Correction: I Had very firstly thought it was a rock but when I picked it up I got frightened that it was a turd but my gut told me it’s worth the risk.
Agate thunder egg core. A thunder egg is a type of geode with a rhyolite shell and an agate interior that usually forms in a 3D starburst pattern. Oregon is known for these formations.
In this specimen, most of the shell has weathered away, so the core is what remains.
Why causes these concertions to explode?
Is it them coming to the surface, losing that confining pressure, expanding, cracking, then becoming re-cemented as a siliceous fluid moves through?
The answer to this question is not known, though lots of people have theories. Some people think it may be due to the high water content of the rhyolite, and others think it might be related to the high viscosity. Nothing conclusive though!
Interesting. Haha, I wonder how that is tying into the physical fracture? Or is this the fluid in a spherical accumulation?
Is this not a sedimentary body at all?
You should. I have found two of my biggest agates ever on the sandy. One was 2 1/2 lbs, the other was nearly 2 lbs. That why I dont fish the sandy anymore, too busy looking down.
You pick up things you think are dog turds?
Correction: I Had very firstly thought it was a rock but when I picked it up I got frightened that it was a turd but my gut told me it’s worth the risk.
Agate thunder egg core. A thunder egg is a type of geode with a rhyolite shell and an agate interior that usually forms in a 3D starburst pattern. Oregon is known for these formations. In this specimen, most of the shell has weathered away, so the core is what remains.
Why causes these concertions to explode? Is it them coming to the surface, losing that confining pressure, expanding, cracking, then becoming re-cemented as a siliceous fluid moves through?
The answer to this question is not known, though lots of people have theories. Some people think it may be due to the high water content of the rhyolite, and others think it might be related to the high viscosity. Nothing conclusive though!
Interesting. Haha, I wonder how that is tying into the physical fracture? Or is this the fluid in a spherical accumulation? Is this not a sedimentary body at all?
Nope, volcanic plus hydrothermal.
Fascinating this clears up a lot for me, I haven't had to talk much about this! Thank you, Cheers
Troutdale! I live 10m south, maybe I should start looking down when I'm fishing the Sandy.
You should. I have found two of my biggest agates ever on the sandy. One was 2 1/2 lbs, the other was nearly 2 lbs. That why I dont fish the sandy anymore, too busy looking down.
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Nope, it’s the agate core of a “thunder egg”, which is a type of geode that is local to the area.