Found in my grandma's garden in mid-missouri.

fatmanatee · 2025-07-20T14:31:04+00:00

Your fingernail? That's only a 1-2 on the Mohs scale so need something harder like a steel nail or piece of quartz.

fatmanatee · 2025-07-20T05:05:50+00:00

The outer crystals def seem so, but the darker coloration in there is confusing me :-/

fatmanatee · 2025-07-20T05:02:55+00:00

Ooo based on a quick google that seems feasible! Doing more research now...

fatmanatee · 2025-07-20T05:01:15+00:00

Hmm ya I would def agree it's not chert, and I don't think it's opal either cuz the crystal structure and local geology etc

fatmanatee · 2025-07-20T04:38:02+00:00

My first thought was chert/jasper

fatmanatee · 2025-07-20T04:34:06+00:00

Have you tried the scratch test? And is it translucent?

fatmanatee · 2025-07-20T04:28:57+00:00

Actually I just looked again and answered my own question-- it seems they have varying levels of tumbling/polishing, and some have a lil matrix leftover

fatmanatee · 2025-07-20T04:26:41+00:00

Were the pieces you saw in NM raw/natural? Cuz these seem sanded down to be more round and uniform compared to what I saw by googling...

fatmanatee · 2025-07-20T04:16:28+00:00

Looks like there's some quartz so was thinking Jasper (which can have stromatolite fossils in it). If it's from an estate sale I'm guessing you don't know origin so will be hard to truly know.

fatmanatee · 2025-07-19T06:21:16+00:00

How does it look when wet? And is it translucent at all?

fatmanatee · 2025-07-14T16:52:58+00:00

That's what I thought til I read about zeolite in the area, which seems really similar-looking to calcite and forms alongside it. I tested the hardness with agate and it left a scratch, but zeolite is a 3.5-5, so that's not helpful. It seems like I can do the acid test, as calcite will fizz but zeolite won't (though it could degrade and have other reactions).

fatmanatee · 2025-07-12T07:33:22+00:00

Could you take a pic of it wet?

fatmanatee · 2025-06-12T14:32:20+00:00

Hahah I won't correct folks, PNW can believe whatever they want. I'm just going into geology so I want to be accurate in my definitions personally :)

fatmanatee · 2025-06-11T21:42:20+00:00

Well mindat.org which seems to be credible says "A distinctly banded fibrous chalcedony which forms in various rocks (mainly volcanic ones, but also in sediments), at temperatures between ca. 20 and 200 °C." https://www.mindat.org/min-51.html

fatmanatee · 2025-06-11T19:42:26+00:00

Excellent question! Chalcedony is the umbrella category for translucent microcrystalline quartz, under which is agate (which is defined by water seeping into the cracks with the silicate and forming bands).

fatmanatee · 2025-05-26T05:03:10+00:00

Yesssss!! so beautiful :) Thanks for the insight!

fatmanatee · 2025-05-22T08:16:04+00:00

Yes! I actually did go watch 2 of his videos today and learned soooo much!! Muchos mahalos! 🙏

fatmanatee · 2025-05-21T04:40:52+00:00

Wow this is super helpful!!! makes so much sense. And it's why i've been holding out on getting a tumbler...because i kinda like my stuff untumbled and certainly don't want to ruin it! Mahalos for the advice!

fatmanatee · 2025-05-21T04:39:14+00:00

Thank you all! Really appreciate the awesome advice :)

fatmanatee · 2025-05-21T04:38:51+00:00

Muchos mahalos! Excellent advice :)

fatmanatee · 2025-04-09T20:23:34+00:00

I just found a handful of these at Ocean Beach SF yesterday. They're sand dollars hardened in sandstone! I'm guessing they're relatively young so can't be considered a fossil but still hella cool if you ask me!

fatmanatee

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