We have noted that when endoscopically examining the renal papillae of patients undergoing PERC, oftentimes stones attached to renal papillae are encountered. We have collected three attached stones from three separate patients who were undergoing PERC. The stones were analyzed with a Micro CT device, and 3-D reconstruction with identification of mineral components was performed. The stones all showed multiple mineral components, including calcium oxalate, apatite, and probable regions of poorly mineralized matrix. Although the significance of these various components, in varying amounts, is not yet well understood, it is apparent that even at early stages of stone formation, multiple minerals in complex arrangement are present in papilla-attached stones. It will be only through a rigorous, prospectively designed protocol that the significance of attached renal calculi will be understood. By demonstrating that renal calculi in a population of common calcium oxalate stone formers originate from an HA plaque, we would link in a substantive way the origin of plaque with the subsequent development of stone.