Earth scientists currently use changes in major and minor elements as an indication of rock alteration. Work on spheroidal weathering has shown an increase in the rare earth element (REE) whole-rock abundancescan accompany minor changes in major elementsand highlights the need for new, more sensitive, geochemical techniques of detecting incipient alteration. Augites from the core and rind of a corestone system from the Tecuamburro complex in SE Guatemala are examined to determine their role in the whole-rock REE increases.