Mineral Species: Ferberite

Chemical Formula: FeWO4

Chemical Name: Iron Tungstate

Mineral Class: Tungstate

Mineral Notes: Ferberite belongs to the Wolframite series with another mineral, Huebnerite, which is the Manganese end member. Most Wolframite specimens fall within 20 - 80% range of the series and these are referred to as Wolframites, (Fe,Mn)WO4. Ferberite's iron content causes significant differences between itself and Hubnerite. Ferberite tends to be black, with a black streak, is opaque with a nearly submetallic luster, is denser, and has crystals with a different elongation. Huebnerite tends to be pale in colour, with a lighter streak, more transparent and less dense. Ferberite is the rarer member of the series. 

Description: Lustrous black Ferberite crystals on matrix. The reflective crystals are hard to photograph - but are superb under magnification. Very strong metallic luster.

Location: Nederland District, Boulder Co., Colorado, USA