Every gemstone species has its interesting quirks and spodumene is no exception. It is a major source of the rare element lithium, itself a fascinating metal. Lithium is the lightest of all metals and the least dense solid element known to man. Lithium has many important industrial applications, including heat-resistant glass and ceramics, mood-stabilizing drugs, aircraft alloys and lithium batteries.
Spodumene draws its unusual name from the Greek word, spodumenos, meaning ash-colored, in reference to the color of spodumene crystals that are not of gemstone quality. Gem-quality spodumene is rather more colorful, and includes colorless, yellow, pink, violet, yellowish-green and medium-deep green. However, this type of spodumene is very rare. The two best-known varieties - hiddenite and kunzite - were discovered only in the last 130 years.
By chemical composition, spodumene is lithium aluminum silicate with a hardness of 6.5 to 7 on the Mohs scale. It has a vitreous luster, excellent transparency and good brilliance; its refractive index (1.660 to 1.681) is just slightly less than that of tanzanite. Spodumene is moderately dense, with a specific gravity of 3.15 to 3.21. It has perfect cleavage, a property it shares with diamond and topaz. It also has very pronounced pleochroism, meaning that it displays different colors when viewed from different angles.
The yellow variety of spodumene is known simply as spodumene, while the green and pink varieties are known respectively as hiddenite and kunzite. A colorless variety has recently been discovered in Madagascar and a few very rare specimens of light-blue spodumene have been found in Afghanistan. While most of the world's supply of gem-quality spodumene comes from Afghanistan, Pakistan, Madagascar and Brazil, the first specimens of both hiddenite and kunzite were discovered in the USA.
Hiddenite was named after W.E. Hidden. Hidden was a mineralogist who was sent by Thomas Edison to North Carolina to look for platinum. He discovered hiddenite instead. The green variety of spodumene is colored by traces of chromium. In order to display strong colors, the table facets must be perpendicular to the main axis of the stone. The top and bottom of the crystal reveal the deepest colors and expert gem cutters take advantage of this.
Kunzite was first discovered in San Diego County, California in 1902 and named in honor of George Frederick Kunz, the legendary American gemologist. Kunzite ranges in color from pale-pink, violet or lilac to medium-pink. Kunzite is colored by traces of manganese. It is recommended that kunzite not be exposed to strong light since the delicate color is known to fade over time. For this reason kunzite is sometimes called the "evening" stone.
- First Published: February-18-2008
- Last Updated: October-03-2014
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