Huya Village, Mt. Xuebaoding, Sichuan Prov., China
A rare example of metallic kesterite, covered by a layer of greenish mushistonite. The kesterite is sulfide of copper, zinc, iron and tin, while the mushistonite is a hydroxide of the same metals.
Although known from other localities, this is pretty much the only location from which samples are obtainable, and there has been almost no new material for the last several years. Kesterite/ Mushistonite combinations were always among the rarest specimens to come from the locality, but with decreased production of even the once common species (aquamarine, cassiterite, scheelite) these have become even harder to obtain, at least as fresh specimens.
When these were first discovered in the 90's, they were marketed as a new species called "pandaite"-- subsequent testing however, proved them to be a combination of 2 already known species.