- a polymorph of quartz occurring in the form of small crystals, commonly twinned, in siliceous volcanic rocks.
Origin of tridymite
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Examples from the Web for tridymite
The crystals, called cristobalite and tridymite, swim in clouds around stars just before they begin to form planets.Space Bling: From Diamond Planets to Crystal Oceans to Precious Moon Jewels
Alexa Valiente, Jaewon Kang
October 13, 2012
Spherulites may be regarded as radiate aggregates of such microliths (mostly felspar mixed with quartz or tridymite).
When crystalline grains or blebs of quartz occur, we have a quartz-trachyte; when tridymite is abundant, as in the trachyte of Co.Volcanoes: Past and Present