GeoPicture

GeoPicture of the week: Tree fossil with opal growth rings

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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.

By Mihai Andrei

Andrei's background is in geophysics, and he published his first scientific paper when he was still an undergrad; now, his main focus is on how geology and geophysics can be applied to understand and protect the environment. Feeling that there is a gap between scientists and the general audience, he started ZME Science - and the results are what you see today.

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  • Black Nightshade

    wow!

  • 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.