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.
crystals to 4 mm are seen as floaters in the galena-calcite mixture.
First, Pierre Clavel (firstname.lastname@example.org) 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
Some rare crystals are transparent; others are blue, dark blue, gray or nearly black because of abundant fine inclusions of bournonite
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.