STIBNITE  , a

mineral consisting of antimony sulphide, Sb2S3, 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 (rrXart,60aXµov); 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 . Antimonite is a name in common use for this species . The crystals are prismatic in habit, deeply furrowed longitudinally, and usually terminated by acute pyramidal planes . There is a perfect cleavage (ono) parallel to the length of the crystals, and the basal plane (oor) 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 a 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, &c., in metalliferous veins . Magnificent groups of brilliant crystals, up to 20 in. in length, are abundant in the extensive antimony mine of Ichinokawa, province of Iyo, Japan . Large, but dull, crystals have also been found at Lubilhac in Haute-Loire, France . Prismatic and acicular crystals often penetrating tabular crystals of barytes, are common at Felsobanya near Magy-Bknya and Kremnitz in Hungary .

(L . J .