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 ?
Had all future feed stocks simply contained the customary tetrahedrite with some pyrite and the occasional elevated galena ([less than]3%), the plant could well have handled ore from the Sunshine mine without difficulties, but enter bournonite. As a copper mineral, it behaves like tetrahedrite in the flotation process.
The xenomorphic tetrahedrite and freibergite usually coexist with bournonite, boulangerite, jamesonite, chalcopyrite, and galena (Figures 4(n), 5(c), and 6).
The Crown Crescent lode in the Emperor mine has yielded very minor amounts of bournonite, pyrargyrite, proustite and polybasite.
First came three stunning new bournonite miniatures found in September 2007 at the renowned locality called Machacamarca: clean, lustrous, satiny gray "cogwheels," each about 5 cm across, are attached at high angles to form clusters devoid of matrix or associated species.
First, Pierre Clavel (minepro@wanadoo.fr) had good bournonite miniatures from the Mine des Malines, Gard, France.
Until recently the finest examples of bournonite were those found at the Herodsfoot mine in England over a hundred years ago.
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.
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.
Among the 14 large cabinet pieces here was a matrix plate of fluorite from the Rodderup Fell mine, Alston Moor, Cumbria, with gorgeous, glowing, 3.5-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 3.5-cm metallic black cogwheel rising from amidst others on a 12-cm matrix covered by drusy quartz.
4 and 11); the photos show a 2.1-cm bournonite crystal with pyrite and sphalerite, and a sphalerite on bournonite, both in the Ben DeWit collection.