Rockin the Rockies

Rockin the Rockies
Stowe Mtn

Saturday, October 29, 2011

Thunder eggs vs Geodes

So what's the difference between thunder eggs and geodes.  The lady at the Rock Hound state park in NM said geodes are hollow with crystals and thunder eggs are solid.  Problem was she had numerous rocks labeled as thunder eggs that had voids in them. I tried Wikipedia for help. "A thunderegg is a specific geological structure. A thunderegg may be referred to as a geode if it has a hollow in it, but not all geodes are thundereggs because there are many different ways for a hollow to form.  Okay, so not all geodes are thunder eggs, but just because a thunder egg has a hollow doesn't preclude it from still being a thunder egg.  I guess the geological structure or formation process is the key.  Okay, here are some pictures of a geode and thunder egg?  The thunder egg was found at NM Rockhound State Park.  Yes they let you dig in a state park for rocks.
I found this thunder egg in the park.  It has a solid quartz center (Needs some polishing)

I found these nodules near the NM AZ border.  I suspected they might be geodes.
Geode with Tabular quartz crystal
Geode with dirty center (chalcedony)
Geode? No void/vug
Geode with tinted green Chalcedony

These have a hollow inside with what appear to be chalcedony





1 comment:

  1. Thundereggs are formed in volcanic flow of rhyolite. The may or may not have voids. Geodes are any blob of rock with a void no matter how they were formed. Some are calcite for instance.

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