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 St.-Hilaire, Quebec, and Wilberforce and Tory Hill, Ontario, Canada; Langban 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.
Richterite | |
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File:Richterite.jpeg | |
General | |
Category | Silicate - inosilicates |
Formula (repeating unit) | Na(Ca, Na)Mg5Si8O22(OH)2 |
Crystal system | Monoclinic |
Identification | |
Color | Brown, yellow, red, or green |
Crystal habit | Prismatic |
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 |
See also
References
- Bonewitz, 2008, Smithsonian Rock and Gem