Mineralogia da fra？？o areia de latossolo roxo do município de Piracicaba, SP

the mineralogy of the heavy minerals and the roundness of the quartz, of the sand fraction from the b horizons of two latossol roxo profiles, occurring in the piracicaba municipality, sp, were selected for a study on the origin of soil parent material and the presence of lithological descontinuities. the soil resulted from the weathering of basic eruptive rocks, but material from botucatu sandstone contributed for the formation of their sand fraction. the results do not confirm the lithological descontinuity in the profiles.