Bournonite


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bournonite

[′bür·nə‚nīt]
(mineralogy)
PbCuSbS3 Steel-gray to black orthorhombic crystals; mined as an ore of copper, lead, and antimony. Also known as berthonite; cogwheel ore.

Bournonite

 

(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.

References in periodicals archive ?
Bournonite contains lead, copper, and antimony but has no silver values.
At Pierre Clavel's stand, the French bournonites (just mentioned), though nice enough, were upstaged by about 200 specimens of very sharp, lustrous, chocolate-brown to yellow-brown rhombohedral crystals of siderite to 10 cm, associated with thin-prismatic, transparent and colorless, crystals of quartz of similar size.
A few scattered rhodochrosites were also on hand, but otherwise it was the same mix of nice Chinese minerals and poor Chinese minerals that we've seen for the last several years: fluorite, stibnite, orpiment, quartz, calcite, broken bournonite, etc.
Some rare crystals are transparent; others are blue, dark blue, gray or nearly black because of abundant fine inclusions of bournonite or boulangerite.
Beautiful crystals of chalcopyrite are rather rare in the deposit, despite the production of 2,000 tonnes/year of copper concentrates at Trepca (copper in the ore is contained in chalcopyrite, pyrrhotite, tetrahedrite, tennantite, bournonite, bornite and enargite).
Luis reports that the great and renowned Herja mine near Baia Marie, Maramures, finally closed in December 2006, after who knows how many decades of yielding superb specimens of semseyite, stibnite, sphalerite, bournonite, fizelyite and other sulfides common and rare, as well as fine calcite, gypsum and quartz.
5-cm cubes of purple/yellow fluorite showing prominent phantoms, on a quartz druse (this specimen is about a foot wide), and, my own favorite specimen, probably, in all the show, a bournonite from the famed Herodsfoot mine, Cornwall, with a gleaming 3.
A final note: The Herodsfoot bournonite was a stunning-enough classic to see, but while Rob was setting up that showcase he took time out to remove from his pocket a small box and revealed the contents to those standing about: a mind-blowing, breath-taking phosphophyllite twin over an inch tall, the finest for its size that any of us (including Bill Larson, who has seen a lot
1-cm bournonite crystal with pyrite and sphalerite, and a sphalerite on bournonite, both in the Ben DeWit collection.
Since the Soviet collapse of the early 1990's the mines of Dalnegorsk have produced world-class specimens of an amazing number of major mineral species, but bournonite has not been one of them: Grant and Wilson (2001) report bournonite crystals to 1 cm from the Nikolaevsky mine (see vol.
Bandy (1944) mentioned small gray grains of bournonite.