2 : SULFIDES and SULFOSALTS (sulfides, selenides,
tellurides; arsenides, antimonides, bismuthides; sulfarsenites,
sulfantimonites, sulfbismuthites, etc.)
G : Sulfarsenites, sulfantimonites, sulfbismuthites
A : Neso-sulfarsenites, etc. without additional S
Arsenic, Xanthoconite, Stephanite, Acanthite, Tetrahedrite,
is a rare member of the Proustite Group of minerals
that also includes Pyrargyrite.
Both minerals are ofter referred to by the nickname
"Ruby Silver" because of their deep red color
and silver content. Proustite is a silver arsenic sulfide
and Pyrargyrite is a silver antimony sulfide. The two
are isostructural which means the two minerals
have the same structure but a different chemistry. Proustite
is rarer than Pyrargyrite espessially when it comes
to faceted gems. Proustite gems are almost impossible
to find since crystals are usually too small or dark
and faceting is very difficult due to its softness.
Proustite gems can be very attractive with the deep
red color and adamantine luster.
as with other silver minerals, is reactive to light
and can form a white coating or turn black upon prolonged
exposure. The white coating can be wiped off, but the
blackening can't be reversed. Gems and specimens should
be stored in the dark with limited light exposure.
occurs at many localities, but rarely in fine crystals
or as an important ore mineral. From Germany, in the
Himmelsfürst mine, Erbisdorf, near Freiberg; and at
Niederschlema, Saxony. In Romania, at Sacarîmb (Nagyág).
From Jáchymov (Joachimsthal) and Príbram, Czech Republic.
At Sainte-Marie-aux-Mines, Haut-Rhin, France. From Sarrabus,
Sardinia, Italy. In the USA, in Colorado, at Red Mountain,
San Juan County, and at Georgetown, Clear Creek County;
in Idaho, large masses at the Poorman mine, Silver City
district, Owyhee County; in Nevada, in the Star mine,
Cherry Creek district, White Pine County In Canada,
from the Keeley mine, South Lorrain Township, Ontario.
In Chile, at Chañarcillo, south of Copiapó, Atacama,
as exceptional crystals. From Mexico, at Batopilas,
Chihuahua, and Sombrerete, Zacatecas.