Fluorspar, or fluorite, is a glassy mineral that is commonly gray, white, or colorless, but may be green, blue, purple, yellow, or black. It is composed of calcium and fluorine. Fluorite is not a gem because it is too fragile and soft. Mineral collectors seek it because it is attractive and because some varieties have the ability to glow under invisible ultraviolet light (hence the term “fluorescence”). WHERE ARE FLUORSPAR DEPOSITS LOCATED AND HOW IMPORTANT IS ILLINOIS PRODUCTION? Fluorspar produced in the United States comes chiefly from a small area in Illinois and Kentucky where it has been mined since 1842. Illinois produced about 66 percent of the nation’s total in 1963. The state’s production amounted to more than 132,000 tons, valued at about $6,547,000. The crude ore is extracted from nearly horizontal bedded deposits and from nearly vertical veins in mines up to 800 feet deep in Pope and Hardin Counties. Finished fluorspar is produced from the crude ore by separating and concentrating methods. WHAT ARE FLUORSPAR PELLETS? In the separation of fluorspar from the other materials with which it naturally occurs, a process is used that involves grinding the spar to a very fine powder. The powdered spar has a number of uses, but to suit it for use as a flux (a substance which promotes fusion) it is made into pellets by the use of a binder. WHAT IS FLUORSPAR USED FOR? Fluorspar is used extensively as a flux in the steel industry, but over 50 percent of the spar produced in Illinois in 1963 was consumed in the manufacture of hydrofluoric acid. A large portion of this acid production is used in the aluminum industry. Hydrofluoric acid is also employed in the preparation of many fluorine compounds, particularly those used in the production of fluorocarbons (refrigerants, plastics, aerosols), insecticides, and high-energy fuels for rockets and missiles. The fluorocarbons utilize about 40 percent of the hydrofluoric acid production. LEAD AND ZINC WHAT ORES YIELD LEAD AND ZINC IN ILLINOIS? The mineral galena is the principal ore of lead. Galena is gray in color, very heavy, has a bright metallic luster, and breaks into cubes along steplike cleavage surfaces (fig. 18). It is composed of lead and sulfur. The chief ore of zinc is the mineral sphalerite. It may be brown, yellow, or black. Sphalerite is a combination of zinc and sulfur, has a resinous luster, and is not as heavy as galena. WHERE ARE LEAD AND ZINC MINES LOCATED AND HOW LONG HAVE THESE ORES BEEN MINED?