Rare green petrified Wood (Cr-rich) Cook Coll.

Item Description

Chromium is the green chromophore on this rare Arizona fragment of petrified wood. The Triassic-aged petrified wood contains 2% chromium, the same element that gives emerald their green color. The rare green wood comes from a small isolated deposit in the Chinle Formation near Winslow. It is a natural hygrometer, the higher the humidity, the darker deep green it turns. Old-time, seldom available material, desirable for lapidary use. 69 grams mass. I have seen these sell literally BY THE GRAM as carving and lapidary material, at Tucson. Ex Bill and Anne Cook Collection and comes with a copy of 1984 letter from the Curator of the Department of Paleobiology at the Smithsonian. The green color was originally thought to be ferrous iron, but electron probe analyses proved the coloring agent to be chromium. A UNIQUE and historical complement to this rare piece of Arizona petrified wood.