Three pieces of barite, the crested and bladed form at the left, “glass” barite in the center, and a small crystal at the right.
Barite occurs in abundance in the Jefferson-Washington counties district, which furnishes about 80% of Missouri production. Other production comes from near Houston, Texas county, and from the central district—Miller, Moniteau, Morgan, Cole counties, and adjacent territory. In the Jefferson-Washington counties district, it is dug from residual clay over dolomite and is run through washing and concentrating mills which remove the clay and lighter waste rock. Most of the central district production comes from old sinkhole deposits, the ore being also crushed, washed, and concentrated in preparation for shipment. Missouri barite which was produced during 1941 had a value of over $1,300,000 and constituted about 40% of the total United States productions.
Barite is used as a paint pigment and extender, as a flux, as a source of barium in the chemical industry, as a filler in rubber, paper, oil cloth, textiles, and leather, and as a heavy substance in oil well drilling mud. The largest single use is in the manufacture of lithopone paint.
Gypsum
Gypsum is a soft mineral which can be scratched easily with the finger or thumb-nail. It may be glassy or transparent, or may grade into an opaque white body, possibly stained by iron oxide, but it is always very soft. Of the three varieties of gypsum—selenite, alabaster, and satinspar—only the first two have been found in Missouri by the writer. The chemical composition of gypsum is CaSO₄·2H₂O.
Transparent, flexible variety of gypsum (selenite).
Fine-grained, white, opaque gypsum (alabaster).