- Tazna Mine (Tasna Mine; Tazna-Rosario Mine), Cerro Tazna, Atocha-Quechisla District, Nor Chichas Province, Potosi Department, Bolivia
- Thumbnail, 2.7 x 2.0 x 1.7 cm
Here is a superb twinned crystal of Ferberite. This piece features the classic, "butterfly" twinning of Ferberite along the (100) face. This piece is a superb quality, sharp, lustrous, aesthetic jet-black twinned crystal. This crystal shows a rather closed reentrant angle. It has a great thick blocky form, and is wonderful thumbnail of this rarely seen material. Twinned crystals from Bolivia have becoming increasingly difficult to obtain from Bolivia. These are definitely the most highly sought after crystal habit from this locality This piece one of the better formed Ferberite twins that I have seen from Bolivia. Ex. Brian Kosnar.