Arsenic

native element

hydrothermal

Formula: As
Native element, forms a series with antimony
Specific gravity: 5.6 to 5.8
Hardness: 3½
Streak: Tin-white
Colour: Tin-white, tarnishing to dark grey or black
Solubility: On heating arsenic sublimes without melting
Environments:

Hydrothermal environments

Arenic occurs in hydrothermal veins and deposits that contain other arsenic minerals, sometimes in cobalt-silver sulphide veins. (HOM) It oxidises slowly in air and is then covered with a thin crust of tiny arsenolite crystals.(Mindat) Associated minerals include arsenolite, cinnabar, realgar, orpiment, stibnite, galena, sphalerite, pyrite and baryte. (HOM)

At Llallagua, Bolivia, arsenic has been identified in a specimen consisting of alternating lamellae of native arsenic, realgar and gypsum, probably formed by the oxidation of arsenopyrite. (MinRec 37.2.126)

Common impurities: Bi,Sb,Fe,Ni,Ag,S,Se

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