A very rich and well formed Silver sulphide specimen with a mass of Stephanite crystals, many showing the six sided habit that looks a lot like Polybasite. Fine luster and a nice contrast with the slender Quartz prisms some of which are doubly terminated. The Stephanites are in remarkable condition for such an obviously old specimen of this delicate mineral. Especially impressive under magnification. The St Andreasburg mines are some of the greatest historical Silver mines in the world. The Harz mountains were already being worked in the middle ages, even in the 10th century, while St Andreasburg began in the 1600 era and became a major site, with very deep workings. Between 1910 and 1930 most all the mines were finished, we have sonly such specimens to reflect on this era.
A really large, pure Stephanite specimen that shows complex crystal faces on every side. In exceptional condition, besides being large this has a brilliant bright Silver luster. Stephanite is one of more rare Silver minerals and is soft (2-2.5) brittle and so not usually seen in such fine condition.
An older Fresnillo specimen this locality only rarely produced any specimens larger than thumbnails, and for that matter this is a large piece from anyplace. The intergrown sections of crystals are still very sharp with well defined striations and what seems to be many twin planes. A fine addition for a serious Silver suite or Mexican mineral collection.