Pancreatic stones are rare and may occur after many years of liver/gallbladder trouble. The chalky stones most often come from the gallbladder and are formed from calcium and other mineral. These are calcified stones. Those with the most calcium content tend to be white. It is possible for calcified stones to leave the gallbladder and, via the common bile duct, enter the pancreatic duct, paticularly when the duodemum is blocked or there is constipation.