common form of native silica or silicon dioxide, 1756, from German Quarz, Zwarc "rock crystal," from Middle High German twarc, probably from a West Slavic source, compare Czech tvrdy, Polish twardy "quartz," noun uses of an adjective meaning "hard," from Old Church Slavonic tvrudu "hard," from Proto-Slavic *tvrd-, from PIE *(s)twer- "to grasp, hold; hard."
word-forming element indicating origin or derivation from, from French -ite and directly from Latin -ita, from Greek -ites (fem. -itis), word-forming element making adjectives and nouns meaning "connected with or belonging to." Especially used in classical times to form ethnic and local designations (for example in Septuagint translations of Hebrew names in -i) and for names of gems and minerals.
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Harper, D. (n.d.). Etymology of quartzite. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/quartzite