Rapakivi granite samples were incubated withPseudomonas aeruginosaculture solutions in order to elucidate the possible role of bacteria in rapakivi (crumbling stone) disintegration. SEM micrographs showed micromorphological alterations on the incubated rapakivi surface at 21 to 23°C for 20 days. Elevated concentrations of Na, Ca, K, Fe, and Mg were detected in the culture solutions after incubation. Elemental oxide ratios [K2O : (Na2O + CaO)] in culture solutions were similar to those in rapakivi ovoids, suggesting a proportional dissolution pattern of these elements.