The top of this rhyolite matrix is scattered richly with colorless micro crystals of sharply formed tridymite. Small platy metallic crystals of hematite are scattered throughout. The specimen comes with a previous label from the collection of Jack Nieburger.Topaz Mountain in the Thomas Range of Utah consists of pale volcanic rhyolite formed during the Tertiary period through extensive lava flows and trapped gas cavities. Within these hollow lithophysae and vapor-phase cavities, high-temperature minerals like tridymite crystallized alongside topaz, bixbyite, and hematite. Historically, the region has been a premier public collecting destination and rockhounding landmark where amateur and professional collectors extract specimens from the porous rock and surrounding washes.
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