This name is often erroneously applied to the alabaster, calcite and aragonite used in the manufacture of souvenirs and other ornamental objects sold throughout the tourist centres of the Mediterranean. True onyx is simply a black and white banded variety of quartz allied to agate. These bands being straight and parallel, onyx is sometimes known as "zebra agate" or, if the stone is completely black, "black agate". During the 1950s it was very popular as a stone for men's signet rings. It is now used for intaglios and cameos, necklaces and small pieces of jewelry.

It has a very wide provenance, being found wherever there is quartz.