I enjoyed reading about the hoards of proof San Francisco mint error coins that emerged from that facility in the 1970s It was intriguing to read about the Safe Deposit Box hoard.

I moved to San Francisco back in 1984 and soon found my way to Butterfields and Butterfields auction house, as it was known then. This was a rather eclectic place with many odd offerings from the city's history back to the Gold Rush. My wife and I were antique collectors (and I foreign coins) so we never failed to miss a preview. One fun event was the State of California bank box contents sale. Mostly, these contained "grandpa's coins", junk stuff like worn silver dollars and low grade gold in bulk jewelry form. I was able buy a 1909 S VDB cent in what turned out to be MS63 for a few hundred dollars, but that was "back in the day" as they say.

But the most memorable event was the proof error hoard that appeared around 1990. It's been 30 years now, but what I remember was around 100 brilliant proof S-mint US coins in a bag or box each one of which was a major mint "error." I put the term in quotes because these were so bizarre that they could only have been mint sports - multiple strikes, off-planchets, things that were less "oops" than amazing. I had by then been collecting foreign coin mint errors so I knew what I was looking at was so exceptional it was suspicious at best and criminal at worst. I could bid and two things could happen; I'd have to pay a fortune. And/or the Government would track me down and demand their return. The coins were so outlandish that they couldn't fly under the radar. Butterfields said nothing about the Secret Service blessing them. So I passed. I never checked on what the lot sold for.

In hindsight I think these were idle-time things ginned up by mint employee(s) playing around. The coins were not in flips or even envelopes, just tossed in loose. This was not the work of a numismatist, who would have been careful to package them. I suspect the "manufacturer" got cold feet and abandoned the box. It was interesting to learn from your report that the "mistake maker" was much more busy than I imagined from the bank box lot.

To read the earlier E-Sylum article, see:
ERROR COINS THAT 'ESCAPED THE MINT'(https://www.coinbooks.org/v28/esylum_v28n06a08.html)