LIMESTONE
Limestone is a biogenic sedimentary rock composed of the mineral calcite (CaCO3),
which bubbles in acid. There are numerous varieties of limestone (e.g.,
fine-grained limestone/micritic limestone/lime mudstone, coquina, chalk, wackestone,
packstone, grainstone, rudstone, calcarenite, calcisiltite, calcilutite,
calcirudite, floatstone, boundstone, framestone, oolitic limestone, oncolitic
limestone, etc.). The most distinctive type can be given the generalized
name fossiliferous limestone, which is composed of abundant whole &
fragmented fossil shells and skeletons. Most limestones represent deposition
in ancient warm, shallow ocean environments.
Fossiliferous limestone from the Upper Ordovician (Kope Formation, lower
Cincinnatian Series) of southwestern Ohio, USA. It is richly
fossiliferous - mostly brachiopod shells, some bryozoans, some crinoid stem
pieces, and some trilobite fragments.