Pinophyta (conifers), Class Pinopsida, Order Pinales, Family Araucariaceae
Triassic, Norian-Carnian Stage
is 45 mm long by 45 mm wide by up to 45 mm thick; weight 174 grams.
This specimen of highly-colored petrified wood from the Chinle Formation
(Norian-Carnian Stage, ~225 million year old) deposits of Winslow,
Arizona comes with a story. Almost 25 years ago, I came across a few
examples of this rare material at a rock shop in southern Utah. I
purchased a sample, and thought little of it. After my return home,
I decided to try to obtain some larger specimens. I had been unsuccessful
until a few years ago. The rich green color is the result of ~2% Chromium
content. While the many types of petrified wood come in a panoply
of colors, only a very few types are green; the only other known to
me is found in Africa. This material comes from a small deposit near
Winslow, and is not known from any other location. Araucarioxylon
arizonicum is the state fossil of Arizona, and is the taxon comprising
some 90% of all specimens found in the Petrified Forest National Monument.
It was a coniferous tree standing some 150-200 feet tall, and some
6-8 feet in diameter. Its closest relatives today are the Monkey Puzzle
Tree of South America and the Norfolk Island Pine. All my initial
specimens are now gone; I was able to acquire a few more this year,
but have been told no more will be available from the field, as it
appears to be played out. This one has one flat side with a light
polish to show off the color.