Please have a look at enclosed PDF..

Weathering intensity largely controls the degree to which primary minerals are altered to secondary components including clay minerals and oxides. ... Thus, once calibrated, weathering intensity can be used to predict a range of regolith properties. The indices you mentioned above you can apply to different rocks. But I always recommend to do not only make use of the whole-rock chemistry of them and also take into consideration the mineralogical inventory as well as the geomorphological and pedagogical part of the case history. The nature and proportions of these secondary minerals. Weathering intensity can also be determined by measuring changes in the mineralogy or chemistry of the parent material as it weathers. For example, geochemical weathering indices have been used widely to describe weathering profiles and assess the degree of bedrock weathering. These indices are based on chemical changes, often ratios of stable vs. mobile elements, from sample points through a weathering profile. Geochemical weathering indices are based on site measurements, such as geochemical composition, that cannot be easily extrapolated across the landscape.

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