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Illinois State Mineral
Flourite
(CaF2)
Adopted in 1965.
Flourite was adopted in 1965 as the Illinois State Mineral. Fluorite is the natural crystalline form of calcium fluoride (CaF2). It is a transparent to transluscent, glassy mineral. When pure, fluorite is colorless; however, it usually contains impurities that color it. The most common colors are violet, blue, green, yellow, brown, pink, and blue-black; a single crystal may have bands of several colors. Fluorite often forms beautiful cube-shaped crystals.
Illinois is the largest producer of Fluorite in the United States. It is a soft stone often used in carved figurines and beaded jewelry. It also has many commercial uses as in making steel, aluminum, glass, and many chemicals
The most important fluorite deposits in the United States are found at Rosiclare and Cave-in-Rock, southern Illinois. At Rosiclare fluorite occurs as veins in the limestone bedrock. Some of these veins are as much as 12 meters (40 ft.) wide. Because of these deposits, Illinois is the largest producer of fluorite in the United States.
The deposits in Illinois were formed as hot water flowed up into the limestones of the area from deeper in the earth. Mineral deposits formed in this manner are called hydrothermal deposits. The hot water flowed up along weak areas in the rocks of this area. These weak areas are associated with the faults of the Wabash and Reelfoot rift zones. These two rift zones are also responsible for earthquakes such as the famous series of quakes at New Madrid, Missouri. The southern Illinois fluorite deposits were probably formed between 100 and 250 million years ago.
Fluorite is an important industrial mineral. The most common use is as a flux in producing steel. Another important use is in making hydrofluoric acid, which is used in the pottery, optics, and plastics industry. Fluorite is also used in making opalescent glass and in enameling cookware.
The name fluorite comes from the Latin fluere which means "to flow." This name comes from the fact that fluorite melts easily.
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50 State Resource Guide
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Everyone needs a little help, advice, or inspiration now and again. Find state colleges, universities, headline news, newspapers, debt consolidation, financial offerings, radios and TV stations, traffic reports, and state symbols: animals, birds,
flags, flowers, seals, and more as well as quick links to social, demographic, and economic statistics.
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