Tridymite - Wikipedia
Tridymite is a high-temperature polymorph of silica and usually occurs as minute tabular white or colorless pseudo-hexagonal crystals, or scales, in cavities in felsic volcanic rocks. Its chemical formula is Si O 2 .
鳞石英 - 百度百科
鳞石英包括了三种变体：属 六方晶系 的高温鳞石英和中温鳞石英，以及属于 斜方晶系 的低温鳞石英。 一般所称鳞石英均指低温鳞石英。 晶体常具高温变体的六方片状或板状的假像。 无色或白色。 破璃光泽。 硬度6.5。 比重2.3。 产于酸性火山岩的牢洞中。 【化学组成】SiO2，成分中常含少量杂质，特别是Al、Na、K和Ca。 【物理性质】有高温变体与低温变体之分。 高温变体即β-鳞石英，属六方晶系。 低温变体即α-鳞石英，属斜方晶系。 两者的转变温度为117℃。 晶体呈假 …
Tridymite: Mineral information, data and localities. - mindat.org
Tridymite is a low pressure, mostly high-temperature-stable polymorph of silica that can also form or persist metastably at low temperatures.
The Mineral tridymite - The Mineral and Gemstone Kingdom
Tridymite is a valuable mineral to collectors. Specimens of this rare and distinctive mineral provide interest to hobbyists. Tridymite is also used in scientific study. Its crystals provide key information to how crystals form, and how they change over in different environment s.
Tridymite | Silica polymorph, High-temperature form, Hexagonal …
tridymite, silica mineral, the stable form of silica (silicon dioxide, SiO 2) at temperatures between 870° and 1,470° C (1,598° and 2,678° F); at lower temperatures it transforms to high-quartz, at higher to cristobalite. It has three modifications: high-tridymite, middle-tridymite, and low-tridymite.
Tridymite - an overview | ScienceDirect Topics
Tridymite and cristobalite are high-temperature, low-pressure polymorphs of silica, forming stably above 870 °C (tridymite) and 1470 °C (cristobalite). In addition, they can form metastably in some low-temperature environments (e.g., they often form during the devitrification of siliceous volcanic or synthetic glass).
Tridymite Mineral Data
From the Greek Tridymos - "triplex." Comments: Clear, pseudohexagonal crystals of tridymite on matrix. Location: Bellerberg quarry, Laacher See, Rhineland-Palatinate, Germany. Scale: Not Given. Colorless, White, Yellowish white, Gray. Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.
Tridymite
Tridymite, with characteristic twinning, associated with thin plates of hematite. The tridymite appears to be pale blue but is actually colorless: the color is due to weak opalescence from the myriad internal fractures. The matrix is dominated by fine-grained, pale brown topaz but is locally rich in pale pink beryl. © Tony Peterson
Formation of Tridymite and Evidence for a Hydrothermal History …
2020年12月11日 · In August 2015, the Curiosity Mars rover discovered tridymite, a high-temperature silica polymorph, in Gale crater. The existing model for its occurrence suggests erosion and detrital sedimentation from silicic volcanic rocks in the crater rim or central peak.
Tridymite - PubChem
Cristobalite, mostly from calcined diatomaceous earth, is used to manufacture water glass, abrasives, ceramics and enamels. Cristobalite is also used to purify oils. [ACGIH] Crystalline silica not bound to other minerals is free silica.
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