🔎 UNIDENTIFIED Brown & black, harder than 7 mohs

[Blackfoot58]

My original thought was some type of two-tone chert. Waxy appearance and crypto-crystaline. Very hard. Well over 7 mohs.
I tumbled these with some yellow chert. The chert eventually reduced in size somewhat and lost their sharp corners. These didn’t change at all. I’m guessing much harder than chert.
They all came from the same creek in SE Iowa. I don’t think they are “special”, but I would like a good ID.
It may be a variety of chert, if so, it will not polish.
Thanks for any help.

This sample shows the 2-tone effect the best.

 

Amazon Forum Fav 👍

Cry Of The Eagle: History And Legends Of The Cherokee Indians And Their Buried Treasure - Grab it through Amazon!

[Bucket Lister]

My original thought was some type of two-tone chert. Waxy appearance and crypto-crystaline. Very hard. Well over 7 mohs.

Some cherts can run softer (6.5) but I'm sure you verified the hardness empirically.

I tumbled these with some yellow chert. The chert eventually reduced in size somewhat and lost their sharp corners. These didn’t change at all.

They look to me like they've lost their sharp edges, and only the high points appear to have the brown, suggesting that the brown may be rubbed off from the yellow chert(?)

Beyond that, they look like so many other quartzy/cherty specimens.

I think I might sacrifice one to find out if the brown/yellow runs through the stone, or if it's just on the surface.

 

[Blackfoot58]

Some cherts can run softer (6.5) but I'm sure you verified the hardness empirically.


They look to me like they've lost their sharp edges, and only the high points appear to have the brown, suggesting that the brown may be rubbed off from the yellow chert(?)

Beyond that, they look like so many other quartzy/cherty specimens.

I think I might sacrifice one to find out if the brown/yellow runs through the stone, or if it's just on the surface.

Thanks for the insight. I hadn’t considered that it might have been yellow chert originally, with a darker center. I think I will cleave one and see how it breaks and what the inside looks like. Good advice. Thanks again.
👍🏼( I’ll post the findings)