So someone else had a piece with this hallmark (I’ll try to find that thread), and I thought it was the same as what is on my saguaro pendant. But now that I looked at it again, it is not exactly the same. Here is what is on my pendant.
When I mentioned that R Livingston was a Navajo, I wasn’t home and couldn’t see the hallmark. Now I don’t know if this is the same person 
mark is different.
Found it…Saved from the fire pit