Quartz is the component of a huge variety of rock types, and comes in an extensive range of colors and varieties such as agate and jasper.
Ancient Japanese believed quartz formed from the breath of a white dragon, and regarded it as representing perfection. Australian Aborigines used quartz in rain rituals. Crystals skulls were reportedly made by Atlanteans and are believed by some to be living entities. Clear quartz formed into spheres have been used as crystal balls to predict the future at least since the middle ages.
Quartz is often found in geodes and can be mined all over the world, most notably in Brazil and Arkansas, USA.