STIBNITE, a mineral consisting of antimony sulphide, occurring as bladed or acicular orthorhombic crystals; an important ore of antimony. It was mentioned by Dioscorides and Pliny under the names stimmi, stibi and platyophthalmon (rXarvipOaXp.ov) ; the last name refers to the use which the ancients made of the powdered mineral for darkening the eye brows to increase the apparent size of the eyes. The Arabic name al-kohl (now strangely corrupted to alcohol) had reference to the same use. Antimonite is also a common name for this species.
The crystals are prismatic in habit, deeply furrowed longi tudinally, and usually terminated by acute pyramidal planes. There is a perfect cleavage (oi 0) parallel to the length of the crystals, and the basal plane (ow ) is a plane of gliding; the latter gives rise to very characteristic transverse striations or nicks on the cleavage surfaces of crystals which have been bent.
The colour is lead-grey, and the lustre metallic and brilliant; crystals become dull on prolonged exposure to light. Cleavage flakes of extreme thinness transmit a small amount of red light, but are more transparent for heat rays. The mineral is quite soft (H=2), and has a specific gravity of 4.6. Stibnite occurs with quartz in beds and veins in gneisses and schists, or with blende, galena, etc., in metalliferous veins. Magnificent groups of bril liant crystals, up to 20 in. in length, were formerly abundant in the antimony mine of Ichinokawa, on Shikoku island, Japan. Large, but dull, crystals have also been found at Lubilhac in Haute-Loire, France. Prismatic and acicular crystals often pene trating tabular crystals of barytes, are common at Baia Sprie in Rumania (formerly FelsObanya, Hungary). (L. J. S.)