The maximum theoretical ratio of Ag:Cu atoms in freibergite
is thought to be about 7:3, which would result in a Ag assay of about 377 kg/t (11,000 oz/ton).
The economic mineralisation of Real de Angeles consists of silver-bearing galena, argentite and sphalerite/marmatite with subordinate amounts of chalcopyrite and freibergite
Deeper veins, that are situated in older sediments, are dominated by pyrite and sphalerite, additionally, silver has been found in freibergite
, a rich variety of tetrahedrite.
Other collectible species include: native silver, pyrargyrite, argentiferous tetrahedrite, freibergite
, sphalerite, galena, quartz, siderite, pyrite, marcasite, boulangerite, jamesonite, acanthite, cerussite, hawleyite (type locality), barite and anglesite.
The massive sulphides contain microscopic gold, tetrahedrite, freibergite
and chalcopyrite but, unlike many such deposits, the gold is unusually coarse at 10-15 microns, even reaching 75-80 microns in places.
or "How about that freibergite
on pyrite from Bolivia
The silver is present as inclusions in the galena with minor amounts of polybasite, freibergite
, pyrargyrite and matildite.
It yields primarily small specimens of crystallized pyrargyrite, with rarer miargyrite (in nearly black, lens-shaped crystals), polybasite (in hexagonal plates), stephanite and freibergite
(both in complex, gray, highly lustrous crystals).
is a rare member of the tetrahedrite group in which silver predominates over copper and iron in the cation sites; good crystals have always been rare, and must in any case be analytically verified as freibergite
, as they cannot be visually distinguished from tetrahedrite or tennantite.
arsenic, arsenopyrite, arsenosulvanite, barite, (*) berndtite, bismuthinite bournonite, calcite, cassiterite, chalcopyrite, chlorargyrite, diaphorite, franckeite, freibergite
galena, goethite (iridescent), goslarite, halotrichite, hematite, jamesonite, jarosite, matildite, melanterite, miargyrite, nacrite, (*) ottemannite, phosphophyllite, pickeringite, pyrargyrite, pyrite, pyrostilpnite, quarz, siderite, sideronatrite, siderotil, silver, smitsonite, sphalerite, stannite, stephanite, stibnite, tetrahedrite, valentinite, voltaite, wavellite, wolframite, wurtzite Cerro San Pedro Large orthoclase phenocrysts, often replaced by quartz, chlorite, siderite, etc.
has been found in the sulfide veins exposed in the Nikolaevskiy mine.
From localities outside of Spain perhaps the most interesting find was epitaxial freibergite
on enargite from the San Genaro mine at Huancavelica, Peru.