plural -s
: a mineral SiO2 that is a silica, differs from quartz in its usually minute thin tabular orthorhombic forms of crystallization, and is found in cavities in trachyte and similar rocks (hardness 7, specific gravity 2.28–2.33)

Word History


German tridymit, from Greek tridymos threefold (irregular from tri- three + didymos twin) + German -it -ite; from its common occurrence in trillings

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Dictionary Entries Near tridymite

Cite this Entry

“Tridymite.” Dictionary, Merriam-Webster, Accessed 20 Apr. 2024.

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