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Seifertite

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Formula:
SiO2
System:
Orthorhombic
Name:
Named in honour of Dr. Friedrich Seifert (1941- ), founding Director of the Bayerisches Geoinstitut (Bavarian Geoinstitute) at Bayreuth, Germany.
The densest and hardest polymorph of silica found in nature so far, with a structure similar to that of alpha-PbO2. Found first in the Shergotty meteorite, and since then in several other Martian meteorites. Stable only above pressures of 780 kilobars, so it could theoretically also form in the Earth's mantle at depths over 1,700 km, if any free silica is present.

Classification of Seifertite

Approved 2004
4.DA.50

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
A : With small cations: Silica family
75.1.6.

75 : TECTOSILICATES Si Tetrahedral Frameworks
1 : Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
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Type Occurrence of Seifertite

General Appearance of Type Material:
lamellae occurring in composit silica grains
Geological Setting of Type Material:
Presumably formed by impact shock in basaltic Mars rock.

Occurrences of Seifertite

Geological Setting:
Meteorites derived from Martian basalt.

Physical Properties of Seifertite

Density:
4.294 g/cm3 (Calculated)

Crystallography of Seifertite

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:
Pbcn
Cell Parameters:
a = 4.097(1) Å, b = 5.0462(8) Å, c = 4.4946(8) Å
Ratio:
a:b:c = 0.812 : 1 : 0.891
Unit Cell Volume:
V 92.92 ų
Z:
4

Chemical Properties of Seifertite

Formula:
SiO2
Essential elements:
All elements listed in formula:
Empirical Formula:
SiO2

Relationship of Seifertite to other Species

4.DA.05QuartzSiO2
4.DA.10OpalSiO2 · nH2O
4.DA.10TridymiteSiO2
4.DA.15CristobaliteSiO2
4.DA.20MogániteSiO2
4.DA.25Melanophlogite46SiO2 · 6(N2,CO2) · 2(CH4,N2)
4.DA.30LechatelieriteSiO2
4.DA.35CoesiteSiO2
4.DA.40StishoviteSiO2
4.DA.45KeatiteSiO2

Other Names for Seifertite

Name in Other Languages:
German:Seifertit
Simplified Chinese:塞石英

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Seifertite

Reference List:
A. El Goresy, P. Dera, T.G. Sharp, C.T. Prewitt, M. Chen, L. Dubrovinsky, B. Wopenka, N.Z. Boctor, R.J. Hemley (2008): Seifertite, a dense orthorhombic polymorph of silica from the Martian meteorites Shergotty and Zagami. European Journal of Mineralogy 20, 523-528.

U. Bläß, F. Langenhorst (2011): High-pressure phase transformation of SiO2 polymorphs to Seifertite. Joint Meeting of the DGK, DMG and ÖMG, Salzburg, Austria, September 20-24, 2011; Abstracts Volume, p. 46.

Internet Links for Seifertite

Localities for Seifertite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
Algeria
 
Shohei Kaneko, Eiji Ohtani, Masaaki Miyahara, Takeshi Sakai, Masahiro Kayama, Hirotsugu Nishido, Yasuo Oishi, Naohisa Hirao (2011) Dynamic event recorded in a lunar meteorite NWA 4734. Japan Geooscience Union Meeting Makuhari, Chiba Japan.
India (TL)
 
  • Bihar
    • Gaya District
El Goresy, A. et al. (2008):European J. Mineralogy 20,523-528.
Nigeria
 
  • Katsina State
Zhidong Xie et al. , Lunar and Planetary Science XXXVI (2005), 1216.pdf
Mineral and/or Locality  
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