Chemical Composition of Meteorites
Sodium and Potassium
Na2O and K2O vs. Fe2O3(T) + MgO
Most terrestrial rocks are richer in Na2O than any meteorite. Rocks with >2% Na2O are probably not meteorites.
Sodium and potassium are both alkali elements, and all alkali elements are in low concentrations in meteorites compared to most terrestrial rocks. Rocks with greater than 0.6% K2O are probably not meteorites.