Novaculite is a dense, hard, fine-grained, siliceous metamorpic rock which is a type of chert that breaks with conchoidal fracture
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
From Latin word novacula, for razor stone
From Concha (Latin)+ Coquina(Spanish) +conch(English)= Couquina (mid 19th century)
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock