Pisolite

[Image:PisolitesConococheagueUpperCambrian.jpg|thumb|Pisoids in the Conococheague limestone (Upper Cambrian) of eastern Pennsylvania]
Image:Calcario2EZ.jpg|thumb|right|Pisolitic limestone; Itaboraí, Rio de Janeiro, Brazil; pisolith diameters average 1.0 cm
Image:Qemscan_pisoliths.png|thumb|right|QEMSCAN mineral map of bauxite forming pisoids
A pisolite is a sedimentary rock made of pisoids, which are concretionary grains – typically of calcium carbonate which resemble ooids, but are more than 2 mm in diameter. These grains are approximately spherical and have concentric layers reaching 10 mm in diameter.
Bauxites, limonites, and siderites often have a pisolitic structure.