A superb twinned crystal of Ferberite from the renowned Tasna mine in southern Bolivia. The piece was mined at the beginning of 2008, which is encouraging because I have seen very little in the way of Ferberites from this mine in recent years. This piece features the classic, "butterfly" twinning of Ferberite along the a (100) face. It is a good quality, sharp, lustrous, aesthetic jet-black twinned crystal with associated botryoidal Marcasite and small acicular crystals of grey Jamesonite. It has an attractive thick blocky form, and is a wonderful miniature size specimen. Twinned crystals from Bolivia are becoming increasingly difficult to obtain in recent years as the price of Tungsten ore has driven the miners to throw nearly all the Ferberite into the crusher, causing thousands of specimens to be lost forever.