Can this rock be tumbled?

[artmaker]

hi, collecting rocks along lake Michigan again, want to get back into this.

So... beach rocks.

Can septarian nodules be tumbled?  Or are they too soft?  Anyone got a photo of a nice polished one?  (Assuming you can?)

Also what about coral fossils?  Ok to tumble those?

I need to get a photo of the rocks I have so far this year, but that I'll save for another thread.  Hoping to figure out what is worth tumbling and what isn't worth the trouble.

[rockpickerforever]

The determing factor on whether a septarian can be (successfully) tumbled is if it is not of differing hardness throughout. In a tumbler, this will cause it to undercut. Also, if the rock is soft, you will not get a nice polish.

Best if not tumbled, but polished on wheels, with a flat lap, or made into a sphere.

Here is a septarian sphere I picked up from someone that makes spheres in a neighboring club:
Because it was hard, it took a swell polish!


I got a really sweet deal on it, could not pass it up!  I had already commissioned him to make an obsidian sphere for me from a sphere blank I picked up at an estate sale.  He does great work!

[artmaker]

OH that is really cool!!!!!! Ok, I'm about to start another thread and already photographed mine, along with some that look similar... but not sure. Please look for that in a bit ok? Thanks.

[amygdule]

Lightning Stone is a type of Septarian from the Great Lakes region

forum.rocktumblinghobby.com/thread/70353/lightning-stone-sphere