Simply put, Petrified Wood forms when long ago a tree that fell to the ground was covered in volcanic ash or heavy sediment (think river bed). Over time, the anaerobic environment allowed for minerals like silica or quartz or chalcedony to slowly replace the cell structure of the wood. Different colors within indicate different mineral replacement episodes. The result of this eon-long creation is a gemstone that holds incredible depth and color variation. Known worldwide as the gemstone of change and transformation, petrified wood can be found the world over.