GeoPicture of the week: Tree fossil with opal growth rings

This is a part of an opalized tree, and the rings you see are actually tree rings; or at least they were.

This is an very rare sample: opal can be fairly common in petrified wood, but this is a fire opal, which makes it so much more valuable. Fire opals are transparent to translucent opals with warm body colors of yellow, orange, orange-yellow or red – basically, it often has pretty colors.

So how did this magnificent opalized tree came to be? Initially, water filled the cracks and empty spaces of the source fossil, and the silica content in the water hardened and turned into opal or chalcedony.

  • Black Nightshade


  • edwardo

    that’s gnarly

  • Orville Gates

    How old is this fossil? Or was that to much trouble to state in the article?

  • ineffableparadox

    Some 150 million years.

  • Orville Gates

    Thank you

  • Melody Anne Ribis-Roy

    I want to know where he found it? was it in Australia? that could have been stated in the story.

  • Stefanina

    This is cool.

  • Sabu’s spouse

    This is a beauty!! Who has rights to the picture? I’m an admin on a gem and mineral society page and want to use it on our page. Where can I get permission?

  • Fred Wuz Here

    It’s not a petrified tree, someone is holding that in their hand

  • Denise

    Just because it is small, that does not mean that it is not a petrified tree (or, more likely, tree branch). It is certainly petrified wood.