Petrified Palm Wood (palmoxylon) Cabochon from Indonesia.
Miocene (20 million years ago).
Size: approx 7cm x 3cm
Weight: 16 g
Millions of years ago tree trunks were buried under several hundred yards of sediment. Over the course of time the wood was replaced by microcrystalline quartz, largely chalcedony and jasper. During the replacement process by silica carried in underground waters, even the most minute details of the woody structure was preserved.