If for what ever reason you cant open the link, here it is:
"Judi and I were poking around a demo lot in San Francisco, when the $20 dollar Gold pieces started to turn up all over the lot. After two days of hunting, we had found 16 $20s and one $10. A few months later on the same lot, we found another $20. They ranged in date from 1877-1906, and are all San Francisco minted. What you see on the coins is rust from an apparent tin box that they were buried in. It seems obvious that they were buried before the 1906 earthquake. They aren't burned. They were found as a direct result of the 1989 earthquake, leveling an industrial building in the South Of Market district.
Thanks for looking
HH,
MT and Judi"