Bournonite(redirected from Endellionite)
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(named for the French mineralogist J. L. Bournon, 1751-1825), a mineral of the complex sulfide group. Its chemical composition is CuPbSbS3, with occasional admixtures of iron (to 5 percent) and silver (to 3 percent). Bournonite crystallizes in a rhomboidal system, forming thick columnar crystals or complex wheel-shaped twins. The color ranges from steely gray to iron black. Its hardness on the mineralogical scale is 3.0-3.5, and its density is 5, 800-5, 900 kg/m3. It associates with tetrahedrite, pyrite, chalcopyrite, galenite, and sphalerite in complex forms of cupric polymetallic hydrothermal deposits. Upon weathering, bournonite forms cerussite, malachite, and antimonic ochers. Deposits of bournonite occur in the USSR (Middle Asia, Transbaikalia, and other areas). Abroad, there are deposits in Australia and some South American countries (Chile, Peru, and Bolivia). Bournonite is used to obtain lead and copper.