Natural (Mg,Fe)SiO3-ilmenite and -perovskite in the Tenham meteorite.
The minerals (Mg,Fe)SiO3-ilmenite and -perovskite were identified in the shock-induced veins in the Tenham chondritic meteorite. Both phases are inferred to have transformed from pyroxene at high pressures and temperatures by shock metamorphism. Columnar-shaped ilmenite grains, one of two types of morphologies, have a topotaxial relationship with neighboring pyroxene grains, indicating shear transformation. Granular-shaped perovskite grains showed a diffraction pattern consistent with orthorhombic perovskite, but these grains were not stable under the electron beam irradiation and became amorphous. The higher iron concentration in both phases compared with those experimentally reported may suggest their metastable transition from enstatite because of shock compression.
Tomioka
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Division of Earth and Planetary Sciences, Graduate School of Science, Hokkaido University, Sapporo 060, Japan. tomioka@epms.hokuda i.ac.jp
Fujino
K
K
D017610:Calcium Compounds / Q000032:analysis* / Q000737:chemistry; D007501:Iron / Q000032:analysis* / Q000737:chemistry; D058085:Iron Compounds / Q000032:analysis* / Q000737:chemistry; D017616:Magnesium Compounds / Q000032:analysis* / Q000737:chemistry; D019110:Meteoroids; D008854:Microscopy, Electron; D010087:Oxides / Q000032:analysis* / Q000737:chemistry; D011312:Pressure; D017640:Silicates / Q000032:analysis* / Q000737:chemistry; D013696:Temperature; D014025:Titanium / Q000032:analysis* / Q000737:chemistry
D017610:Calcium Compounds; D058085:Iron Compounds; D017616:Magnesium Compounds; D010087:Oxides; D017640:Silicates; C029232:ilmenite; C059910:perovskite; C034475:olivine; D014025:Titanium; D007501:Iron