Smoky quartz is a grey, translucent variety of quartz
that ranges in clarity from almost complete transparency to an almost-opaque brownish-grey or black crystal. The smoky colour results from free silicon formed from the silicon dioxide by natural irradiation.
Morion is the German, Danish, Spanish and Polish synonym for smoky quartz. Cairngorm is a variety of smoky quartz found in the Cairngorm Mountains of Scotland. It usually has a smoky yellow-brown colour, though some specimens are greyish-brown. The largest known Cairngorm crystal is a 23.6 kg (52 lb) specimen kept at Braemar Castle.