Thursday, May 21, 2009

Hackmanite

One of the stones on my wish list from Tucson this year was Hackmanite, however the only stones I saw were translucent at best - so imagine my surprise when Pala International posted this beauty for sale!


The May Gem News from Pala International reports that:

Hackmanite is a phenomenal variety of sodalite and a member of the feldspathoid group, hackmanite is mostly found in a translucent cabochon form. This month we feature a transparent faceted hackmanite from Afghanistan. This gem is near-flawless and exhibits all the unusual optical characteristics associated with hackmanite.

Hackmanite is known for its unique color-shift phenomenon when subjected to warm white light or daylight. The phenomenon is known as tenebrescence. Hackmanite will often increase in saturation when allowed to be “charged up” in daylight and sometimes shifts between lavender and magenta hues. Long-wave ultraviolet light also brings out an amazing fluorescence, as seen directly below; in this case we see a glowing orange/yellow hue. The distinctive color phenomena are derived from the sulphur component in hackmanite’s chemistry. Light can polymerize the sulphur into different-length molecules and ions that, in turn, have different colors. (Thanks to Dr. George R. Rossman for clarification of the color phenomena science. See this Caltech webpage for more on the sodalite group.)

This stone is the May Featured Stone: Lavender hackmanite from Afghanistan, 7.87 carats, 16.28 x 11.08 x 8.64 mm. Inventory #17382. (Photo: Mia Dixon)
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