Unless you have been to Antarctica or know someone who has, this is a rarely available mineral species and specimen. This is a euhedral, tannish-gray anorthoclase feldspar crystal from Mt. Erebus, on Ross Island. This flattened, floater crystal is pristine. Mt. Erebus Volcano (3794m) is home to the world's only persistently convecting anorthoclase-phonolite lava lake. There is only one other place on the planet where these crystals can be found, Mt. Kenya, Africa. Crystals grow in the magma beneath Erebus and get spit out of the mountain inside glassy volcanic bombs. The glass quickly weathers away leaving the mountainside covered in crystals. These crystals are coveted by almost everyone at McMurdo Station. Links to this information were kindly provided by a geologist/neighbor of mine, who spent several field seasons mapping there. This was obtained in a small collection of a geologist, some years ago.