This rock is similar to oolitic limestones but contains larger and more irregular structures up to pea size, known as pisoliths. These are formed of calcite precipitated around a nucleus, such as a sand grain or a fragment of shell. The cementing material is calcite.

TEXTURE This limestone is a coarse-grained rock with pisoliths all of much the same size. These can often be flattened, unlike the spherical ooliths. Fossils are common and include many invertebrates.

ORIGIN Pisolitic limestone forms in moderately shallow marine conditions, similar to those where oolite forms. Such environments favor the precipitation of calcite. These conditions were common during the past, especially during the Mesozoic era.

Grain size: Coarse

Classification: Chemical

Fossils: Invertebrates

Grain shape: Rounded