andradite
Sign in to savethumb|Andradite garnet – Jiangxi, Nantan, China. Andradite is a mineral species of the garnet group. It is a nesosilicate, with chemical formula Ca3Fe2Si3O12.
Key facts
- Mineral.name
- Andradite [Adr]
- Mineral.category
- Garnet group
- Mineral.image
- Andradite-Mali.jpg
- Mineral.imagesize
- 260px
- Mineral.caption
- Single crystal (4.2cm) – Diakon, Nioro du Sahel Circle, Kayes Region, Mali
- Mineral.formula
- Ca3Fe2(SiO4)3
- Mineral.IMAsymbol
- Adr
- Mineral.strunz
- 9.AD.25
- Mineral.system
- Cubic
- Mineral.class
- Hexoctahedral (mm) H-M symbol: (4/m 2/m)
- Mineral.symmetry
- Iad
- Mineral.unit cell
- a = 12.056 Å; Z = 8
- Mineral.color
- Yellow, greenish yellow to emerald-green, dark green; brown, brownish red, brownish yellow; grayish black, black; may be sectored
- Mineral.habit
- Commonly well-crystallized dodecahedra, trapezohedra, or combinations, also granular to massive
- Mineral.cleavage
- none
- Mineral.fracture
- conchoidal to uneven
- Mineral.tenacity
- Brittle
- Mineral.mohs
- 6.5 to 7
via Wikipedia infobox
Article
4 sectionsContents
- Occurrence
- See also
- References
- External links
thumb|Andradite garnet – Jiangxi, Nantan, China. Andradite is a mineral species of the garnet group. It is a nesosilicate, with chemical formula Ca3Fe2Si3O12.
Andradite includes four varieties: Colophonite: a historical variety found in the Scandinavian islands, brownish or reddish in color, often opaque or translucent. Demantoid: Vivid green in color, one of the most valuable and rare stones in the gemological world. Melanite: Black in color due to limited substitution of titanium for iron. Also known as "titanian andradite". Forms a solid solution with morimotoite and schorlomite depending on titanium and iron content. Topazolite: Yellow-green in color and sometimes of high enough quality to be cut into a faceted gemstone, it is rarer than demantoid.