Petrified Wood Slab 1#1 Dimensions: 6. 5x11. 1 Thickness: 1. 9mm #2 Dimensions: 7. 7x11. 2 Thickness: 1. 6mm In the late Tertiary period, blankets of rainforest surrounding volcanoes were plentiful throughout Indonesia. After volcanic eruption these trees were buried by ash and lava eliminating any microbes that would rot the wood. the wood was then replaced with silica rich minerals such as chalcedony, quartz, calcite, opal and jasper. The beautiful colors in the wood