Mineral Information and Data:

Melanterite
Fe2+SO4 • 7H2O [CNMNC approved formula]

Named from the Greek melanteria, a process used to retrieve copper.

IMA status : Valid species (Pre-IMA 1850) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
29.06.10.01  
  (29) Hydrated Acid and Sulfates
  (29.06) where A XO4 · x(H2O)
  (29.06.10) Melanterite Group (Heptahydrates, Monoclinic: P21/c)
  
Nickel-Strunz
(10th edition) :
07.CB.35
  (07) Sulfates (selenates, tellurates, chromates, molybdates, wolframates)
  (07.C) Sulfates (selenates, etc.) without Additional Anions, with H2O
  (07.CB) With only medium-sized cations
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Unit cell: a = 14.08 Å, b = 6.51 Å, c = 11.05 Å, β = 105.6°
Crystal Habit: Crystals equant to short prismatic, also thick tabular or octahedral; stalactitic; fibrous; or pulverulent aggregates
  
Color: Green, greenish blue, blue, white
Diaphaneity: Translucent, Opaque
Luster: Vitreous, Silky
Hardness (Mohs): 2
Measured Density: 1.90 g/cm3
Cleavage: 2; {001} perfect, {120} distinct
Tenacity: Brittle
Fracture: Conchoidal
  
Geologic Setting: A post-mine product of oxidation of pyrite and marcasite ores; rarely a volcanic sublimate.
Mineral Association: Pisanite, chalcanthite, epsomite, pickeringite, halotrichite, other sulfates
  
Synonyms/varieties: Calingastite (Zn-rich var.), Copperas, Pisanite (Cn-rich var.)
Other Properties: H2O Soluble. BioMineral.
Comments: Usually a yellowish-white after exposure to air and moisture.

 

Melanterite
Origin: Patagonia District, Arizona, U.S.A.
Sample size: 5 x 9.5 cm specimen. Deep greenish blue encrustation of melanterite.
Photo: John Veevaert, Trinity Mineral Co

 

Melanterite
(zoom-in of above)

 

Melanterite
(zoom-in of above)

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