Small Black Cubes in the black sand

[bdoubleu]

Hi all. I am refining my dirt form the southwest and I am finding these very small (non-magnetic) black cubes in with the gold and black sands. Does anyone have any ideas on what this could be? I am hoping precious metal and not lead, but looking for a way to test or tell. Thanks!

 

[cosmetal]

Pictures, please . . . but, I believe that they are Devil Dice: https://www.quirkyscience.com/devils-dice-what-are-they/

Where in the Southwest?

James