical formula written as: SiO2. Found in abundance all over the nation, amethyst is a favorite semi-precious stone used in jewelry and ranges from lavender to deep purple in color.
Garnets are made of nesosilicates and they come in a variety of different types. Each type has a chemical formula written as: X3Y2(SiO4)3. The X usually has a Ca, Mg, or Fe in its place while the Y has a Al, Fe, or Cr in its place. Garnets range from deep red to a purple-red color.
Agate is a type of quartz usually classified as a microcrystalline form of calcedony. The chemical formula for agate is: SiO2. Agates are usually formed on old volcanoes and they come in a wide variety of colors, from pink to orange, green, red, purple, and brown. Most agates have a hollow center and beautiful bands of colors through the stone.
Jasper is an opaque silicate that is a form of chalcedony. What causes the different colors is the presence of a material or mineral oxide in the silicate. The chemical formula for jasper is written as: SiO2. The colors frequently make very unique and beautiful patterns in each stone.
Opals are a hydrated silica classified as a mineraloid gel due to presence of water trapped in the stone. Opals come in every color from white to blue, red, and black although white and blue opals are primarily found in Arizona. The chemical formula written for opals is: SiO2.H2O. The water inside of each opal provides a shimmer of iridescent rainbow color.
Azurite, like turquoise, also is found where copper mines exist. This beautiful opaque blue stone has the chemical formula of: Cu3(CO3)2(OH)2.
Malacite is a carbonate mineral that usually appears along with azurite and sometimes turquoise, also being a copper mineral. A green stone, the shades can range from evergreen to a sea foam green. The chemical formula for malachite is written as: Cu2CO3(OH)2.
Chalcedony is a cryptocrystalline variety of silica that contains quartz and moganite. Like agate, it comes in a wide variety of colors and can be translucent or semi-transparent. The chemical formula for chalcedony is written as: SiO2.
1. http://www.gemland.com/geohistory.htm.
2. http://www.gemland.com/gemology.htm.
3. Ibid.
4. http://www.blackstarmines.com/01home.html.
5. http://minerals.usgs.gov/minerals/pubs/commodity/gemstones/sp14-95/contents.html.
