Huge Onyx Wall Plaque / Aztec or Mayan Warrior /Unknown Maker / Circa Mid Century

Salvation Army has been getting in some unique things again. This incredible onyx wall plaque measures 29 1/2 " x 23 1/2" and weighs in at exactly 20 lbs ! Going to need some major hardware and a wall stud to hang it. It's carved from one slab of 3/4" onyx and is only held to the wood background with two small screws with square nuts. It looks like the real stone and not some composite resin mix. I'm not sure what type of wood the plaque is made from. It looks like walnut or mahogany to me. It's also inlaid with metal bands that surround the figure. There were only a few scratches in the wood and a little chipping to the lacquer on the metal inlay. Furniture polish made those go away for the most part. The figure itself is damage free with no chips or cracks. There are no labels or anything stamped into the wood to indicate country of origin or an artist. I strongly suspect it's from Mexico and probably dates from the 60's to early 70's. I didn't find anything online that looks even close so I have no idea of the value other than it's awesome ! -Mike-