Smokey quartz is a dark variaiton of quartz, it is often transluscent and a shade of black or grey however, some specimens may be completely opaque and black. The colour is due to free silicon at the time the quartz was forming, formed from silicon dioxide from natural radiation. These particular mineral specimens are of massive smokey quartz, where the pieces have a highly crystalline texture that individual crystals can not be seen. They were collected by staff from Iveland, Norway and have a very dark grey colouration to them. Available in various sizes, the samples will come supplied in a card tray with an information label.