Barite—barites, heavy-spar, barium sulphate; orthorhombic, H. 3–3.5; luster vitreous to resinous, sometimes pearly; white, inclining to yellow, gray, blue, red, or brown; very heavy, sp. sr. 4.3–4.7.
Biotite—black mica, a potash-aluminum-magnesium-iron silicate; monoclinic; easy basal cleavage into thin laminæ; sometimes occurs as a massive aggregation of cleavable scales; H. 2.5–3; luster splendent on cleavage surface; black to dark green; cleavage surfaces smooth and shining; a very common constituent of crystalline rocks.
Bitumen—the same as asphaltum (q.v.).
Bismuth—a metal of whitish color and rather brittle nature; occurring occasionally native, usually as an ore.
Bronzite—a variety of enstatite (q.v.); grayish green to olive-green and brown with luster on cleavage surface often adamantine, pearly or bronze-like and submetallic.
Calcite—calcspar; calcium carbonate; rhombohedral, perfect rhombohedral cleavage; often taking the forms known as dogtooth spar, nail-head spar; frequently stalactitic and stalagmitic; H. 2.5–3.5; luster vitreous; white, occasionally pale shades of gray, red, green, blue, violet, yellow, brown; strong double refraction; embraces variety called Iceland spar; a very common mineral; the essential basis of limestone.
Cassiterite—tin stone; an oxide of tin; tetragonal; luster adamantine, usually splendent; brown or black, sometimes red, gray, white, or yellow; an important source of tin.
Catlinite—essentially a hardened red clay, rather a rock than a mineral; much prized by Indians for pipes.
Chalcedony—a cryptocrystalline variety of quartz having a wax-like luster, either transparent or translucent; white, grayish, pale brown to dark brown, black, sometimes delicate blue, occasionally other shades; frequently occurs as the lining or filling of cavities, taking on a botryoidal or mamillary form.
Chiastolite—andalusite (q.v.).