Latin: onyx - "nail'', or marble onyx consists of concentric calcite or aragonite layers, which have precipitated in cold water in caves, clefts and near underground wellspring openings. Marble onyx depending on its composition and origin is closer to marble than to the real onyx. The real onyx is a subtype of Chalcedon and consists mainly from silica. Marble onyx formerly was called “alabaster”, while nowadays alabaster is named after marble onyx.
