Illinois once led the United States in the production of fluorite, our state mineral. The Gem in Your Toothpaste

Story By Rachel Mahan produced more fluorite than any other resces, or glows, under ultraviolet Photo By Adele Hodde state over the years it was mined here. light. In fact, fluorite lends its name to No wonder it was named the state min - this property. eral in 1965. While these characteristics make flu - llinois is unique for many familiar This attractive mineral, also known as orite seem like a gemstone, it rarely is reasons, but even natives may not fluorspar in the mining industry, comes used like one. realize that it is what lies under - in an array of colors. Described as trans - “It’s not commonly used because of ground that makes this state a real parent to translucent, it can be purple, its softness,” said Fifarek, who also is an diamond in the rough. blue, green, yellow, white and clear. economic geologist specializing in min - Southern Illinois is home to a The pure mineral, also called calcium eral deposits. “You really have to be “gem” found in your toothpaste, in fluoride, is made of calcium and fluorine careful with it.” tIhe manufacture of the steel for your and has no color. So fluorite’s rainbow On a hardness scale from one to 10, car, and in ceramics in your kitchen. palette comes from small amounts of where 10 is the hardness of a diamond, It’s called fluorite, other elements that take the place of fluorite is a four, he said. Sometimes, and, according calcium in the crystal structure. though, it is set in necklaces or to the Illi - The colors also may be due to tiny brooches or added to mineral collec - nois vacancies where an atom should be tors’ shelves. Miners used to chip the State found but isn’t, said Richard Fifarek, an crystals into octahedral “diamonds” Geolog - associate professor of geology at South - for display, according to ical ern Illinois University at Carbondale. the ISGS. Survey, The way light interacts with these In this area of the country, Illinois vacancies may cause color differences. fluorite occurs in a small por - Fluorite can be tion of southeastern Illinois banded and multicol - and western ored. Some even Kentucky fluo -

10 / Outdoor Illinois January 2010 called the Illinois-Kentucky Fluorspar fluorite deposits were found while dig - Kentucky Fluorspar District, partly Mining District. ging a well. At first, fluorite was merely because of uncertainty in obtaining It was here, millions of years ago, treated as a waste product. But in the fluorspar from foreign sources. that hot fluid containing fluorite and late 1800s it began to be used in the The legacy of the mining industry metals, such as zinc and lead, rose up making of steel. still remains: Fluorite enthusiasts can into cracks in the rock, cooled, and Today, the ISGS cites some of its visit the old office building that deposited veins of fluorspar, writes uses: smelting metal alloys, refining alu - belonged to the Rosiclare Lead and geologist Zakaria Lasemi in an article in minum and uranium, and use in optics, Fluorspar Mining Company. It is now the forthcoming “Geology of Illinois” lubricants, toothpastes and plastics. In home to The American Fluorite Muse - published by the Illinois State Geologi - the past it was used to make refriger - um and its specimens, photographs and cal Survey, Institute of National ants. However, the chloro-fluorocar - mining information. According to Lase - Resource Sustainability, University of bons in these refrigerants are believed mi, Rosiclare and nearby Cave-in-Rock Illinois. Veins, he writes, can be as thin to damage the ozone layer and are and Elizabethtown once were the as a feather or up to 30 feet wide. banned, said Fifarek. fluorspar mining “headquarters.” These veins are the dominant type In 1942, Illinois led the United States Wherever you are in Illinois or of formation, said Fifarek. But fluorspar in fluorite production, writes Lasemi, beyond, be sure to enjoy the many col - can also be found in “bedding who also studies and maps mineral ors of this mineral and its interesting deposits,” which run almost parallel to deposits for the ISGS. In the 1990s, history: underground millions of years the earth’s surface. Bedding deposits though, more and more fluorite was ago and at the end of your toothbrush formed when the rocks dissolved and coming from overseas, from places such today. fluorite took their place. as China or Mexico. Illinois became the An historical marker in Rosiclare in sole U.S. producer, but in 1995, the last Hardin County tells how fluorite was mine in the country shut down because Rachel Mahan is a freelance writer and native of southern Illinois. discovered in this it was too expensive to mine fluorspar mining district. In and because of the foreign competition, the mid-1800s, according to the ISGS. A transparent to transluscent Now, writes Lasemi, there is a possi - bility that mining may begin mineral, small amounts of other again in the elements in the crystal structure Illinois- are responsilbe for the rich diver- sity of colors found in fluorite.

January 2010 Outdoor Illinois / 11