Hard Crystal Often Found in Watches, Clocks
Puzzle 19 of Homeschooling Pack
Question
Hard Crystal Often Found in Watches, Clocks
Answer
QUARTZ
Word Meaning:
QUARTZ — (mineralogy) 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.
Definitions from Wiktionary.