Wurtzite

Wurtzite, a dimorph of sphalerite, occurs in many sizes and habits at Gyöngyösoroszi in the Mátra Mountains of Hungary, and specimens this is a terrific example.  Formed within a binding matrix of snowy-white Calcite, the specimen surfaces are densely packed with steely-black, bright metallic tapering hexagonal Wurtzite crystals up to around 1.3 cm in length. About 50% of the crystals are perfectly terminated with a flat pinacoid.  A super example of Wurtzite from Gyöngyösoroszi.