Richterite

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Richterite
Richterite-mrz156a.jpg
Richterite. Wilberforce, Monmouth Township, Haliburton County, Ontario, Canada.
General
CategoryInosilicates
Formula
(repeating unit)
Na(NaCa)Mg5Si8O22(OH)2
Strunz classification09.DE.20
Identification
ColorBrown, yellow, red, or green
Crystal habitPrismatic; acicular or asbestiform
Crystal systemMonoclinic
TwinningSimple or multiple parallel to {100}
CleavagePerfect
FractureUneven, brittle
Mohs scale hardness5-6
LusterVitreous
StreakPale yellow
DiaphaneityTransparent to translucent
Specific gravity3.0-3.5
Optical propertiesBiaxial (-)
Refractive indexnα = 1.615 nβ = 1.629 nγ = 1.636
Birefringenceδ = 0.021
PleochroismStrong: pale yellow, orange, and red
2V angle68° measured
References[1][2][3][4]
 
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Richterite
Richterite-mrz156a.jpg
Richterite. Wilberforce, Monmouth Township, Haliburton County, Ontario, Canada.
General
CategoryInosilicates
Formula
(repeating unit)
Na(NaCa)Mg5Si8O22(OH)2
Strunz classification09.DE.20
Identification
ColorBrown, yellow, red, or green
Crystal habitPrismatic; acicular or asbestiform
Crystal systemMonoclinic
TwinningSimple or multiple parallel to {100}
CleavagePerfect
FractureUneven, brittle
Mohs scale hardness5-6
LusterVitreous
StreakPale yellow
DiaphaneityTransparent to translucent
Specific gravity3.0-3.5
Optical propertiesBiaxial (-)
Refractive indexnα = 1.615 nβ = 1.629 nγ = 1.636
Birefringenceδ = 0.021
PleochroismStrong: pale yellow, orange, and red
2V angle68° measured
References[1][2][3][4]

Richterite is a sodium calcium magnesium silicate mineral belonging to the amphibole group. If iron replaces the magnesium within the structure of the mineral, it is called ferrorichterite; if fluorine replaces the hydroxyl, it is called fluororichterite. Richterite crystals are long and prismatic, or prismatic to fibrous aggregates, or rock-bound crystals. Colors of richterite range from brown, grayish-brown, yellow, brownish- to rose-red, or pale to dark green. Richterite occurs in thermally metamorphosed limestones in contact metamorphic zones. It also occurs as a hydrothermal product in mafic igneous rocks, and in manganese-rish ore deposits. Localities include Mont-Saint-Hilaire, Quebec, and Wilberforce and Tory Hill, Ontario, Canada; Långban and Pajsberg, Sweden; West Kimberley, Western Australia; Sanka, Myanmar; and, in the US, at Iron Hill, Colorado; Leucite Hills, Wyoming; and Libby, Montana. The mineral was named in 1865 for the German mineralogist Theodore Richter (1824–1898).

References[edit]