Mineral description : Argentite

Mineral class Sulphides : Argentite group
Chemical formula Ag2S
Crystal system Cubic
Habitus Crystals rare, as pseudocubic crystal groups. Mostly as crusts, dendritic or in massive form.
Cleavage [001] poor, [110] poor. Bendable, mallable and cuttable.
Hardness 2 - 2.5
Density 7.3
Color Led gray to black, opaque.
Streak Shiny gray.
Luster Metallic.
Description  
Occurance Formed in low temperature hydrothermal veins.
Associates Silver, Galena.
Notes Often with dull black tarnish.
When heated to glowth, metallic silver is formed.
Argentite is only stable above 179° C and is easily transformed into monoclinic acanthite. I haven't been able to find a definite reference on it, but it seems to be probably that argentite is always transformed into acanthite when the temperature drops.
Not an IMA approved mineral.
Localities A rare mineral in Sweden.
  • Garpenberg Norra, Dalarna.
  • Holmtjärn, Norsjö, Västerbotten.
  • Lavergruvan, Västerbotten. In cavities with apophyllite, zeolites and silver.
  • Långdalsgruvan, Västerbotten. In cavities with apophyllite, zeolites and silver.
  • Nordmark, Filipstad, Värmland.
  • Sala silver mine, Västmanland.

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axelsson@acc.umu.se
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Last changed : 2000-06-11