This represents the very first time I have seen the round hallmark from the U.S. Mint San Francisco without a date; all others have been dated with 1956, 1958, 1959 or 1960. Thanks once again to Tammie at AU Capital Management for this unique acquisition. While there is visibly some surface marking in the area where the date is normally located, even under close loop inspection there is no evidence of any numeral.
Adding to the uniqueness of this ingot's hallmark is the loaf shape; that is a first as well. The only other totally unique shape I have seen to date is the Mint Of The United States At San Francisco "Cube" ingot. I had a chance to personally inspect it at the CyberCoins table at ANA and talk in length to Blaine about it. Both the "Cube" and now the "Loaf" represent one of a kind findings to date.
Besides the undated hallmark and "999.5 FINE" shown in the photo above, there are no other markings on the "Loaf" except the weight on the right side face from the obverse.
More to come on the U.S. Mint San Francisco "Loaf".