The material below is Open Game Content
Petrified forests: Wood turned into stone. In order for this process to take place, dead trees are usually swept away by water and collected in areas that are covered with thick deposits of mud, sand, and ash from nearby volcanoes. Over time silica permeates the dead trees on a cellular level. The minerals either take on the shape of the cells, creating a copy of the tree, or the silica replaces the wood cells, creating an inert replica of the tree. The trees are quartz or crystallized into semiprecious quartz, such as agate, jasper, onyx, carnelian, or amethyst. The petrified logs are covered by sediment that eventually becomes sandstone and shale, both relatively soft rocks. Erosion and upheaval exposes the petrified wood.
This material originates in a 3PP Source