Geology and preliminary geochemistry of the middle proterozoic serra da providencia rapakivi granite-rondonia, brazil - Rizzotto, Gilmar; Scandolara, Jaime; Silva, Cássio Roberto da; Dall'Agnol, Roberto; Bettencourt, Jorge Silva; Morais, P. R. (Symposium on Rapakivi Granites and Related Rocks, 1995)