It got its name from its color, which is the result of natural radiation. It is the brownish, greyish variety of quartz crystals. The totally dark, black crystals are called morions. Sometimes artifically radiated quartz or rock crystals are sold as smoky quartz. Its crystals usually turn up in volcanic, metamorphic or sometimes in sedimentary rocks. Huge crystals were found in the Alps during the construction of tunnels, its nice groups of crystals still can be found today in the alpine crevices. It also has other locations in Russia, Brazil, China etc.