Chamosite

Chamosite
A 3.6 by 2.2 cm of Axinite-Fe covered on both sides by greenish microcrystals of Chamosite
General
Category	Phyllosilicate
Formula (repeating unit)	(Fe2+,Mg)5Al(AlSi3O10)(OH)8
IMA symbol	Chm[1]
Strunz classification	9.EC.55
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	C2/m
Unit cell	a = 5.37 Å, b = 9.3 Å, c = 14.22 Å; β = 97.88°; Z = 2
Identification
Color	Green, grey-green, black
Mohs scale hardness	3
References	[2][3][4]

Chamosite is the Fe²⁺end member of the chlorite group. A hydrous aluminium silicate of iron, which is produced in an environment of low-to-moderate-grade metamorphosed iron deposits, as gray or black crystals in oolitic iron ore. Like other chlorites, it is a product of the hydrothermal alteration of pyroxenes, amphiboles and biotite in igneous rock. The composition of chlorite is often related to that of the original igneous mineral, so that more Fe-rich chlorites are commonly found as replacements of the Fe-rich ferromagnesian minerals (Deer et al., 1992).