quartz

noun2

1. •
   The most abundant mineral on the earth's surface, of chemical composition silicon dioxide, SiO₂. It occurs in a variety of forms, both crystalline and amorphous. Found in every environment.

   • Subsequently, the old Malay brought him the present specimen in a state of torpidity, telling him he had found it in a cavity of the quartz reef. — 1892
2. •
   (slang) Crystal meth: methamphetamine hydrochloride.