Ferberite (twin) (rare matrix specimen)

Item Description

This specimen hosts a pair of very good twinned crystals of Ferberite on matrix from the renowned Tasna mine in southern Bolivia. The piece was mined at the beginning of 2008. Ferberite was sometimes previously referred to as "Wolframite", which was supposed to be an intermediary species between Ferberite and Hubnerite, but has since been discredited. This piece features the classic, "butterfly" twinning of Ferberite along the a (100) face of the crystals. The largest twin is doubly-terminated and measures 4.5 cm long. The Ferberite crystals are good quailty, sharp, and well-formed with the classic jet-black exterior. As I mentioned, this is a MATRIX specimen, which is exceptionally rare for this mine as most of the Ferberites from Tasna are blown off matrix during blasting, due to the heavy nature of the crystals and their perfect cleavage. The matrix is composed of crystalline Arsenopyrite with a few Quartz crystals sprinkled in. The piece is in great shape, though one end of the large twin has some embedded Quartz and a bit of Marcasite, but still fine condition compared to the countless many I've seen that are barely recognizable as specimens. Twinned crystals from Bolivia are becoming increasingly difficult to obtain from Tasna, ESPECIALLY on matrix, and 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. These twins are definitely the most highly sought after crystal habit from this locality. This piece is one of the better Ferberite twins that I have offered in a while. Valued in the inventory at $1,200.