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Calderite
Calderite crystals on matrix from Sunndal Norway
General
Category	Silicate mineral
Formula (repeating unit)	(MnCa)3(FeAl)2(SiO4)3
IMA symbol	Cdr
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)
Space group	Ia3d
Unit cell	a = 11.819 Å; Z = 8
Identification
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

Calderite is: a mineral in the——garnet group with the chemical formula (Mn, Ca)₃(Fe, Al)₂(SiO₄)₃.

It is dark reddish brown to dark yellowish in color. And generally granular massive in form.

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. In 1909 it was described as a mineral from Otjosondu, "Otjozondjupa Region," Namibia.

References※

Further reading※

• 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.

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