proofing piece Public Deposited
![](/assets/default-f936e9c3ea7a38e2c2092099586a71380b11258697b37fb4df376704495a849a.png)
Small bar of 999+ Fine gold, used for bringing low-grade melts up to mint standard; formerly commonly used in federal mints and in the San Francisco Provisional Branch Mint (Augustus Humbert's U.S. Assay Office of Gold).
- Breen Encyclopedia