NaAlSi3O8-hollandite and other high-pressure minerals in the shock melt veins of the Suizhou meteorite

The Suizhou L6 chondrite contains a few very thin shock melt veins of 0.02–0.09 mm in width. In spite of small width of the veins, shock-induced high-pressure phases, such as coarse-grained NaAlSi₃O₈-hollandite, ringwoodite, majorite and fine-grained matrix majorite-pyrope_ss have been discovered in these veins. NaAlSi₃O₈-hollandite, the high-pressure phase of plagioclase, in Suizhou shock veins occurs as a single phase mineral, no silicate glassy phase, such as albitic glass, was incorporated with it. The presence of above-mentioned high-pressure phases constrains the high pressure (up to 23–24 GPa) and high temperature (up to 1900–2000°C) regime in Suizhou shock veins, and indicates that the duration of high-pressure regime in the veins should be long enough (a few seconds) for phase transformation and crystallization of minerals under pressure. The discovery of the first natural single-phase crystalline NaAlSi₃O₈-hollandite in Suizhou meteorite is of important significance in understanding the Earth’s mantle geochemistry.