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Details of US Mint gold deposits

7 posts in this topic

We collectors usually ignore the incoming, or deposit end of the coinage business, yet that is what supplied the silver and gold required for manufacturing coins. The following photo is a detail taken from the San Francisco Mint’s weekly report on gold deposits. Most of the column titles are self-explanatory, but a few terms used in the “Description of Bullion” column might be unfamiliar to readers.

 Amal = amalgam = gold extracted from crushed ore using mercury; some of the mercury remains.

Grains = placer or gold dust particles.

Jew[elry]. ingot = gold jewelry indiscriminately mixed and melted into a bar.

Balls = roughly pressed amalgam in baseball-size spheres.

King = a cone or dish-shaped piece of gold retrieved from the bottom of a crucible.

Cake = mercury-gold amalgam pressed into a short cylinder about 4-in thick and 10-in diameter (varied widely); pressing usually done in remote areas with a simple lever press (looked like big garlic press), mints/assay offices used a small hydraulic press.

Sovereigns = standard British Empire gold bullion piece; Imperial standard.

Bars = usually melted placer grains and dust; not refined.

French gold = coins or bars of the French coinage standard of 0.900 fine; variable alloy but copper if coins.

In far right column the term “dirty” indicates that the Melter & Refiner found a lot of sand, magnetite and non-gold material mixed in the deposit.

Jewelry deposits were usually inspected before acceptance and plated items were refused. The Deposit Clerk could also reject any deposit that was exceptionally dirty, and could hold bars pending drilling is he was suspicious of the color or weight. A common fraudulent practice was to cast low fineness bars, then plate them with nearly pure gold and pass the whole thing as pure. Since the Mints and Assay Offices did not pay for deposits until they had been melted and assayed, it was rare for a bad deposit to be accepted. The minimum deposit value was $100 although that regulation was not strictly enforced at times.

18730905 SF Weekly gold deposit table-detail.jpg

Edited by RWB
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1873. Bottom half of the sheet is similar to this portion. Once, there must have been hundreds of these.

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  • Member: Seasoned Veteran

It's a good thing that labor was cheap and handwriting superb.

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Members should note that losses refer only to weight. The purity (fineness) had not been determined at the point where this form was completed.

Handwriting was likely that of the Deposit Weigh clerk with each entry being made when the gold was presented, then updated after melting. A matching table contained assay results for each deposit and the net gold value. California native gold contained silver and usually, iridium & osmium, plus platinum. For modern identification of gold-rush era sources, these trace elements and their proportions can indicate a specific region or mine as origin of the gold.

Edited by RWB
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I would like to add some more SFBM gold deposits to the list circa 1854-1857.

Under Gold Bars-Assayed bars which sometimes included the serial number on the bar i.e. No. 2110 or 2958 or 761, 714 

On rare occasions the maker or assaying firm that poured the bar was listed with the letter K for John Glover Kellogg . I saw one of his bars assayed at 998 fine he must have been showing off. In one deposit the Mint employee wrote Kellogg assayed bar. 

Sometimes the deposit designation was refined gold bar no assayer listed

Sometimes the designation was small bars

Also saw a counterfeit bar rejected

In 1857 Justh & Hunter deposited a large number of “assayed and toughened bars” at the mint. All were above 900 fine with one small 14 ounce bar topping out at 998 fine. They had a refinery.

All of the gold ingots recovered from the wreck of the S.S. Central America bearing their hallmark were not refined. They were basic California gold Assay bars. No attempt was made to remove the silver from the deposited gold.

Of course gold coins were deposited at the SFBM including Kellogg coin’s and a number of octagonal slugs. 

The Mint workers would write coins, slugs or slugs with the deposit face total  like $19,300 or Slugs and then break the deposit down into fineness numbers like 900, 887, and 880.

On very rare occasions Wass, Molitor & Co. coins were specifically listed as being melted along with the notation of $10 pieces or $50 pieces

Gold from Australia was also deposited at the SFBM during this time period. The specific locality of the CA gold deposit was usually not noted unless it was Kern River gold 

RWB is right about Iridium I saw that mentioned in the SFBM gold deposits records and letters.








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You ought to compile the images and data you have and send it it NNP. San Francisco Mint archival data is mighty scarce.

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