Interesting obsidian piece

[Out Of Time]

I think this piece is quite interesting.

Not sure how to class it; projectile point or something else?

Check out the unusual wear or corrosion on one face, anybody seen that before?

It's a creek find from Napa, Ca.







Thanks for looking.

 

Amazon Forum Fav 👍

Family Maps of Hinds County, Mississippi, Deluxe Edition - Grab it through Amazon!

[Rookster]

If it's a projectile point, they weren't that good a shot. Just kidding. Nice find.

 

[arrow86]

I would guess it was a knife / scraper , you find some really worn down obsidian .... do you also find stuff made from translucent , glass like obsidian ?

 

[Out Of Time]

I would guess it was a knife / scraper , you find some really worn down obsidian .... do you also find stuff made from translucent , glass like obsidian ?

I do find obsidian almost exclusively.

Most comes from the Napa source and is opaque, but some comes from Clear Lake source and that can be quite translucent.

Here are some examples of two different Clear Lake obsidians both translucent.

 

[Out Of Time]

Close up on 'pocking'.

I doubt that was in the original lithic as it would seem to be disqualifying.

What could cause that kind of wear?

Or, perhaps, they are bubbles that were concealed in the material and then were exposed through wear.

 

[Kray Gelder]

View attachment 1730832

Close up on 'pocking'.

I doubt that was in the original lithic as it would seem to be disqualifying.

What could cause that kind of wear?

Or, perhaps, they are bubbles that were concealed in the material and then were exposed through wear.

That looks like fire damage.

 

[welsbury]

To me it looks like normal crust on OBS,yours is heavily worn. If you were to go to a flow nearby you would see this same thing without the wear. I see it on our obs regularly

 

[Out Of Time]

To me it looks like normal crust on OBS,yours is heavily worn. If you were to go to a flow nearby you would see this same thing without the wear. I see it on our obs regularly

Do you mean it's often found on cortex?

That's not the case with obsidian round here, at least I've never seen it before on either cobbles, cores or worked pieces.

This is why this forum is so great, always learning.

 

[Out Of Time]

That looks like fire damage.

That's an interesting idea.

Would love to see some examples of fire damaged lithics.

Off to google.

 

[Tdog]

Do you mean it's often found on cortex?

I think he's saying it is Part of the cortex or maybe heat created the cortex as it exists right now. I think that is a plausible explanation.

 

[Kray Gelder]

That's an interesting idea.

Would love to see some examples of fire damaged lithics.

Off to google.

Obsidian is a glass, and I have seen fire damaged bottles. Just an idea.

 

[Out Of Time]

Ok, this solves it for me.

Fire damage as Kray Gelder says is the most likely explanation.

Excerpt from paper named 'Fire Effects on Flaked Stone, Ground Stone, and Other Stone Artifacts'

"Obsidian is thermally affected at varying temperatures and at differing lengths of exposure to heat. In field and lab fire experiments, obsidian has been reported to fracture, crack, craze, potlid, exfoliate, shatter, oxidize, pit, bubble, bloat, melt, become smudged, discolored, covered with residue, or rendered essentially unrecognizable"

https://www.fs.fed.us/rm/pubs/rmrs_gtr042_3/rmrs_gtr042_3_097_111.pdf

Worth reading.

I'm sure welsbury is right about vesicles being common on Oregon obsidian but I don't think it is on Napa's.

 

[Out Of Time]

Obsidian is a glass, and I have seen fire damaged bottles. Just an idea.

I think you are right, good call, thanks.

 

[pghDFXer]

Might be pine pitch, take a lighter to it

 

[A2coins]

Thats a great artifact Well done