Babingtonite Article

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Babingtonite
Babingtonite - Newington.jpg
General
Category Inosilicate
Formula
(repeating unit)
Ca2( Fe, Mn)Fe Si5 O14(O H)
Strunz classification9.DK.05
Crystal system Triclinic
Crystal classPinacoidal (1)
(same H-M symbol)
Space groupP1
Identification
ColorDark green to black
Crystal habitPrismatic crystals
CleavagePerfect on {001}, Good on {010} and {100}
FractureIrregular/uneven
TenacityBrittle
Mohs scale hardness5.5 to 6
LusterVitreous
DiaphaneityTranslucent on thin edges, opaque
Specific gravity3.3
Refractive indexnα= 1.700 nβ= 1.710 nγ= 1.725
Birefringenceδ = 0.025
PleochroismVisible
Dispersionr > v strong
References [1]

Babingtonite is a calcium iron manganese inosilicate mineral with the formula Ca2( Fe, Mn)Fe Si5 O14(O H). It is unusual in that iron(III) completely replaces the aluminium so typical of silicate minerals. It is a very dark green to black translucent (in thin crystals or splinters) mineral crystallizing in the triclinic system with typically radial short prismatic clusters and druzy coatings. It occurs with zeolite minerals in cavities in volcanic rocks. Babingtonite contains both iron(II) and iron(III) and shows weak magnetism. It has a Mohs hardness of 5.5 to 6 and a specific gravity of 3.3.

It was first described in 1824 from samples from Arendal, Aust-Agder, Norway (which is its type locality) and was named after the Irish physician and mineralogist William Babington (1757–1833). [2] [3]

It is the official mineral (mineral emblem) of the Commonwealth of Massachusetts. [4]

Image gallery

References