Definition
Diatomite is a fine-grained sedimentary rock which is formed from consolidated diatomaceous earth
Coquina is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically-sorted fragments of the shells of molluscs, trilobites, brachiopods, or other invertebrates
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock