Found this cool rock at lake Tahoe. It has 2 white rings around it that are so perfect I thought at first they were drawn. Now it lives in my Chia pet garden. Here's an additional pic.
this post was submitted on 30 Dec 2025
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Cool Rocks
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Minerals are cool, too.
Be gneiss to each other.
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What's happened here is that when the pebble was part of the bedrock, it got shattered (probably by tectonic forces, bending the bedrock of the whole area). That left cracks all through it, at all sorts of angles.
Those cracks became spaces where water could get in, and it carried something which crystallised over the course of many years and filled the cracks.
Later the pebble broke out of the bedrock, and got eroded round. The white rings are actually flat (or at least, flattish) layers of white which cut all the way through the pebble
Whoa... So if I cut this rock open right there it would be all the way through?
Should be, yeah