Mineral Information and Data:

Bulachite
Al2AsO4(OH)3 • 3H2O [CNMNC approved formula]

Named for the locality: Neubulach, northern Black Forest, Germany.

IMA status : Approved Species 1983 (IMA1982-081)
CLASSIFICATION 
Dana
(8th edition) :
42.06.07.02  
  (42) Hydrated Phosphates Containing Hydroxyl or Halogen
  (42.06) where (AB)2 (XO4) Zq · x(H2O)
  (42.06.07) Senegalite Group
  
Nickel-Strunz
(10th edition) :
08.DE.15
  (08) Phosphates, Arsenates, Vanadates
  (08.D) Phosphates, etc
  (08.DE) With only medium-sized cations, (OH, etc.):RO4 = 3:1
  
Crystal system: Orthorhombic System
Point group (H-M): mmm (or 2/m 2/m 2/m) — dipyramidal
Space group: Pmnm,
Unit cell: a = 15.53Ǻ, b = 17.78Ǻ, c = 7.03Ǻ, Z=10
Crystal Habit: As flattened needles, in bundles and radial aggregates, to 0.75 mm, in crusts.
  
Color: White
Diaphaneity: Translucent
Luster: Satiny
Hardness (Mohs): ~ 2
Measured Density: 2.60(10) g/cm3
  
Geologic Setting: Initially found on two museum specimens collected on mine dumps.
Mineral Association: Arsenocrandallite, malachite, azurite, barian pharmacosiderite, goethite, quartz
  

 

Bulachite
Tufts and batches of white acicular crystals
with satin luster in iron oxide coated vugs.
Origin: Sa Malesa, Sarroch, Cagliari Province, Sardinia, Italy.
Photo: © RRUFF Project

 

Bulachite
(zoom-in of above)

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