MDM

These have been a mystery for me. They are unique and based on style and patina, clearly quite old. My guess is these were 70s era based on experience of looking at so many pieces from that era over the years. There are very few comps available on these. I have come across two 5 oz class previously, but the pictured ingots below are the only ones I’ve come across to date. Any help on these would be appreciated.