Mineral Information and Data:

Argyrodite
Ag8GeS6 [CNMNC approved formula]

Named from the Greek for "silver-containing.".

IMA status : Valid species (Pre-IMA 1886) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
02.05.06.01  
  (02) Sulfides - Including Selenides and Tellurides
  (02.05) where Am Bn Xp, with (m+n):p=3:2
  (02.05.06) Argyrodite Group
  
Nickel-Strunz
(10th edition) :
02.BA.35
  (02) Sulfides
  (02.B) Metal Sulfides, M:S > 1:1 (mainly 2:1)
  (02.BA) With Cu, Ag, Au
  
Crystal system: Orthorhombic System
Point group (H-M): mm2 — pyramidal
Unit cell: a = 15.15 Å, b = 7.48 Å, c = 10.59 Å
Crystal Habit: Crystals octahedral, dodecahedral; crystal aggregates, botryoidal crusts, massive
Twinning: Pseudospinel law {111}; repeated interpenetration twins of pseudododecahedra on {111}.
  
Color: Steel-gray with reddish tint, tarnishes black with blue tint
Diaphaneity: Opaque
Luster: Metallic
Hardness (Mohs): 2.5 - 3
Measured Density: 6.29 g/cm3
Tenacity: Brittle
Fracture: Uneven to slightly conchoidal
Streak: Grayish black
  
Polymorphism and Series: Forms a series with canfieldite.
Geologic Setting: In low-temperature polymetallic deposits with silver sulfosalts (Freiberg, Germany); in high-temperature Sn–Ag deposits (Bolivia).
Mineral Association: Canfieldite, stephanite, acanthite, pyrargyrite, polybasite, aramayoite, diaphorite, marcasite, pyrite, galena, sphalerite, cassiterite, siderite
  

 

Argyrodite
Origin: Veta Galufa, Colquechaca, Potosi Dept., Bolivia
Sample size: Microscopic image
Photo and Owner: Lou Perloff

 

Argyrodite
A large pocket filled with tetrahedrite crystals to 2 mm with a few areas showing dull grey argyrodite crystals to 0.5 - 0.75 mm.
Origin: Freiberg, Saxony, Germany
Sample size: 6.5 x 3 x 3 cm
Photo: Tom Loomis

 

Argyrodite
(zoom-in of above)

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