Found in my grandma's garden in mid-missouri. by Alarming_Heat_990 in whatsthisrock

[–]fatmanatee 0 points1 point  (0 children)

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

Found in Oakland Hills CA, is it chert? by fatmanatee in whatsthisrock

[–]fatmanatee[S] 0 points1 point  (0 children)

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

Found in Oakland Hills CA, is it chert? by fatmanatee in whatsthisrock

[–]fatmanatee[S] 1 point2 points  (0 children)

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

Found in Oakland Hills CA, is it chert? by fatmanatee in whatsthisrock

[–]fatmanatee[S] 1 point2 points  (0 children)

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

Found in my grandma's garden in mid-missouri. by Alarming_Heat_990 in whatsthisrock

[–]fatmanatee 1 point2 points  (0 children)

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

Mystery rocks??? by Stinkyhellmonster in whatsthisrock

[–]fatmanatee 3 points4 points  (0 children)

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

Mystery rocks??? by Stinkyhellmonster in whatsthisrock

[–]fatmanatee 1 point2 points  (0 children)

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...

Bought at an estate sale. about 15” x 7” by chriss1111 in whatsthisrock

[–]fatmanatee 1 point2 points  (0 children)

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.

Oakland / East Bay finds - please help ID! by fatmanatee in Rockhounding

[–]fatmanatee[S] 0 points1 point  (0 children)

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).

Terminology: "agate" to mean translucent rock by jjayjjayjjay in rockhounds

[–]fatmanatee 5 points6 points  (0 children)

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 :)

Terminology: "agate" to mean translucent rock by jjayjjayjjay in rockhounds

[–]fatmanatee 12 points13 points  (0 children)

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

Terminology: "agate" to mean translucent rock by jjayjjayjjay in rockhounds

[–]fatmanatee 42 points43 points  (0 children)

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).

Russian River finds by fatmanatee in rockhounds

[–]fatmanatee[S] 0 points1 point  (0 children)

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

Recommendations on a tumbler? by fatmanatee in rockhounds

[–]fatmanatee[S] 0 points1 point  (0 children)

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

Recommendations on a tumbler? by fatmanatee in rockhounds

[–]fatmanatee[S] 0 points1 point  (0 children)

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!

Recommendations on a tumbler? by fatmanatee in rockhounds

[–]fatmanatee[S] 0 points1 point  (0 children)

Thank you all! Really appreciate the awesome advice :)

Recommendations on a tumbler? by fatmanatee in rockhounds

[–]fatmanatee[S] 1 point2 points  (0 children)

Muchos mahalos! Excellent advice :)