Friday, June 8, 2012

Gemstone of the Week: Hübnerite

(Hübnerite image found on Wikipedia)

Hübnerite is a Manganese Iron Tungstate.  It was discovered by Adolf Hübner in 1865 and forms as crystals that may be prismatic, tabular, or flattened with striated faces.  Hübnerite also commonly forms as twinned cystals and most often occurs in granitic pegmatites and hydrothermal veins.  In colour, it is generally reddish-brown, but can be so dark as to appear almost black, and is often found with Quartz, Casserite, Topaz, and Lepidolite.  Hübnerite, which used to be known as Wolframite, is a major tungsten ore.  Some of the best specimens come for Peru and the state of Colorado.