Calaverite

Calaverit is a rarely occurring mineral from the mineral class of " sulfides and sulfosalts " with the ratio of metal: tellurium < 1:1. It crystallizes in the monoclinic crystal system with the chemical composition AuTe2 and usually develops flaky or short prismatic crystals striped longitudinally, but also granular to massive aggregates of brassy yellow to silvery white color with metallic luster.

Special Features

Calaverit contains on average 56.4 % of tellurium, 43.6 % gold and 1% silver. It is dimorphic with Krennerit and closely related to sylvanite from which it can be distinguished only with difficulty.

Before the blowpipe Calaverit colors the flame blue green and it evolves white smoke. On coal produces a gold bead and the glass tube sublimates black tellurium and yellowish white tellurous acid.

Etymology and history

Calaverit was first found in 1868 by Frederick Augustus Genth in the Stanislaus mine in Calaveras County ( California ) in the United States and described by him. He named it after the type locality.

Classification

In the classification by Strunz Calaverit is classified in the sulfides and sulfosalts. It is counted among the sulfides with a ratio of metal to sulfur, selenium or tellurium of < 1:1 or 1:2. In the eighth edition, it made with Kostovit, Krennerit and sylvanite a group. In the ninth edition of the sulfides can be further divided by cations, where it forms Calaverite own sub- group of metal sulfides with a ratio of metal to sulfur, selenium or tellurium, of 1:2, and copper, silver, gold, nickel, tin, platinum group metals, molybdenum, or tungsten.

In the classification of minerals according to Dana it forms with Krennerit, sylvanite and Kostovit a subset of the sulfides - tellurides and selenides, including - with the composition AmBn Xp, with (m n): p = 1:2.

Education and Locations

Calaverit formed hydrothermally in gold-bearing courses. Accompanying minerals are Altait, Coloradoite, Krennerit and other Telluride.

Locations include Catamarca in Argentina; Kotayk Armenia; New South Wales, Queensland, Tasmania and Western Australia in Australia; La Paz in Bolivia; Oblast Pazardzhik in Bulgaria; Coquimbo in Chile; different regions in the People's Republic of China; Kirkland Lake / Ontario and Quebec in Canada; Salzburg in Austria; Bohemia in the Czech Republic; the island of Viti Levu Fiji group; Southern and Eastern Finland; Honshu in Japan; Eastern Siberia and the Urals in Russia; Andalusia in Spain; and Mother Lode / California, Cripple Creek / Colorado and many other regions in the United States.

Crystal structure

According to the classical mineralogy Calaverit crystallizes in the monoclinic crystal system, space group C2 / m with lattice parameters a = 8.76 Å; b = 4.41 Å; c = 10.15 Å; β = 125.2 °, and four formula units per unit cell .. However 1931 was discovered, can be described that his crystal faces not with integers according to the law of rational indices of René -Just Haiiy (see also Miller indices ). Calverit it one of the aperiodic crystals.

Use

Calaverit is a minor ore for the extraction of gold.