Another truly unusual and periscope-like specimen, consisting of a hollow tube of Mottramite cast after some now-missing mineral, and coated with translucent, disc-shaped rhombohedral calcite crystals. It looks just like a periscope, even more so than the last piece! Only very minor damage to this delicate and near-pristine, 360-degree specimen! 8 x 4.5 x 3.5 cm