Assay office

Assay offices are institutions set up to assay (test the purity of) precious metals, in order to protect consumers. Upon successful completion of an assay, (i.e. if the metallurgical content is found to be equal or better than that claimed by the maker and it otherwise conforms to the prevailing law) the assay offices typically stamp a hallmark, punze, or poinçon on the item to certify its metallurgical content. Hallmarking first appeared in France, with the Goldsmiths' Statute of 1260 promulgated under Etienne Boileau, Provost of Paris, for King Louis IX.

US assay offices

Title 15, Chapter 8, Section 291 of the United States Code makes it unlawful to stamp goods in the United States with "United States assay" or any similar stamp which gives the impression that the item has been officially assayed by the United States government.

General overview and function of U.S. assay offices

Assay offices did and do exist in the U.S., but they are affiliated with the government's coinage mints and serve only the government's purposes in that field. They are not involved in hallmarking, as there has never been a hallmarking scheme in the U.S.

Assay Office (Boise, Idaho)

The Assay Office is a historic building at 210 Main Street in Boise, Idaho. It is significant for its role in the history of mining in Idaho, and was the first major federal government building in the Idaho Territory. During the first half of the 1860s, Idaho’s gold production was the third highest in the nation. Due to the difficulty of transporting bulky, heavy ores the long distance to the nearest U.S. Mint in San Francisco, there was great demand for an assaying office in Idaho. Gold and other precious metals are not mined in a pure form. In order to place a value on an ore, the precious metal must be separated from the impurities. This is what an assay office does.

The building

In 1869, Congress appropriated $75,000 to build an assay office in Boise, Idaho. The city block site bounded by Main, First, Idaho and Second was donated by Alexander Rossi, a prominent citizen of Boise. Ground was broken in 1870, and the building was completed in 1871. The builder was John R. McBride, Chief Justice of Idaho. The building featured a cupola for ventilation and the interior doors were equipped with iron cages. The first floor of the building held the assayers offices, vaults and safes, assaying and melting rooms (furnaces), laboratory and reagents storage. The second floor was devoted to living quarters for the chief assayer. There was a parlor, pantry, dining room, kitchen and three bedrooms. The basement housed fuel and supply rooms, guards’ quarters and wells.