Great mabe pearl clasp pearls jade and chalcedony. Double strand. Chalcedony is a very fine-grained variety of quartz. It has a waxy luster and appears in a great variety of colors -- usually blue-white, buff, light tan, gray, yellow or brown. It has a compact fibrous structure and fine splintery fracture. In the petrified forests of the American Desert Southwest, many of the original tree tissues have been replaced by chalcedony in the formation of petrified wood. What remains is a mineral replica of the original tree in various fantastic colors. The brilliant reds and greens are caused primarily by traces of iron oxides. Some of the best displays of petrified wood can be seen in eastern Arizona's Petrified Forest National Park. In all ages many varieties of chalcedony have been used as gems, and many colored varieties are still cut and polished as ornamental stones. Unless it is intricately carved or featured, Chalcedony is valued much less than it once was. It is said that chalcedony was used as a sacred stone by the Native Americas, promoting stability within the ceremonial activities of the tribe. Chalcedony is said to augment emotional balance, vitality, stamina, endurance, kindness, charity and friendliness. It supposedly alleviates hostilities, irritability and melancholy.