Mightn't be a serial number. Could be a batch number or something like that, or numbered for a customer.
That one is mine , the other 2 are, 1 x from GEOMIN thread and the 2nd serial 8 I found on n Google images when I was searching GEOMIN. Trying to find a link with Perth Mint but GEOMIN is a hard one to find info on. Even when doing his research for the book he printed said he found very little but did find that GEOMIN was conected to the W.A goverment, so these may have been the start of what we now know as the early Perth Mint Ingots style Type A's / hence the OZS & FINE stamps looking almost Identical but no real run done like this in GEOMIN. Same goes for my 2 100ozs below.
^^^ The Stamp could be made by the same manufacturer at the time. Doesn't mean they came from the same smelter.
I agree Chip but what smelter were thy from if not Perth mint? do you know who made the GEOMIN ingots?
They may be associate with Anglo Gold ( Ashanti ) , which may be bought them out. GEOCHEMICAL & MINERALOGICAL LABORATORIES PTY LTD , also SGS Lab Aust that do their sample testing. I think is best to track down who they used to do theirs assaying. Those days only a few companies that do the Lab testing.
WHat was not sharted on the 100oz above is is little counter stamp on its reverse. Another new Type to add t the rare section with my other 100ozs GEOMIN's Take a look. Many Thaks to Shlomo Goldberg for the trade.
Get ready as I have 5 ultra rare GEOMINs coming all with Decimal point in weight and no letter prefix on serial. Like thisa one I wish I had not sold.
5 of the rarest 250 with decimal point and no serial prefix , Plus look carefully for the 2 sequential and the error stamped one just to top them off as a Special set.
Here are 3 of my better Geomin bars - note the no Prefix long kilo and and the R OZS and M 10oz with weak counterstamp.