Blende (Ger. Menden, to deceive), a common ore of zinc, so named because, while often resembling galena, it yielded no lead, and thus deceived the miners. Another name for it is sphalerite, from treacherous. When pure it is composed of sulphur 33, zinc 67= 100; but part of the zinc is often replaced by iron, and occasionally by cadmium. It sometimes occurs in brilliant tetrahedral crystals, also fibrous, radiated, and massive. Its lustre is resinous to adamantine; color brown, yellow, black, red, green - white or yellow when pure. The English miners call it blackjack. Blende is found in both crystalline and sedimentary rocks, usually associated with galena, also with barite, fluorite, siderite, and ores of silver. It abounds with the lead ore of Missouri, Wisconsin, Iowa, and Illinois, and' has been found in many other localities in the United States. Derbyshire, Cumberland, and Cornwall afford different varieties; also Transylvania, Hungary, the Hartz, Sahla in Sweden, and many Saxon localities. - Owing to the difficulty of working this class of ore, it was formerly allowed to accumulate about the mouths of mines, and was not economized for zinc. In modern times, with improved metallurgical processes, zinc is largely made from blende, both in Europe and the United States. Calamine is preferred, but where this cannot be had, the blende is no longer thrown away.
By oxidation blende sometimes changes to zinc vitriol, and in the Hartz much zinc is reclaimed in this way. In 1863 Professors Reich and Richter of Freiberg discovered a new metal associated with zinc in blende, to which they gave the name indium, from the blue lines it produced on the spectrum. - The word blende is used to designate sulphur ores in general; for example, copper blende, manganese blende, and silver blende are the sulphur compounds of those metals.