Hisingerite

Hisingerite
Crystallized plates of reddish-brown, silver metallic-lustre hisingerite crystals
General
Category	Silicate mineral
Formula (repeating unit)	FeIII2Si2O5(OH)4 · 2 H2O
IMA symbol	Hsg[1]
Strunz classification	9.ED.10
Crystal system	Monoclinic Unknown space group
Unit cell	a = 5.4, b = 9.03 c = 14.99 [Å]; β = 98.32°; Z = 4
Identification
Color	Black, brownish-black
Crystal habit	Massive, compact; acicular, may be minutely spherical.
Cleavage	None
Fracture	Conchoidal
Tenacity	Brittle
Mohs scale hardness	2.5 - 3.0
Luster	Vitreous, resinous, greasy
Streak	Yellowish brown, green
Diaphaneity	Transparent to translucent
Specific gravity	2.43 - 2.67
Optical properties	Biaxial (-)
Refractive index	nα = 1.715 nγ = 1.730
Birefringence	δ = 0.015
References	[2][3][4]

Hisingerite is an iron(III) phyllosilicate mineral with formula Fe^III₂Si₂O₅(OH)₄ · 2 H₂O. A black or dark brown, lustrous secondary mineral, it is formed by the weathering or hydrothermal alteration of other iron silicate and sulfide minerals.^[2]

It was first described in 1751 by A.F. Cronstedt from Väster Silvberg, Dalarna, Sweden (under the name “kolspeglande järnmalm”), and in 1810 by W. Hisinger from the Gillinge iron mine, Södermanland, Sweden (“svart stenart”, later “gillingit”).^[5] In 1828 it was found at an occurrence in Riddarhyttan, Vastmanland, Sweden. It was named after Wilhelm Hisinger (1766–1852), a Swedish chemist.^[4]

There are also aluminian hisingerite variety in which one of the iron atoms is replaced by aluminium and chrome-alumina-hisingerite variety in which chromium substitutes for iron.^[3]

References

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This page was last edited on 28 August 2023, at 03:17