PISOLITE

PIS'OLITE, noun [Gr. a pea, and a stone.] Peastone, a carbonate of lime, slightly colored by the oxyd of iron. It occurs in little globular concretions of the size of a pea or larger, which usually contain each a grain of sand as a nucleus. These concretions in union sometimes compose entire beds of secondary mountains. It is sometimes called calcarious tufa.