Sharp T G, El Goresy A, Wopenka B, Chen M
Department of Geology, Arizona State University, Tempe, AZ 85287, USA.
Science. 1999 May 28;284(5419):1511-3. doi: 10.1126/science.284.5419.1511.
Transmission electron microscopy and electron diffraction show that the martian meteorite Shergotty, a shocked achondrite, contains a dense orthorhombic SiO2 phase similar to post-stishovite SiO2 with the alpha-PbO2 structure. If an SiO2 mineral exists in Earth's lower mantle, it would probably occur in a post-stishovite SiO2 structure. The presence of such a high-density polymorph in a shocked sample indicates that post-stishovite SiO2 structures may be used as indicators of extreme shock pressures.
透射电子显微镜和电子衍射显示，火星陨石谢尔戈蒂（Shergotty）是一种冲击无球粒陨石，含有一种致密的正交晶系二氧化硅相，类似于具有α-PbO₂结构的后斯石英二氧化硅。如果二氧化硅矿物存在于地球下地幔中，它可能以后斯石英二氧化硅结构出现。在一个冲击样品中存在这种高密度多晶型物表明，后斯石英二氧化硅结构可作为极端冲击压力的指示物。
