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Nanomineralogy of Meteorites: Discovery of New Minerals Representing Extreme Conditions


Feb. 9, 2018, noon - 1 p.m.
Slichter 3853

Presented By:
Chi Ma
Caltech

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Nanomineralogy is the study of Earth and planetary materials at nanoscales, focused on characterizing nanofeatures (such as inclusions, exsolution, zonation, coatings, pores) in minerals and rocks, and revealing nanominerals and nanoparticles. With advanced high-resolution analytical scanning electron microscopy (FE-SEM with EDS and EBSD), we are now capable to characterize solid materials down to nanoscales easier and faster. Nanofeatures are being identified in many common minerals, providing insights into their genesis and physical properties. New minerals and new materials with important geological significance are being discovered at micron to nanoscales. During an ongoing nanomineralogy investigation of meteorites at Caltech since 2007, 36 new minerals have been discovered. 13 are refractory minerals like allendeite Sc4Zr3O12, davisite CaScAlSiO6, tistarite Ti2O3, panguite (Ti4+,Al,Sc,Mg,Zr,Ca,□)2O3, and rubinite Ca3Ti2Si3O12, which are among the first solid materials formed in the solar nebula. To date, ~60 refractory minerals plus ~15 presolar minerals mark the very beginning of the solar mineral evolution at 4.568 billion years ago. 7 new high-pressure minerals found in shocked meteorites are bridgmanite (MgSiO3-perovskite, the most abundant mineral in Earth), ahrensite (Fe2SiO4-spinel), tissintite ((Ca,Na,□)AlSi2O6-clinopyroxene), liebermannite (KAlSi3O8-hollandite), zagamiite (CaAl2Si3.5O11), chenmingite (FeCr2O4-CF), and stöfflerite (CaAl2Si2O8-hollandite). Each and every one of the new extraterrestrial minerals reveal distinctive forming environments, providing new insights into nebula, parent-body processes, or shock conditions and impact processes on Mars or small bodies in the early solar system. Natural high-pressure minerals also help investigations of phase transformation mechanisms in the deep Earth. Presented here are some of our discovery stories, demonstrating how nanomineralogy works and plays a unique role in Earth and planetary science research.