Gallsteones:
Gallstones are basically like kidney stones and liver stones, except that they're in your gall bladder instead of liver / kidney. There are two major types of gallstones.
•Cholesterol stones: Cholesterol stones are usually green, but are sometimes white or yellow in color and account for about 20 percent of gallstones. They are made primarily of cholesterol.
•Pigment stones: Pigment stones are small, dark stones made of bilirubin, calcium bilirubinate, and calcium salts such as calcium carbonate and calcium phosphate. They account for the other 80 percent of gallstones.
•There are also some stones that are called "mixed" or "rare" stones, they're made of fatty-acid carbonates
They say pictures are worth a thousand words, so let's take a look.