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- Q641830 subject Q17462688.
- Q641830 subject Q6442973.
- Q641830 subject Q7282399.
- Q641830 abstract "Seifertite is a silicate mineral with the formula SiO2 and is one of the densest polymorphs of silica. It has only been found in Martian and lunar meteorites where it is presumably formed from either tridymite or cristobalite – other polymorphs of quartz – as a result of heating during the atmospheric re-entry and impact to the Earth, at an estimated minimum pressure of 35 GPa. It can also be produced in the laboratory by compressing cristobalite in a diamond anvil cell to pressures above 40 GPa. The mineral is named after Friedrich Seifert (born 1941), the founder of the Bayerisches Geoinstitut at University of Bayreuth, Germany, and is officially recognized by the International Mineralogical Association.Seifertite forms micrometre-sized crystalline lamellae embedded into a glassy SiO2 matrix. The lamellae are rather difficult to analyze as they vitrify within seconds under laser or electron beams used for standard Raman spectroscopy or electron beam microanalysis, respectively, even at much reduced beam intensities. Nevertheless, it was possible to verify that it is mainly composed of SiO2 with minor inclusions of Na2O (0.40 wt.%) and Al2O3 (1.14 wt.%). X-ray diffraction reveals that the mineral has scrutinyite (α-PbO2) type structure with an orthorhombic symmetry and Pbcn or Pb2n space group. Its lattice constants a = 4.097, b = 5.0462, c = 4.4946, Z = 4 correspond to the density of 4.294 g/cm3 which is among the highest among any forms of silica (cf. density of quartz is 2.65 g/cm3). Only stishovite has a comparable density of about 4.3 g/cm3.".
- Q641830 thumbnail SeifertiteStructure.png?width=300.
- Q641830 wikiPageWikiLink Q102996.
- Q641830 wikiPageWikiLink Q116269.
- Q641830 wikiPageWikiLink Q1208616.
- Q641830 wikiPageWikiLink Q17462688.
- Q641830 wikiPageWikiLink Q177342.
- Q641830 wikiPageWikiLink Q178977.
- Q641830 wikiPageWikiLink Q268771.
- Q641830 wikiPageWikiLink Q3953137.
- Q641830 wikiPageWikiLink Q407467.
- Q641830 wikiPageWikiLink Q410749.
- Q641830 wikiPageWikiLink Q410893.
- Q641830 wikiPageWikiLink Q420620.
- Q641830 wikiPageWikiLink Q422075.
- Q641830 wikiPageWikiLink Q424335.
- Q641830 wikiPageWikiLink Q43010.
- Q641830 wikiPageWikiLink Q6442973.
- Q641830 wikiPageWikiLink Q6481697.
- Q641830 wikiPageWikiLink Q648961.
- Q641830 wikiPageWikiLink Q702482.
- Q641830 wikiPageWikiLink Q7282399.
- Q641830 wikiPageWikiLink Q826582.
- Q641830 wikiPageWikiLink Q862228.
- Q641830 wikiPageWikiLink Q898974.
- Q641830 wikiPageWikiLink Q899033.
- Q641830 wikiPageWikiLink Q913970.
- Q641830 wikiPageWikiLink Q952474.
- Q641830 name "Seifertite".
- Q641830 type ChemicalSubstance.
- Q641830 type Mineral.
- Q641830 type ChemicalObject.
- Q641830 type Thing.
- Q641830 type Q7946.
- Q641830 comment "Seifertite is a silicate mineral with the formula SiO2 and is one of the densest polymorphs of silica. It has only been found in Martian and lunar meteorites where it is presumably formed from either tridymite or cristobalite – other polymorphs of quartz – as a result of heating during the atmospheric re-entry and impact to the Earth, at an estimated minimum pressure of 35 GPa.".
- Q641830 label "Seifertite".
- Q641830 depiction SeifertiteStructure.png.
- Q641830 name "Seifertite".