* From an underlying abnormal excess of the mineral, e.g., with elevated levels of calcium (hypercalcaemia) that may cause kidney stones, dietary factors for gallstones. * Local conditions at the site in question that promote their formation, e.g., local bacteria action (in kidney stones) or slower fluid flow rates, a possible explanation of the majority of salivary duct<unk> occurring in the submandibular salivary gland. * Enteroliths are a type of<unk> found in the intestines of animals (mostly ruminants) and humans, and may be composed of inorganic or organic constituents. * Bezoars are lumps of indigestible material in the stomach and/or intestines; most commonly, they consist of hair (in which case they are also known as hairballs). A bezoar may form the nidus of an enterolith. In kidney stones, calcium oxalate is the most common mineral type (see Nephrolithiasis). Uric acid is the second most common mineral type, but an in vitro study showed uric acid stones and crystals can promote the formation of calcium oxalate stones.
Calculus 
Ossification
Enema
Cholesterol crystal
Granulation tissue
Neoplasm
Fibrocartilage callus
Granulation