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 aggregate, 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-rich 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 Hieronymous Theodor Richter (1824–1898).

Richterite
Richterite. Wilberforce, Monmouth Township, Haliburton County, Ontario, Canada.
General
CategoryInosilicates
Formula
(repeating unit)
Na(NaCa)Mg5Si8O22(OH)2#
IMA symbolRct[1]
Strunz classification9.DE.20
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/m
Identification
ColorBrown, yellow, red, or green
Crystal habitPrismatic; acicular or asbestiform
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[2][3][4][5]

References

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  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ "Handbook of Mineralogy" (PDF). Archived from the original (PDF) on 2015-09-24. Retrieved 2014-05-11.
  3. ^ Richterite on Mindat.org
  4. ^ Richterite data on Webmin
  5. ^ "IMA Master List". Archived from the original on 2015-01-05. Retrieved 2014-05-12.
  • Bonewitz, 2008, Smithsonian Rock and Gem