Photo #704 – 10.19.10
Petrified Tree Stump
This is quite a cool rock! Located in the minerals section of the American Museum of Natural History in New York City, this specimen is an excellent example of a petrified tree stump. It is a bit more than a foot across in diameter, and much of the original structure (including lots of tree rings!) has been retained.
Wood becomes petrified through a process called permineralization – first, the wood becomes buried and, due to the lack of oxygen, does not decompose…then water with traces of various minerals trickles through the sediment and leaves minerals like quartz in the plant structure. Pure quartz is colorless, but small amounts of other minerals can create some crazy colors, including the reddish-orange hues in this stump that resulted from the addition of iron oxides.