Chemical and mineralogical development of the Sidamo nickeliferous serpentinites (Ethiopia)

The Sidamo serpentinites have developed by metamorphism of alpine-type peridotites and have been metamorphosed to talc schists, tremolite-chlorite schists and actinolite schists. Magnesite replacement, and opal and chalcedony veining result from weathering, though some magnesia and silica may have formed during metamorphism. Nickel concentration was negligible during metamorphism, but occurred to a significant extent during soil formation to form nickeliferous lateritic soils. Unfortunately most of the Sidamo serpentinites are undergoing high erosion (steep sided hills) and/or slow weathering (arid climate), so that soil formation and nickel concentration is poor.