Wednesday, June 17, 2009

Pyrolusite dendrites

Yesterday, I took a little tour out along old Route 55 through West Virginia, the road that was replaced by new Route 55, also a source of cool outcrops. My host was Maitland S., a retired gentleman who occasionally takes geology classes at NOVA. We saw a bunch of cool stuff out there, and I'll share it all with you.

First, check out these lovely pyrolusite dendrites:



Pyrolusite is MnO2, and often grows in these beautiful branching forms. It's totally an inorganic process, but the visual similarity to botanical branching makes pyrolusite dendrites a particularly insidious form of pseudofossil. Here, it's growing on limestone, presumably the Devonian Helderberg Group -- though I'll have to check on that to be sure.

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Blogger Lockwood said...

Hopefully, when they're growing on a jointing surface as in the lower photo, they're not too deceptive. :-) Those are really nice examples though.

June 17, 2009 4:04 PM  

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