After the discovery of gold in California in 1849, the lack of a standard for assaying and converting oar and dust into coinage led the government to allow Augustus Humbert to operate an official assay office in San Francisco.

In 1850 a federal Assay Office was established which was authorized to issue $50 to $10,000 ingots. They were to be struck from … “refined gold, of uniform fineness, and with appropriate legends and devices, similar to those on our smaller coins with their value conspicuously marked and the inscriptions LIBERTY and UNITED STATES OF AMERICA.” The primary difference between these ingots and regular coinage was the denomination. In effect the Assay Office was a provisional branch mint. Its existence was opposed by bankers who could no longer buy gold dust for six to eight dollars per ounce because Humbert paid sixteen dollars per ounce with a small deduction for manufacturing charges.

There were at least two reasons that the government did not immediately establish a regular branch mint in San Francisco. The first had to do with the oar that was found in California. It ranged from .850 to .925 gold. Federal gold was mandated to be .900 with not more than .050 silver and the rest copper. Both copper and parting acids were required to bring California gold to the federal requirement. However, these acids were not made locally and could not be easily shipped overland or through Panama. The California gold was brought to .880, .884, .887, or .900 gold by adding measured amounts of .999 gold. The second was the legal requirement that coins could only be made at a United States Minting facility. By calling the Humbert pieces ingots and the mint a U.S. Assay Office, legal complications were avoided. However, the pieces Humbert produced circulated as coinage. Mint officials required Humbert to report monthly as if he were a branch mint superintendent. In 1853 regular coinage dies were shipped to him in the event that he might able to make legal standard coins.

The $50 Humbert Gold (Humbert Slug) or ingots were also called “Californians.” From 1851 to 1853 they were accepted as currency. The early issues had Humbert’s name and title U.S. ASSAYER OF GOLD on each piece. Later issues said UNITED STATES ASSAY OFFICE OF GOLD. In 1850 President Fillmore in fact monetized the issues of the Assay Office by declaring that they could be used to pay tariffs.

One result of the new issues was that almost all privately minted gold coins disappeared. Most of them were melted for recoinage as Humbert $50.00 slugs. As a direct result, there was a coin shortage. It made sense for Humbert to issue small denominations to meet this need; however, federal authorities did not give Humbert permission to coin smaller denominations. The result was that foreign coins began to circulate at inflated values. The state legislature passed an act that enabled private minters to issue coins in small denominations ($5, $10, and $20). Consequently, Moffat & Co. resumed issuing coinage in those denominations. Later in January, 1852, authorization was received for Humbert to mint smaller denominations. Political opposition to this ruling was shown in a law that passed in August, 1852 that required all gold pieces must conform to the standard of federal coins. News of this act created a panic. Business ceased. Coins of legal fineness could not be made because parting acids were not available and copper was very scarce. There were public demonstrations which were almost riots. Finally T. Butler King agreed to accept Humbert ingots at .900 Fine without the copper required. Local merchants agreed to cooperate, and Humbert issued $50 slugs at .900 Fine. Humbert’s slugs continued to circulate after the Assay Office closed in December, 1853 when the federal branch mint opened in the same building, using the same equipment. Federal coins began on April 15, 1854.

Designed by Charles Cushing Wright, the Humbert Slugs (Humbert Gold) were made under a subcontract from the Mint in Philadelphia. Humbert created the reverses himself. Individual punches of words, numbers were made by Georg Kuner.

The obverse of the $50.00 slug shows an eagle with wings spread partially behind a rock and shield. Behind one wing and in front of the other is a serpent, which is inscribed LIBERTY. Above the eagle is a banner with the legend 887 THOUS, which is the fineness of the gold. The design is encircled with the inscription UNITED STATES OF AMERICA with FIFTY DOLLARS below. A circle of beads surrounds this inscription. On the outside of the beads is another inscription AUGUSTUS HUMBERT UNITED STATES ASSAYER OF GOLD CALIFORNIA with the date below. The slug, also called a quintuple eagle and a five-eagle piece, had a target reverse.

 

There are several varieties of U.S. Assay Office slugs. One group has lettered edges and the other has reeded edges. The 1851 50D C 880 THOUS., with no 50 on the revere has on its edge: AUGUSTUS HUMBERT UNITED STATES ASSAYER OF GOLD CALIFORNIA 1851. Another 1851 issue has the same edge inscription but with 50 on the reverse. A third also has 50 on the reverse, but the edge lettering is 50 D C, 887 THOUS. The reeded edge varieties have target reverses. One 1851 is inscribed .880 THOUS., and the other is .887 THOUS. An 1852 slug is also inscribed 887 THOUS.

All U.S. Assay Office Humbert slugs (Humbert Gold) are rare in any condition. In its population report PCGS shows 552 authenticated in all conditions. NGC has authenticated 295 pieces. These numbers do not account for crossovers and resubmissions.

Specifications:
Edge: Lettered; Reeded
Weight: 880 Fine 1,319.3 grs., 85.49 gms; 887 Fine 1,308.9 grs., 84.82 gms; 900 Fine 1,290 grs., 83.59 gms.
Diameter: 41 millimeters (side to side), 44 millimeters (corner to corner)
Composition: 88% gold, 12% silver; 88.7% gold, 11.3% silver; 90% gold, 10% silver.