Gemstone ID inquiry

Hi, here are front and back views of the same stone. Can anyone tell me what it is? Fyi, it’s a stone that my wife’s late son literally found for her on a vendor “path” at Quartzite. (She was with him when he found it laying all dusty in the dirt.) It means a great deal to her. Many thanks for your assistance!

I’d be leaning towards boulder opal based on what these pictures look like. Any other thoughts out there?

Awesome. that’s guess;)

I concur. That screams opal to me also. I am working on some opals right now no that looks more like one of the black opals that I am working on. Nice find. My late husbands mother said that the Angels shadow looked like opals shimmering and from what I saw coming from her room before she passed, she was right, so I call them the angels stone.
All the best.