An incredibly rare locality piece, and significant for this reason; a large, single crystal of the tin oxide, Cassiterite, from the famous Mount Mica Quarry. The surface has a mirror-like black coating that finishes about 60% of the crystal like a second layer over an earlier core. This is a fine quality cassiterite anyhow, but an even more impressive specimen from this well-known mine for tourmaline. Pegmatite cassiterite in general should be considered quite rare and is seldom seen in any lustrous, sharp crystals.