Dark red hexoctahedral crystals on light colored rock

Calderite crystals on matrix from Sunndal Norway
Category Silicate mineral
(repeating unit)
Strunz classification 9.AD.25 (10 ed)
8/A.08–40 (8 ed)
Dana classification 51.4.3a.6
Crystal system Cubic
Crystal class Hexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Unit cell a = 11.819 Å; Z = 8
Color brownish red to brownish yellow
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


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