Terrestrial Ratio of Potassium to Rubidium and the Composition of Earth's Mantle.
The ratios of potassium to rubidium determined for a series of oceanic volcanic rocks suggest that the K/Rb ratio of the upper mantle exceeds 1500. The similarity between this inferred K/Rb ratio for the mantle and that found in some achondritic meteorites suggests a similar overall composition for these materials.
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