Barite (“Tiff” in south_east_ Missouri, Heavy Spar, Barytes) occurs in
Missouri predominantly as a white, quite heavy, soft, non-metallic
mineral which has a high luster on a freshly broken surface. Slightly
bluish “glass” barite or “glass tiff” has been found in smaller quantity
with the more abundant, opaque white material. The glassy barite may
superficially resemble calcite or selenite gypsum, but in distinction,
barite breaks or cleaves to surfaces joining at right angles and does
not effervesce with acid, whereas calcite does effervesce in acid and
cleaves at oblique angles (rhombohedral cleavage). Gypsum is so soft
that it can be scratched very easily with the thumb-nail, whereas barite
is scratched with difficulty, if at all, by the thumb-nail. Notably,
again, barite is “heavy,” with a specific gravity of about 4.5, whereas
calcite, gypsum, limestone, and chert are “lighter,” with a specific
gravity of about 2.6 to 2.7. Barite has the composition barium sulphate,
BaSO₄, of which barium oxide constitutes 65.7 per cent.
[Illustration: 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.