An Index of Weathering for Silicate Rocks

Summary An index of weathering for silicate rocks is proposed, based on the proportions of the alkali and alkaline earth metals present. These are considered to be the most mobile of the major elements. The bond strengths of the elements with oxygen are used as weighting factors in the index, which measures both the degree to which a rock has already been weathered with respect to the parent material, and also its susceptibility to further weathering.