Tellurium

gold

emmonsite

Formula: Te
Native element, selenium group
Specific gravity: 6.1 to 6.3
Hardness: 2 to 2½
Streak: Grey
Colour: Tin-white
Melting point: 449.51°C
Boiling point: 988°C
Abundance in the earth’s crust: 1 part per billion by weight, 0.2 parts per billion by moles, which makes it one of the rarest stable solid elements (Wiki).
Environments

Volcanic fumeroles
Hydrothermal environments

Tellurium is a hydrothermal vein mineral, which may be of both primary and secondary origin, and also a sublimate in volcanic fumaroles. Associated minerals include native gold, sylvanite, empressite, altaite, pyrite, galena, alabandite, baryte, quartz and carbonates (HOM).

At the Emperor mine, Vatukoula, Viti Levu, Fiji, tellurium occurs as a component of massive ore intimately mixed with sulphides, tellurides and gold, and also as fine crystals up to 4 cm long in quartz cavities (Minrec 39.4.300-301).

The type locality is the Mariahilf Mine, Faţa Băii, Zlatna, Alba, Romania.

At mines in the Cripple Creek mining district, Colorado, USA, tellurite in the oxidised zone with emmonsite and native gold (Minrec 36.2.181).

Common impurities: Se,Fe,Bi,S

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