Pumice

[tncrpntr]

I found pumice in the Little Harpeth River in the Nashville Tn area.  Does anyone know why it would be there?  I can't find a history of volcanic activity in the area.

[FranzBernhard]

Welcome to TFF from Austria!

 

Would you like to show off a pic or two of this material? Thank you!
 

Franz Bernhard

[patelinho7]

Pumice moves with currents very easily. It could have come from somewhere upstream where there was more volcanic activity at some point through time. I don’t know much about pumice in rivers, but it washes up on beaches in a similar fashion.

[tncrpntr]

[tncrpntr]

14 minutes ago, patelinho7 said:

Pumice moves with currents very easily. It could have come from somewhere upstream where there was more volcanic activity at some point through time. I don’t know much about pumice in rivers, but it washes up on beaches in a similar fashion.

I know, but I can't find what route it could possibly take to get here. 

[patelinho7]

Oh! That doesn’t look like pumice. Looks like an ironstone concretion to me. 

[digit]

Pumice would be EXCEEDINGLY light. It is virtually all air and the few pieces I found in New Caledonia that washed ashore from an underwater volcano in Tonga make Cheetos cheese puffs look dense.

 

My other thought for a pumice-mimic would be the inner cancellous bone material from a worn bone where the cortex was eroded away. I'm not quite getting that vibe from your images and so the ironstone may be a more appropriate diagnosis.

 

 

Cheers.

 

-Ken

[Fossildude19]

Pumice should float.

Cropped and brightened:

 

 

 

[Missourian]

Some things that could resemble pumice, more or less:

 

- Volcanic scoria - Similar to pumice in formation and appearance, but basaltic in composition; could have come from landscaping rock that ended up in the river/creek

- Slag - Glassy waste material resulting from metal smelting; can contain vesicles

- Sandstone - Missing grains on the surface could resemble vesicles; could include ironstone mentioned above (I think)

- Dolostone - Tiny fossils left as molds could resemble vesicles

- Fragmentary bone - As mentioned above by digit

 

[tncrpntr]

The material I found does float although it doesn't sit on the surface.

[digit]

Not even pumice sits above the surface of the water. If your piece is a floater and not a sinker then it has quite a lot of internal air spaces. I would have suspected it would have dropped like a rock (literally).

 

Always difficult to make out enigmatic items like this from photos alone. If you have a natural history museum nearby or a university with a geology department or even a local rock & mineral club, taking it to someone who can see it in-hand would probably get you the best answer.

 

 

Cheers.

 

-Ken

[Mark Kmiecik]

Pumice has been used as decorative material in backyards and such. That's why I never trust anything found in a developed area as something that was there originally and not brought in by man.