Petrified wood is exactly what it sounds like: ancient trees turned to stone. When wood is buried quickly in mineral-rich sediment, silica gradually replaces the organic material, sometimes so faithfully that growth rings, bark texture and even cell structure survive in quartz. The colours, cream, honey, red, purple and black, come from iron, manganese and other minerals that seeped in during fossilisation. Famous sources include the Petrified Forest of Arizona, plus Madagascar, Indonesia and Australia. Some pieces are over 200 million years old.
Because the replacement mineral is usually chalcedony, petrified wood wears like jasper: around 6.5 to 7 on the Mohs scale with good toughness. It is cut into cabochons, beads and polished slices that show off the wood grain, and it makes wonderfully conversational rings and pendants. Care is simple: warm, soapy water and a soft brush. Genuine material shows irregular, organic grain and ring patterns, which are surprisingly hard to fake well. You are quite literally wearing a piece of a prehistoric forest.
Ammolite is another fossil turned gem, and the jaspers share petrified wood's earthy palette.
