SPODUMENE
Class : Silicates
Subclass : Inosilicates
Crystal system : Monoclinic
Chemistry : LiAlSi2O6
Rarity : Uncommon
Spodumene is the pyroxene of sodium and lithium pegmatites (sodolithic pegmatites). It has two particularly rare gemstone varieties : very pale green hiddenite (linked to traces of chromium) and pale pink kunzite (linked to traces of manganese). It owes its name to the Greek spodios (ashy) in allusion to the color of the mineral when heated. The crystals are generally elongated and flattened prismatic, with striated faces parallel to the elongation, commonly twinned ; spodumene also occurs in compact cryptocrystalline masses. Of vitreous luster, with a perfect cleavage according to (110), its color is variable, white, grayish, greenish. The transparent gemmy varieties are lilac pink (kunzite variety) or much rarer green to emerald green (hiddenite variety). Spodumene is an important ore of lithium, a light metal that finds applications in the manufacture of lubricants, as a flux in the aluminum industry, in ceramics, batteries as well as air conditioning. Varieties of gems, pale pink kunzite and green hiddenite were used in jewelry.
Spodumene in the World
Hiddenite is much rarer, known almost only from the pegmatite veins of California (Pala) and Stony Point, near Hiddenite (South Carolina). Large crystals were also taken out of Malagasy pegmatites.
Spodumene in France
In France, spodumene is reported as microcrystals in the Gwernavalou quarry near Guingamp (Côtes-d'Armor).
Twinning
Spodumene commonly twins on (100).
Fakes and treatments
No false recorded for this mineral species. In contrast, gemmy varieties are commonly treated to produce yellow to green tints. Irradiation of spodumene produces an orange to yellow-greenish color, these colors have not been described in Nature to date. When a kunzite is irradiated it produces an unstable light green to intense green hue (picture on the right) which fades when exposed to sunlight or gentle heating. The establishment of the systematic irradiation of American mail to counter attacks using envelopes contaminated with anthrax after the attacks of September 11, 2001 led to the involuntary color change of many kunzites passing through the postal service.
Hardness : 6.5 to 7
Density : 3.1 to 3.2
Fracture : Irregular to sub-conchoidal
Trace : White
TP : Translucent to transparent
RI : 1.648 to 1.679
Birefringence : 0.014 to 0.018
Optical character : Biaxial +
Pleochroism : Strong
Fluorescence : Yellow to green
Solubility : Insoluble
Magnetism : None
Radioactivity : None