What are types of gall stones?

Based on composition (cholesterol, pigment and rare stones) majority (75%) are cholesterol stones (cholesterol crystals + calcium bilirubinate, subclassified into pure cholesterol and mixed stones w/50% cholesterol at least) Pigment galls stones (20% black (mostly of calcium bilirubinate) and 4.5% brown) Rare (0.5%) include calcium carbonate and fatty acid calcium stones.