Rheniite is the only known mineral with Rhenium as its primary metallic constituent and as such is a fascinating species. It occurs at a volcanic vent in this remote area of Russia, and scientists have to climb down into hot crevasses to find the stuff. That being said, it is usually pretty ugly and massive material in terms of specimen appeal on the macro level. THIS piece, brought to my attention by my friend Dmitriy Belakovskiy of the Fersman Museum, has rheniite draped liberally on one side of the specimen and actual hardened rock made from the bubbly lava on the other! This shows the origins of the material so well, compared to most rather chunky specimens. Even aside from the lava, it is a really rich specimen with LOTS of bright microcrystalline rheniite.