Calderite

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calderite
Dark red hexoctahedral crystals on light colored rock
Calderite crystals on matrix from Sunndal Norway
General
Category Silicate mineral
Formula
(repeating unit)
(Mn2+Ca)3(Fe3+Al)2(SiO4)3
Strunz classification 8/A.08–40
Dana classification 51.4.3a.6
Crystal symmetry Isometric - hexoctahedral (4/m 3 2/m)
Unit cell a = 11.819; Z = 8
Identification
Color brownish red to brownish yellow
Crystal system Cubic
Cleavage None
Mohs scale hardness 6.5-7.5
Luster Vitreous
Streak white
Diaphaneity transparent to translucent
Specific gravity 3.756
Optical properties Isotropic
Refractive index n = 1.872
References [1][2]

Calderite is a mineral in the garnet group with the chemical formula (Mn2+, Ca)3(Fe3+, Al)2(SiO4)3.

It is dark reddish brown to dark yellowish in color and generally granular massive in form.[3]

It was named for geologist James Calder who worked on the geology of India. The name was first applied to a rock in manganese deposits in Katkamsandi, Hazaribagh district, Bihar and at Netra, Balaghat district, Madhya Pradesh, India. later transferred to its predominant mineral.[2][3] In 1909 it was described as a mineral from Otjosondu, Otjozondjupa Region, Namibia.[1]

See also[edit]

  • James Calder, J. D. Herbert (1981). Geology of the Indian Sub-continent: Observations on Mineralogy, Cypsum, Mines and Mountain Formations (reprint ed.). Cosmo Publications. p. 218. 

References[edit]