SC525 - Sphalerite

Well-formed black sphalerite crystals. Fluorescent bright orange under longwave UV light. I suppose the fluorescence is limited to a superficial layer due to the complete absence of fluorescence in a few broken crystals. The sphalerite is also triboluminescent: orange light is emitted when the sphalerite is scratched. At the base of the sphalerite there is a white-fluorescent mineral, likely calcite, with a few quartz crystals. On the back there is a mix of sphalerite, pyrite, calcite, and a few very small crystals fluorescing blue under shortwave UV light, possibly scheelite.