(h) Plane-polarized reflected light photomicrograph showing aggregate of altaite, greenockite, and petzite
In Table II, the study of the mineral composition of the ores demonstrated that the finest gold of high purity is present, as well as gold and silver in form of telluride's Calaverite (Au[Te.sub.2]), Silvanite (Au Ag [Te.sub.4]), Petzite (AgAu[Te.sub.2]), Hessite (AgTe), Shtiutzite and Bolinskite (AgBi[Te.sub.2]).
The main concentrations of gold are found in native gold and Petzite, broadly distributed among tellurides, and in silver concentrates, mixed with native gold, Hessite, and Petzite.
At Cresson, calaverite crystallization overlaps but has primarily occurred after the crystallization of base-metal sulfide minerals, and in some cases it is replaced by petzite
, melonite and altaite (Saunders, 1988).
Harvard University provided six cases of their magnificent (mostly Burrage collection) gold specimens, as well as a few specimens scattered in other cases (petzite
Then, from Level 2 of the Rex mine, Boulder County, brilliant tin-white altaite, coloradoite, petzite
and hessite are intermixed with duller gray massive galena on gray-white miniature-size rock matrix.
A number of rare telluride minerals have also been available from the Fersman Museum, and include rich, nearly pure, massive black coloradoite specimens (sometimes to over 1 kg) associated with massive hessite, petzite
, and occasional calaverite from Kochbulak, Uzbekistan.