Interesting piece of tusk

[garyc]

I found this piece of tusk on the Brazos River in southeast Texas. I’m not seeing the typical schreger lines that determine if it’s mammoth vs mastodon. This could be Pleistocene or Miocene . The coaster is 4 inch diameter.

[Lone Hunter]

It's a rudist in disguise  Not.  It kinda looks like wood in last pictures,?

[Rockwood]

5 hours ago, Lone Hunter said:

It kinda looks like wood in last pictures,?

In those it is a dead ringer for rotten maple wood. I doubt that the concentric nature would be missing in the other views if it were wood, however. 

[garyc]

Actually, looking at my own pics again, I think I see schreger lines at te very top of the first 2 pics

[Brandy Cole]

@garycI see what you're talking about. Like top left in first pic?

 

I've gotta say if this is tusk then I've probably left some lying around thinking it was petrified wood. 

 

Thanks for sharing.

[BullStrong]

Yes, this looks like a very water warn piece of tusk to me. Schreger lines clearly visible in 1st photo.

For comparison here's an image from the gallery of Fossil Forum member Tracer. 

[Harry Pristis]

I think it's not ivory because there are no evident growth rings.

[Rockwood]

So, it's looking like, geology ?

[darrow]

15 hours ago, Harry Pristis said:

I think it's not ivory because there are no evident growth rings.

Did you mean "...not petrified wood..."

[darrow]

Appears to be Schreger line pattern inside the triangle at the upper left...

 

[Brandy Cole]

1 minute ago, darrow said:

Appears to be Schreger line pattern inside the triangle at the upper left...

 

That's what I noticed too. Also upper right corner in second picture.

[darrow]

You may find a more distinct Schreger line if you closely examine these more recently damaged areas.

 

 

The specific gravity of ivory material from that area is significantly less than the petrified wood.  It's obvious from the apparent temperature when handeling pieces and the sound it makes when struck with something like the back of a knife blade.

 

[Brandy Cole]

@darrow

Can you describe the difference in sound that you're talking about?

[diginupbones]

18 hours ago, Harry Pristis said:

I think it's not ivory because there are no evident growth rings.

 

2 hours ago, darrow said:

Did you mean "...not petrified wood..."

I believe that ivory tusk has annual growth rings much like a tree. It seems to be a very tricky thing to identify. Sometimes you can see the schreger lines, sometimes you can’t. Sometimes you can see the growth rings sometimes you can’t. Here is a similar chunk of ivory from my collection where you can see the growth rings but not the schreger lines. 

[garyc]

Better pic showing schreger lines

[Harry Pristis]

23 minutes ago, garyc said:

Better pic showing schreger lines

 

This image has all the features of ivory.

[abyssunder]

1 hour ago, garyc said:

Better pic showing schreger lines

Your picture shows the Schreger lines.

[darrow]

4 hours ago, Brandy Cole said:

@darrow

Can you describe the difference in sound that you're talking about?

The ivory sounds like a plastic material when struck while the petrified wood has a higher pitched ring to it more like a piece of ceramic tile.

 

The ivory is also MUCH softer than the petrified wood.

 

[darrow]

2 hours ago, garyc said:

Better pic showing schreger lines

 

Looks like mastodon

I should say it's not mammoth.  Probably mastdon but can't rule out gomphotherium but the latter is comparatively much more rare.

Edited December 19, 2021 by darrow

[Bone Daddy]

Here is another shot showing Schreger lines on a water-worn piece of ivory (Peace River, FL).

 

The way the specimen is fracturing is also indicative of ivory. Petrified wood tends to fracture differently (more like bone does).