Blue stone is a generic mineral escription commonly applied to a variety of minerals. Perhaps the most common reference is to the hydrated copper(II) sulfate mineral, chalcanthite. The name "blue stone" is also applicable to lazurite, the core comstituent of lapis lazuli, a sulfide of sodium aluminium silicate in the sodalite group. The term bluestone is also used for the dolerite stones at Stonehenge.