Spodumene
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| Spodumene | |
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| Image needed! | |
| General | |
| Category | Mineral |
| Chemical formula | lithium aluminium silicate, LiAl(SiO3)2 |
| Identification | |
| Colour | Highly variable: white, colorless, gray, pink, lilac, violet, yellow and green |
| Crystal habit | prismatic, generally flattened and elongated |
| Crystal system | monoclinic; 2/m |
| Cleavage | Perfect prismatic, two directions at nearly 90° |
| Fracture | Sub-conchoidal |
| Mohs Scale hardness | 6.5 - 7 |
| Luster | Vitreous |
| Refractive index | 1.66-1.68 |
| Pleochroism | Strong in kunzite: pink, colourless; hiddenite: yellow-green, blue-green |
| Streak | white |
| Specific gravity | 3.17-3.19 |
| Fusibility | 3.5 |
| Solubility | insoluble |
| Other | Tenebrescence, chatoyancy, kunzite often fluorescent under UV |
Spodumene is a pyroxene mineral consisting of lithium aluminium inosilicate - LiAl(SiO3)2 - and is a source of lithium. It occurs as colourless to yellowish, purplish or lilac kunzite (see below), yellowish-green or emerald-green hiddenite (see below), prismatic crystals, often of great size. Single crystals over 10 m in size are reported from the Black Hills of South Dakota.
Crystals form in the monoclinic system and are typically heavily striated parallel to the principal axis. Crystal faces are often etched and pitted with triangular markings.
Spodumene is derived from the Greek, meaning "burnt to ashes," owing to the opaque, ash-grey appearance of material refined for use in industry.
Spodumene occurs in lithium rich granites and pegmatites. Transparent material has long been used as a gemstone with varieties kunzite and hiddenite noted for their strong pleochroism. Source localities include Brazil, Madagascar, USA (North Carolina, California), Afghanistan, and Pakistan.
Kunzite
Kunzite is a hard pink gemstone, a variety of spodumene with the colour coming from manganese. It was named after George Frederick Kunz, who discovered it in Connecticut, USA in 1902. It is currently mined in Brazil, USA, Canada, CIS, Mexico and Sweden.
Hiddenite
Hiddenite is a green variety of spodumene first discovered at the Rist-Ellis mine in Hiddenite, North Carolina, USA. It, like kunzite is sometimes used as a gemstone.
References
- Webster, R. (2000). Gems: Their sources, descriptions and identification (5th ed.), pp. 186-190. Great Britain: Butterworth-Heinemann.
- Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0471805807
- Mineral Galleries (http://mineral.galleries.com/minerals/silicate/spodumen/spodumen.htm)
- Webmineral (http://webmineral.com/data/Spodumene.shtml)
- Mindat.org (http://www.mindat.org/min-3733.html)
See also: List of mineralsde:Kunzit pl:Spodumen