Melanterite
Melanterite | |
---|---|
Melanterite as found in nature. | |
General | |
Category | Sulfate mineral |
Formula (repeating unit) | FeSO4·7H2O |
Strunz classification | 07.CB.35 |
Dana classification | 29.06.10.01 |
Crystal system | Monoclinic |
Space group | Monoclinic 2/m prismatic |
Unit cell | a = 14.077 Å, b = 6.509 Å, c = 11.054 Å; β = 105.6°; Z = 4 |
Identification | |
Color | Green, pale green, greenish blue, bluish green, colorless |
Crystal habit | Encrustations and capillary efflorescences; rarely as equant pseudo-octahedral, prismatic or tabular crystals |
Cleavage | {001} Perfect, {110} Distinct |
Fracture | Conchoidal |
Mohs scale hardness | 2 |
Luster | Vitreous |
Streak | White |
Diaphaneity | Subtransparent to translucent |
Specific gravity | 1.89 - 1.9 |
Optical properties | Biaxial (+) |
Refractive index | nα = 1.470 - 1.471 nβ = 1.477 - 1.480 nγ = 1.486 |
References | [1][2][3] |
Melanterite is a mineral form of hydrous iron(II) sulfate: FeSO4·7H2O. It is the iron analogue of the copper sulfate chalcanthite. It alters to siderotil by loss of water. It is a secondary sulfate mineral which forms from the oxidation of primary sulfide minerals such as pyrite and marcasite in the near-surface environment. It often occurs as a post mine encrustation on old underground mine surfaces. It also occurs in coal and lignite seams exposed to humid air[1] and as a rare sublimate phase around volcanic fumaroles.[3] Associated minerals include pisanite, chalcanthite, epsomite, pickeringite, halotrichite and other sulfate minerals.[3]
It was first described in 1850.[3]
Gallery
-
Crystal structure of melanterite
-
Cuprian Melanterite
References
This article is issued from Wikipedia - version of the 12/2/2015. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.