Fine thumbnail from the ancient Chichibu mining district in Japan. There are two dominant Bournonite crystals in this specimen. One is highly striated, as are the smaller, intergrown crystals, and the striations appear to be early stages of the famous Bournonite 'cogwheel' habit. The other dominant crystal is smoother and more orthogonal. The luster is shiny metallic, and the color is a uniform steel-grey with flashes of blue iridescence. I can't imagine that there are many good thumbnails from this deposit, which was first mined 1300 years ago during the reign of Empress Genmei. ex Jean Hamel TN collection, through dealer Scott Williams.