Olde Tyme Photo ...?

I found this while going through my mother's estate.  It looks like a old photo - but not of a type I recognize (it's not a daguerreotype - at least I don't think so)  It's approximately four inches by three.It's on a textured, non-magnetic metal.  The texture is diamond shaped.  I posted a closeup of the texture it that helps.

The frame is modern, pretty, but not valuable.

I'm curious as to the subject as well.