Blende

Blende (Ger. blenden, 'to dazzle'), a name given to a number of minerals composed chiefly of sulphur and of certain metals, all or almost all of splendid lustre, at least in fractures and the faces of crystals. It is also very often popularly applied more exclusively to one of these minerals, to which alone, perhaps, it originally belonged, Zinc Blende, Garnet Blende, or Sphalerite; also called, according to its chemical composition, Sulphide of Zinc. Among English miners it is known as Black Jack. It is abundant both in crystalline and in sedimentary rocks in many parts of the world, and is often associated with Galena (q.v.), or Lead-glance. It contains about 66 parts of zinc and 33 of sulphur, and is used as an ore of Zinc (q.v.); but the reduction of it is attended with difficulty, which much diminishes its value. It is usually brown or black, sometimes red, yellow, or green. It occurs both massive and crystallised in rhomboidal dodecahedrons, octahedrons, and tetrahedrons. Macles, or twin crystals, are remarkably common. It is very brittle; before the blowpipe it decrepitates violently, but only fuses on thin edges.—Manganese Blende is a rare mineral composed of sulphur and manganese.—Antimony Blende, or Red Antimony, is also a rare mineral composed of sulphur and antimony.—Ruby Blende is a name sometimes limited to Pyroglyrite or Red Silver (see SILVER, ORES OF), sometimes extended as a sort of generic term to include a number of other minerals composed of sulphur and metals, among which are Cinnabar, Realgar, and Orpiment (q.v.).