The Distribution of the Chemical Elements.¹

Abstract

PETROLOGISTS generally agree that the earth contains a core of an iron alloy, most probably nickel iron with about 8 per cent of nickel, in analogy to the most common types of iron meteorites. Below the common silicate rocks of the crust there is probably a region of enrichment of heavier silicates, which have separated by crystallisation from molten silicate magma, and have settled downward owing to their high specific gravity. Probably the mineral olivine is present here in substantially larger amounts than in the average surface rocks.