Tridymite & Cristobalite (high temp Quartz Paramorphs) – Location: Thomas Range? Juab Co.? Utah. Small Cabinet (see photo for more details). Here we have a nice specimen of the quartz paramorphs (same formula but higher temperature form distinct species) tridymite and cristobalite. This specimen is from a relatively new discovery that was made by us (topazminer) in the Thomas Range? Juab Co.? Utah. The tridymite and cristobalite formed in a high temperature fumarolic vent in rhyolite. We have a ?matrix? of mammilary cristobalite that formed first (cristobalite forms at a higher temperature than tridymite) with an outer layer of slightly lower temperature tridymite crystals. Normally tridymite forms as very small microscopic crystals; however? these crystals are easily visible. The crystals are a bluish to bluish-grey to almost white color and form clustered rosette Trilling groups (twinning). Larger tridymite crystal specimens are practically non-existent (with rare exceptions).