quartz

noun

Etymology: From German Quarz, from Middle High German (Central East German) quarz, twarc, from a West Slavic language [compare Polish twardy (“hard”), Czech tvrdý (“hard”)], from Proto-Slavic *tvьrdъ ultimately from Proto-Indo-European *twerH- (“to enclose, grab”).

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.

   “The telescope and collimator have each an object-glass consisting of a single lens of quartz 1½ inch diameter and a focal length of 18½ inches for the sodium yellow light, but not more than 16 inches for the highest rays measured.”

   “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.”

2. Crystal meth: methamphetamine hydrochloride.