Onyx

Onyx is the Mystical birthstone for the month of December. It is also the birth stone for the Zodiac sign of Leo. See the birthstone list for other references to onyx. Onyx is also given on the 7th and 10th wedding anniversary. 

Onyx is relatively uncommon in nature. It is the striped, semiprecious variety of agate with white and black alternating bands. The name comes from the Greek onux, meaning "nail" or "claw", referring to the mineral's color, and it was used by the Romans for a variety of stones including alabaster, chalcedony, and what is now called onyx marble. The name onyx is properly applied only to the agate variety. Other varieties include Sardonyx, with white and red bands. As with the other chalcedonies, onyx forms from the deposition of silica at low temperatures from silica-rich waters percolating through cracks and fissures in other rocks.

Natural onyx comes from India and South America. Onyx is popular for carved cameos and intaglios because its layers can be cut to show a color contrast.

Onyx is a chalcedony quartz that is mined in Brazil, India, California and Uruguay. It has a fine texture and black color; however some onyx also displays white bands or ribbons against a black or brown background and this variety is known as sardonyx. 

The name comes from the Greek word onyx which means nail of a finger or claw. Legend says that one day while Venus was sleeping Eros/Cupid cut her fingernails and left the clippings scattered on the ground. Because no part of a heavenly body can die, the gods turned them into stone which later became known as onyx. 

Originally, almost all colors of chalcedony from white to dark brown and black were called onyx. Today when we think of onyx we often preface the word with black to distinguish it from other varieties of onyx that come in white, reddish brown, brown and banded. A variety of onyx that is reddish brown with white and lighter reddish bands is known as sardonyx.