<prompt> Radiolucent stone isOxalate calculusPhosphate calculusUric acid calculusCysteine calculi  <response>: Uric acid calculus 1317-LB 1296-B L 25th About 90 of calculi are radiopaque calcium, phosphate oxalates, cystine Uric acid stones are radiolucent and appear on an excretion urogram as a filling defect Spiral CT has become the study of choice in emergent situations, as the entire urinary tract can be scanned rapidly and without contrast injection. 1042-CSDT 11th 