Navajo? Belt buckle

I saw this and thought sand-cast Navajo. But does the surface look right?

Id also appreciate any ideas as to age.

I don't see anything that looks like a signature.

The last picture is probably more 'natural color' than the others.

Thank you.

 

Sand or tufa stone casting,are there letters scratched on the back or just scratches?

 

As far as I can tell, they're just scratches. My eyesight's not what it used to be tho...

 

On second thought... maybe crude initials?

 

I see "EFE" or "LFE" and some sort of writing under it ? I saw some Hopi buckles that had scratched in writing,maybe its Hopi?