Araucarioxylon arizonicum
Arizona, U.S.A.
(Dernbach Collection)

The lavenders, yellows, and reds in this specimen are typical of the rainbow wood from the Petrified Forest National Park of Arizona. The red and yellow are produced by large particulate forms of iron oxide, the yellow being limonite and the red being hematite. The purple hue comes from extremely fine spherules of hematite distributed throughout the quartz matrix, and not from manganese, as has sometimes been suggested.
Copyright © 2000 Giraud Foster & Norman Barker