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Beach agate, possible bivalve?


winnph

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I found this on a rocky beach in West Seattle. Looks to be pretty transparent with a bit of banding. I assume it's just geological, but based on the size and shape I guess it could maybe be a bivalve fossil? SG is 2.61

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Edited by winnph
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I'm not seeing a fossil in this one.  I think your first instinct was correct, a nice piece of quartz.

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Tidgy's Dad

Very pretty indeed! i'd have it. :)

But not a fossil, i'm afraid. 

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The first two pictures remind me of percussion marks on the surface of a tumbled silica rich pebble.
Don't forget the barnacle attachment scars as a possibility for the other strange patterns. :)

 

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barnacle scars

Edited by abyssunder
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Yep, the markings are definitely percussion marks and recent barnacle remnants, the only reason I thought it could possibly be a clam cast/mold is based on the banding it is clearly an agate that filled a void in the sandstone, and it has a similar overall shape and size, kind of a flattened ovoid, but it doesn't really look THAT much like one. I'm already convinced it isn't!

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Your rock is called carnelian a type of quartz but not a true agate.I have tumble polished lots of them they are great for this and look great....,.....Steve

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Those look very nice! I am not positive that's what mine is, though, as there appears to be concentric banding that looks more like a typical agate. I took this photo yesterday before putting it in the tumbler this morning, you can kinda see the concentric banding centered near my top finger. I'll post a photo after the rough tumbling is done in a week or two, maybe we'll be able to see into it a little more clearly.

IMG_20190326_145642.jpg

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3 hours ago, winnph said:

! I am not positive that's what mine is, though, as there appears to be concentric banding that looks more like a typical agate.

Carnelian is a form of agate and can be "banded" like other agates.

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Got it! I was assuming (as is always unwise) that it would have the more "fractured" appearance of the specimens shared

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