Onyx is originally an Assyrian word meaning ring. Onyx is a cryptocrystalline form of quartz. The colors of its bands range from white to almost every color (save some shades, such as purple or blue.) Commonly, specimens of onyx available contain bands of colors of white, tan, and brown.

Onyx is relatively rare. The Beinecke Rare Book and Manuscript Library at Yale University was originally planned to be coated in green onyx. However, there wasn't sufficient green onyx in the world to build such a structure