Black bile stones are composed of:
There are cholesterol stones and pigment stones. Cholesterol gallstones usually contain >50% cholesterol monohydrate. Pigment stones are composed primarily of calcium bilirubinate; they contain <20% cholesterol. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Pages 2616-17
Calcium bilirubinate stones
Cholesterol monohydrate stones
Calcium monohydrate stones
Cholesterol bilirubinate stones