Encrinite

In its modern usage, which was established by Bissell and Chilingar, an encrinite is a crinoidal limestone containing crinoid ossicles in excess of 50 percent of the bulk of the rock. In terms of Dunham's classification of carbonate sedimentary rocks, it could be either a crinoidal packstone or crinoidal grainstone. In terms of Folk's classification of carbonate sedimentary rocks, an encrinite would be either a crinoidal biomicrite, crinoidal biosparite, crinoidal biomicrudite, or crinoidal biosparudite. In older literature, the word is sometimes used to refer to a crinoid, especially a fossil crinoid belonging to or like one belonging to the genus Encrinus. However, this usage is obsolete.

Ausich regards the term encrinite as being of very limited usefulness in modern sedimentology. Although it certainly describes a specific type of sedimentary rock, it ignores specific characteristics of crinoid-rich limestones, e.g. whether it has a mud matrix or spar cement, that are essential to recognizing their facies and origins. As a result, the term encrinite lacks usefulness in the current classification and nomenclature of sedimentary rocks and is, at best, a relict of the early nomenclatural history of sedimentology.