Tridymite (triclinic polymorph of Quartz) (ex Kay Robertson Collection)

Item Description

Tridymite high-temperature, low-pressure polymorph of Quartz that is typically found as thin pseudo-hexagonal (triclinic) crystals in some igneous rocks and stony meteorites. Tridymite was first described in 1868 and the type location is in Hidalgo, Mexico. This piece features attractive small, sharp, lustrous, gemmy pseudo-hexagonal (triclinic) "star"-shaped twins of Tridymite measuring up to 2.5 mm with minor Cristobalite and Sanidine on Rhyolite matrix. Good quality for the species and the locality, and this is a great opportunity for a rare species collector ot pick up a hard to find piece of this sought after material. It should be noted that in December 2015, the team behind NASA's Mars Science Laboratory announced the discovery of large amounts of Tridymite popularly known as Mount Sharp, which is in the Marias Pass on the slope of Aeolis Mons on Mars. This discovery was certainly unexpected due to the rarity of the mineral here on Earth and the apparent lack of volcanic activity where it was discovered. At the time of discovery no explanation for how it was formed was available. Ex Kay Robertson Collection (#4293). Kay is a prominent California collector, who specialized in European classics (see the article in the March-April, 2007 Mineralogical Record and the 50+ page article in the German Magazine "Mineralien Welt" November-December 2017).