In the Tertiary period, blankets of rainforest surrounding volcanoes were plentiful throughout Indonesia. After volcanic activity, these trees were buried by ash and lava, eliminating any microbes that would rot t he wood. The wood was then replaced with silica rich minerals such as Chalcedony, Quartz, Calcite, Opal, and Jasper. The beautiful colors in the wood come from assorted trace elements. Traces of manganese create blue and black colors, and traces of iron would result in different shades of brown and orange. 

This petrified wood from Indonesia is millions of years old.