Why do gall bladder stones formed?

Many possibilities: Gallstones can run in families, more common in women, more common in women who have had childbirth, and in some ethnic populations as some indians and south and central american populations. There is question of elevated cholesterol and gallstones. More common in people who have had heart surgery or other major operation. Also in those who lose a lot of weight quickly.

Stasis: No one knows how they form, but it is speculated that it is due to stasis of the bile in the gallbladder and precipitation of salts. Very much like a glass with water and salt that you let stand and the salts settles in the bottom. Gallstones are made of cholesterol and calcium usually.

Component imbalance: The principal components of bile are water, bile salts, cholesterol and lecithin. Imbalance in these components causes precipitation and stone formation. Most stones are pure cholesterol or cholesterol with calcium mixed in. Pigment (black) stones occasionally form in the gallbladder and are associated with hemolytic conditions such as sickle cell anemia and others.