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About Minerals

Petrified Wood

(some of this information came from the internet from free sites)

Literally the name means “wood turned into stone” from the Greek word petro. All the organic materials within the wood have been replaced by minerals (silicate or quartz) while keeping the structure of the wood intact. Other plant fossils are impression or compressions while wood is a three dimensional fossil. The petrification process occurs when the wood becomes buried under sediment and is initially deprived of oxygen which slows down aerobic decomposition. Mineral laden water flowing through the sediment deposits minerals in the wood cells, and as the lignin and cellulose decay a stone replacement forms.

Elements in the water/mud give petrified wood a variety of colors. Carbon-black; Cobalt-green/blue; Chromium-green/blue; Copper-green/blue; iron oxides-red, brown and yellow; Manganese-pink/orange; and Manganese oxides-black/yellow. Almost all of these colors are present in the Arizona wood.

Some petrified wood can preserve the original structure of the wood in every detail down to microscopic level and structures of the tree such as growth rings and the various tissues are often seen. There is another web site called Echoes of the Past by a self taught paleobotanist named Ed Strauss who has identified 22 species of wood found in Western Washington. Great reading. Some of us have taken classes from a paleobotanist named Walt Wright. I “googled” Walt Wright and came upon Walt Wrights Petrified Wood Display, at a big rock show in California. Look it up!! Wonderful. He is marvelous and able to impart his vast knowledge so it is comprehensible to newbies like me!

Petrified wood has a Mohs hardness of 7, the same as quartz crystal. —Just as a matter of interest—It is the provincial stone of Alberta and the state stone of Washington.

Bev Bockman