Silicon dioxide calculi in humans in the absence of silicate antacid medication

The occurrence of silicon dioxide in human urinary calculi is more common than generally believed. During a 3 year study we have analyzed about 750 human urinary calculi using the scanning electron microscope and x-ray crystallographic methods. Silicon dioxide of the alpha quartz variety was found to be the principal constituent in calculi from 5 male patients. Some of the patients were recurrent stone formers and 1 patient has previously produced a silicon dioxide calculus. In none of the 5 cases was there any history of gastric disorders or of any ingestion of antacids in the form of magnesium trisilicate. Some of the silica particles have a morphology typical of glacial sand.