Gillet P, Chen M, Dubrovinsky L
Laboratoire de Sciences de la Terre, Ecole Normale Superieure de Lyon et Universite Claude Bernard Lyon I (UMR CNRS 5570), 46, allee d'Italie, 69364 Lyon Cedex, France. Max-Planck-Institut fur Chemie, Joachim-Becher-Weg 27, D-55128 Mainz,
Science. 2000 Mar 3;287(5458):1633-6. doi: 10.1126/science.287.5458.1633.
The hollandite high-pressure polymorph of plagioclase has been identified in shock-induced melt veins of the Sixiangkou L6 chondrite. It is intimately intergrown with feldspathic glass within grains previously thought to be "maskelynite." The crystallographic nature of the mineral was established by laser micro-Raman spectroscopy and x-ray diffraction. The mineral is tetragonal with the unit cell parameters a = 9.263 +/- 0.003 angstroms and c = 2.706 +/- 0.003 angstroms. Its occurrence with the liquidus pair majorite-pyrope solid solution plus magnesiowustite sets constraints on the peak pressures that prevailed in the shock-induced melt veins. The absence of a calcium ferrite-structured phase sets an upper bound for the crystallization of the hollandite polymorph near 23 gigapascals.
在泗巷口L6球粒陨石的冲击诱导熔体脉中已鉴定出斜长石的钡硬锰矿高压多晶型物。它与先前被认为是“陨玻璃”的颗粒内的长石玻璃紧密共生。该矿物的晶体性质通过激光显微拉曼光谱和X射线衍射确定。该矿物为四方晶系，晶胞参数a = 9.263 +/- 0.003埃，c = 2.706 +/- 0.003埃。它与液相线对镁铝榴石-镁铝辉石固溶体加方镁铁矿的共生对冲击诱导熔体脉中盛行的峰值压力施加了限制。没有钙铁石结构相为钡硬锰矿多晶型物在接近23吉帕斯卡的结晶设定了上限。
