Fossil - Fossilized wood from Indonesia, estimated to be over 100 million years old, dimensions 48 x 68 x 45 cm. Petrification takes place under special conditions of minimal oxidation and mechanical action and is generally associated with special conditions of volcanism or other geothermal energy, processes in which waters rich in silica or carbonates infiltrate the cells of the wood, impregnating the tissue with silicon dioxide or calcium carbonate or other minerals.