Luis also offered about 20 superb thumbnails which are probably the world's best-yet specimens of the rare sulfosalt pearceite--the arsenic analog of polybasite
which, like that more common species, is apt to form platy, metallic black crystals grouped in rosette-shaped aggregates.
Pyrargyrite stockwork in siderite and quartz-encrusted cavities, together with acanthite, native silver, barite, kaolinite, and museum-quality specimens of polybasite
and stephanite were noted (Jeff Franzen and Ken Watson, pers.
The principal minerals which are found either banded or disseminated within the 90% quartz matrix include pyargyrite, ancanthite, proustite, polybasite
, miargiarite, galena, sphalerite, pyrite, and arsenopyrite.
The zones in 3 B are approximately the same in width and grade as the levels above (D 6) showing good continuity of the massive sulfides zones of polybasite
In the first decade of the 20th century, the Las Chispas mine near Arizpe in Sonora produced some of Mexico's largest and best specimens of polybasite
crystals, large clusters of "poker chip" stephanite crystals, fine acanthite crystal clusters and a few very fine pyrargyrite specimens.
24, 1998--On August the 21st the company reported, "There are now two distinct bands near the left wall and near the center that have over 80% sulphides (90% polybasite
with 10% chalcopyrite as inclusions) each of these is at least 10cm in width.
In recent years the Fresnillo area has produced remarkable examples of the silver sulfosalts pyrargyrite, stephanite and polybasite
There are now two distinct bands near the left wall and near the center that has over 80 percent sulphides (90 percent polybasite
with 10 percent chalcopyrite as inclusions) each of these bands is at least 10 cm in width.
The history of Guanajuato can be traced to a group of Spanish mule skinners who found silver there in 1548, Mining began in 1558 at the San Juan de Rayas mine, which since then has produced large numbers of superb specimens of acanthite, polybasite
and other silver minerals.
The Crown Crescent lode in the Emperor mine has yielded very minor amounts of bournonite, pyrargyrite, proustite and polybasite
In the central portion the predominate sulphide is polybasite
with some chalcopyrite as inclusions.
It is the latter polytype of the As-dominant species pearceite which forms a series with the much commoner Sb-dominant polybasite