Acanthite

sulphide

primary mineral

Formula: Ag2S sulphide
Specific gravity: 7.3
Hardness: 2
Streak: Black
Colour: Lead grey
Solubility: Acanthite is slightly soluble in hydrochloric acid and sulphuric acid.
Environments:

Hydrothermal environments

Acanthite is a primary silver mineral that occurs in epithermal (low temperature) hydrothermal silver ore veins. It may also be of secondary origin. At atmospheric pressure, acanthite is stable below 173°C. Above 173°C the structure changes to produce crystals of twinned acanthite, known as argentite. Argentite is unstable below 173°C, and if the temperature drops below this level it will change back to acanthite.

Common impurities: Se

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