Sardonyx Palm Stone

Sardonyx is a gemstone that's a variant of agate, which is a member of the chalcedony cryptocrystalline quartz family. It's made up of alternating layers of sard and onyx, two types of chalcedony, that create a reddish zebra-striped gemstone with white bands. The name sardonyx comes from the Greek words sard and onyx, which mean reddish brown and veined gem. 

Sardonyx forms when silica is deposited into gas cavities in lava rock. The bands in the stone are created by layers of silica deposits that pick up different minerals at specific temperatures, resulting in sard and chalcedony in different colors. Sard can range from dark orange to red to almost black, while onyx can appear in almost any color. The most attractive sardonyx has a high contrast between the reddish layers of sard and the white bands of onyx, and it may be translucent or opaque. 

Sardonyx has been mined or gathered since before 2200 BCE and is widely available and moderately priced in sizes up to 10 carats. Some of the best examples of sardonyx can be found in India, but other deposits include Brazil, Germany, Czechoslovakia, Madagascar, Uruguay, and the United States, particularly in Oregon.