Spodumene

:"Kunzite" redirects here. For the Sailor Moon character, see Shitennou."

Infobox mineral
name = Spodumene
category =
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caption = An almost colorless kunzite crystal (upper left), a cut pale pink kunzite (upper right) and a greenish hiddenite crystal (below) (unknown scale)
formula = lithium aluminium silicate, LiAl(SiO₃)₂
color = Highly variable: white, colorless, gray, pink, lilac, violet, yellow and green
habit = prismatic, generally flattened and elongated
system = monoclinic; 2/m
twinning =
cleavage = Perfect prismatic, two directions at nearly 90°
fracture = Sub-conchoidal
mohs = 6.5 - 7
luster = Vitreous
refractive = 1.66-1.68
opticalprop =
birefringence =
pleochroism = Strong in kunzite: pink, colorless; hiddenite: yellow-green, blue-green
streak = white
gravity = 3.17-3.19
melt =
fusibility = 3.5
diagnostic =
solubility = insoluble
diaphaneity =
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 colorless to yellowish, purplish or lilac kunzite (see below), yellowish-green or emerald-green hiddenite, prismatic crystals, often of great size. Single crystals of 14.3 m in size are reported from the Black Hills of South Dakota, United States. [Robert Louis Bonewitz, 2005, "Rock and Gem", London, Dorling Kindersley]

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 "spodumenos" (σποδυμενος), 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.

Economic importance

Spodumene is an important source of lithium for use in ceramics, mobile phone and automotive batteries, medicine and as a fluxing agent. Lithium is extracted from spodumene by fusing in acid.

World production of lithium via spodumene is around 80,000 metric tonnes per annum, primarily from the Greenbushes pegmatite of Western Australia, and some Chinese and Chilean sources. Spodumene is becoming less important a source of lithium due to the emergence of alkaline brine lake sources in China and Argentina, which produce lithium chloride directly. Lithium chloride is converted to lithium carbonate and lithium hydroxide by reaction with sodium carbonate and calcium hydroxide respectively.

Kunzite

Kunzite is a pink to lilac colored gemstone, a variety of spodumene with the color coming from minor to trace amounts of manganese. Some (but not all) kunzite used for gemstones has been heated to enhance its color. It is also frequently irradiated to enhance the color. Many kunzites fade when exposed to sunlight. It was discovered in 1902, and was named after George Frederick Kunz, Tiffany & Co's chief jeweler at the time, and a noted mineralogist. It has been found in Brazil, USA, Canada, CIS, Mexico, Sweden, Western Australia, Afghanistan and Pakistan.

References

* Anthony, John W., Bideaux, Richard A., Bladh, Kenneth W., and Nichols, Monte C. (1990): Handbook of Mineralogy: Mineral Data Publishing, Tucson, Arizona
* Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0-471-80580-7
* Kunz, George Frederick (1892) Gems and Precious Stones of North America. The Scientific Publishing Company, New York NY
* Palache, C., Davidson, S. C., and Goranson, E.A. (1930) The Hiddenite deposit in Alexander County, N.Carolina. American Mineralogist Vol 15 No. 8 p. 280
* Webster, R. (2000). "Gems: Their sources, descriptions and identification" (5th ed.), pp. 186-190. Great Britain: Butterworth-Heinemann.
* [http://webmineral.com/data/Spodumene.shtml Webmineral]
* [http://www.mindat.org/min-3733.html Mindat.org]

ee also

*List of minerals