Mineral Information and Data:

Argentojarosite
AgFe3+3(SO4)2(OH)6 [CNMNC approved formula]

Named in 1923 for the silver content and relationship to jarosite.

IMA status : Redefined IMA Approved; 2003 ()
CLASSIFICATION 
Dana
(8th edition) :
30.02.05.05  
  (30) Anhydrous Sulfates Containing Hydroxyl or Halogen
  (30.02) where (A B)2 XO4 Zq
  (30.02.05) Alunite Group (Jarosite Subgroup)
  
Nickel-Strunz
(10th edition) :
07.BC.10
  (07) Sulfates (selenates, tellurates, chromates, molybdates, wolframates)
  (07.B) Sulfates (selenates, etc.) with Additional Anions, without H2O
  (07.BC) With medium-sized and large cations
  
Crystal system: Trigonal System
Point group (H-M): 3m — ditrigonal-pyramidal
Unit cell: a = 7.35 Ǻ, c = 16.58 Å
Crystal Habit: Crystals microscopic; micaceous; flattened with hexagonal outline; fine-grained masses and coatings
  
Color: Yellow to brown
Diaphaneity: Transparent to translucent
Luster: Brilliant
Hardness (Mohs): 3.5 - 4.5
Measured Density: 3.62 to 3.66 g/cm3
Cleavage: 1; {0001}
Tenacity: Brittle
Fracture: Uneven to conchoidal
Streak: Yellow
  
Geologic Setting: An uncommon secondary mineral in the oxidized portions of silver- and sulfide-bearing mineral deposits.
Mineral Association: Anglesite, barite, quartz (Tintic Standard mine, Utah, USA)
  

 

Argentojarosite
Yellow crystalline massive argentojarosite.
Origin: Eagle Mine, Juab County, Utah, USA.
Photo: Jeff Weissman

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