Chemical Composition of Meteorites


Silicon (Si) as Silica (SiO2)

SiO2 vs. Fe2O3(T) + MgO


Many terrestrial rocks have higher concentrations of SiO2 (silica) than any meteorite. Many of these contain quartz. If SiO2 is greater than 60%, the rock is not a meteorite. The only possible exception would be a lunar granite, which is a volumetrically insignificant component of the Apollo collection. The low-SiO2 chondrites are all carbonaceous chondrites. Carbonaceous chondrites have a substantial proportion of volatile elements that, in terms of this plot, as a diluants that drag the compositions toward the origin. The low-SiO2 terrestrial rocks are mainly limestones [low Fe2O3(T) + MgO] and iron ores [high Fe2O3(T) + MgO].


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Prepared by:

Randy L. Korotev

Department of Earth and Planetary Sciences

Washington University in St. Louis

Please don't contact me about the meteorite you think you’ve found until you read this and this.


Last revised:  7 November 2018