Chemical Composition of Meteorites


Magnesium & Iron

MgO, Fe2O3(T), & MgO / Fe2O3 (T) vs. Fe2O3 (T) + MgO




Among meteorites, MgO necessarily increases with Fe2O3(T) + MgO. Some terrestrial rocks lie off the trend because they have MgO/Fe2O3(T) ratios outside the range for meteorites (below). High-MgO terrestrial rocks are mainly ultramafic rocks like dunites and serpentinites.



The same is largely true for Fe2O3(T). High-Fe2O3 terrestrial rocks are iron ores.



MgO / Fe2O3(T)

The ratio of magnesium to iron does not vary greatly among most kinds of stony meteorites. Rocks with MgO/Fe2O3(T) <0.2 or >6 are not probably meteorites. Only rare lunar granites have low MgO/Fe2O3(T), and none of these has been found as a lunar meteorite.


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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