: calculi), often called a stone, is a concretion of material, usually mineral salts, that forms in an organ or duct of the body.

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.

Treatment varies by stone type, but, in general:[citation needed] The earliest operation for curing stones is given in the Sushruta Samhita (6th century BCE).

[2] The care of this disease was forbidden to the physicians that had taken the Hippocratic Oath[citation needed] because: The word comes from Latin calculus "small stone", from calx "limestone, lime",[3] probably related to Greek χάλιξ chalix "small stone, pebble, rubble",[4] which many trace to a Proto-Indo-European language root for "split, break up".