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 | |
| Category | Inosilicates |
| Formula (repeating unit) | Na(NaCa)Mg5Si8O22(OH)2# |
| IMA symbol | Rct[1] |
| Strunz classification | 9.DE.20 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | C2/m |
| Identification | |
| Color | Brown, yellow, red, or green |
| Crystal habit | Prismatic; acicular or asbestiform |
| Twinning | Simple or multiple parallel to {100} |
| Cleavage | Perfect |
| Fracture | Uneven, brittle |
| Mohs scale hardness | 5–6 |
| Luster | Vitreous |
| Streak | Pale yellow |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 3.0–3.5 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.615 nβ = 1.629 nγ = 1.636 |
| Birefringence | δ = 0.021 |
| Pleochroism | Strong: pale yellow, orange, and red |
| 2V angle | 68° measured |
| References | [2][3][4][5] |
References
edit- ^ 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.
- ^ "Handbook of Mineralogy" (PDF). Archived from the original (PDF) on 2015-09-24. Retrieved 2014-05-11.
- ^ Richterite on Mindat.org
- ^ Richterite data on Webmin
- ^ "IMA Master List". Archived from the original on 2015-01-05. Retrieved 2014-05-12.
- Bonewitz, 2008, Smithsonian Rock and Gem