Onyx

o'niks, a term applied to two quite different stones. The first is a variety of quartz, closely allied to agate. It varies in color from white to black, brown, or red. The ancients used this stone for many artistic purposes, especially for cameos. The second onyx is a variety of marble, called also oriental alabaster. It was known to the ancients. A celebrated quarry in Egypt was rediscovered in 1850. The world's choicest supply comes from Algeria. Mexican onyx of the sort first described has a recent reputation. Ancient Aztec quarries have been reopened. This onyx is used for clock cases, bureau and table tops, vases, and for many other ornamental articles. There are fallen forests of petrified trees in the southwestern part of the United States. Entire tree-trunks have been transformed into sections of chalcedony, agate, and onyx. One of the most famous of these is the petrified forest of Arizona.