A beautiful, relatively unknown tenebrescent gemstone.
If you are looking for a unique gemstone to add to your gem collection, then take a look at the very rare variety of Sodalite known as Hackmanite.
Discovered in 1896 in Greenland by a man called L.C. Boergstroem, this gem absorbs direct sunlight (ultraviolet light) which turns the gem from a pale, creamy colour to a stunning purplish violet colour. The phosphorescent effect on Hackmanite is different to that found in Kunzite. Whilst Kunzite will absorb the sun’s ultraviolet rays, and then glow in the dark for a short period, Hackmanite’s actual body colour will change under the same conditions and this change can last for a very long period. The absorption of light in some gemstones is known as phosphorescence, whereas the phenomenon which leads to an actual colour change is known as “tenebrescence”. The gem is translucent to opaque in appearance and at 5.5 – 6 on the Mohs hardness scale it’s best kept as a collectable or set into a pendant.
As far as I am aware, Hackmanite of this type has only ever been discovered in Afghanistan and Burma. However, it has been found in Canada and the USA where the gem actually changes colour in the opposite direction when exposed to ultra violet light!