Mineral Information and Data:

Chalcosiderite
CuFe3+6(PO4)4(OH)8 • 4H2O [CNMNC approved formula]

Named from the Greek for copper and iron, for those elements in the mineral’s composition.

IMA status : Valid species (Pre-IMA 1814) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
42.09.03.04  
  (42) Hydrated Phosphates Containing Hydroxyl or Halogen
  (42.09) where (A)3 (XO4)2 Zq · x(H2O)
  (42.09.03) Turquoise Group
  
Nickel-Strunz
(10th edition) :
08.DD.15
  (08) Phosphates, Arsenates, Vanadates
  (08.D) Phosphates, etc
  (08.DD) With only medium-sized cations, (OH, etc.):RO4= 2:1
  
Crystal system: Triclinic System
Point group (H-M): 1 — pinacoidal
Space group: P1
Unit cell: a =7.653(4)Å, b = 7.873(4) Å, c = 10.19Å α = 67.57(2)°, β = 69.17(2)°, γ = 64.93(2)° , Z=1
Crystal Habit: Crystals short prismatic, with a number of forms noted, typically in sheafs, to 3 mm; in crusts.
  
Color: Pale siskin-green to dark green
Diaphaneity: Transparent
Luster: Vitreous
Hardness (Mohs): 4.5
Measured Density: 3.22 g/cm3
Cleavage: One, perfect; another, less perfect
Streak: White to greenish, pale green
  
Polymorphism and Series: Forms a series with turquoise.
Geologic Setting: A rare mineral in the oxidized zone of some hydrothermal mineral deposits
Mineral Association: Dufrenite, goethite (West Phoenix mine, Cornwall, England); dufrenite, cyrilovite, leucophosphite (Gunheath china clay pit, Cornwall, England); sampleite, libethenite, crandallite, cyrilovite, pseudomalachite, sal´eeite, torbernite, ulrichite (Lake Boga quarry, Australia).
  

 

Chalcosiderite
Origin: Wheal Phoenix, Cornwall, England
Sample size: 6 x 5 x 5 cm, crystals to 1 mm
Photo: Tom Loomis

 

Chalcosiderite
(zoom-in of above)

 

Chalcosiderite
Origin: Hail Valley mine, Cornwall, England
Sample size: 7 x 6 x 4 cm
Photo: Tom Loomis

 

Chalcosiderite
(zoom-in of above)

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