|oolith (ō'ə-līt') Pronunciation Key
A small, round grain consisting of calcium carbonate, silica, or dolomite. Ooliths have concentric layers that form around a nucleus, such as a shell fragment, a sand grain, or a pellet of alga. They typically have diameters of 0.25 to 2 mm. Ooliths usually form by inorganic precipitation.