The green gemmy variety of the mineral spodumene. Other varieties are the pink kunzite and the rarely cut colourless to light yellow triphane.

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Hiddenit Hiddenite Korgal, Laghman, AfghanistanHiddenit Pech Valley, Kunar province, Afghanistan

Origin of name: after American explorer and geologist William Earl Hidden [1853-1918] who discovered the mineral in Alexander County, North Carolina, while prospecting for platinum on behalf of Thomas Alva Edison in 1879. When he also discovered emerald in the vicinity, Hidden founded a company to exploit and market both minerals.

Hidden was an ardent mineral collector and within only a few years he compiled an impressive mineral collection. In fact it was the second largest in the US at the time, after the Clarence S. Bement-Collection, which later went to the American Museum of Natural History in New York.

Today the Hidden-Collection is an important part of the mineralogical collection of Austrias Museum of Natural History in Vienna.
Why Hidden´s collection, or at least essential parts of it, were sold to the Imperial Royal Court Museum, as it was called back then, is rather a mystery. Records of the museum show that the Hidden collection was bought in 1888 for the stately sum of 15.000 guilders (roughly € 153 000) with the aid of an advance from the "All highest Family Fund" of the Imperial Household.  

Synonyms and trade names: none

Can be confused with: other green gems like beryl, chrysoberyl, peridot, verdelite (green tourmaline), green garnet (light coloured tsavorite, demantoid and grossular garnet), prasiolite etc.

Localities: Afghanistan, Brazil, China, Finland, Madagascar, Sri Lanka and the USA

Handling: hiddenite cleaves perfectly and is very sensitive to pressure. Moreover it is sensitive to heat and must be unset before soldering. Never clean ultrasonically! Sensitive to fluoric acid. Temperatures of 150°C and more may lead to colour changes.

Worth knowing: there is green spodumene which is photosensitive and fades upon prolonged exposure to light. This material must not be sold as hiddenite.

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Gemmological Properties of Hiddenite

Crystal system:
Mohs hardness:
Specific gravity:
3.15 to 3.21
Refractive index:
1.657 to 1.681
Max. Birefringence:
0.014 to 0.016
distinctly trichroic, yellow green - green - blue green
very weak, salmon pink to orange red
brittle, uneven
from greenish yellow to emerald green