By the end of the summer of 1849 many different privately-issued gold coins of varying quality were in circulation. Some of these pieces were of nearly full intrinsic gold worth. Others were considerably debased. Among those issuing debased pieces was Wright & Co., which on August 7, 1849 requested permission to issue gold coins of the $5 and $10 denominations. They stated that they were willing to post performance bonds and that their coins would be equal to the intrinsic value of the pieces produced by the United States Mint. The proposal was rejected.
Wright & Co., Exchange Brokers, was located at the corner of Washington and Kearny streets, Portsmouth Square, San Francisco, early in September 1849. During the following November they organized as a banking firm. Composing the company were Stephan A. Wright, John Thompson, Samuel W. Haight, and J.C.L. Wadsworth. Known as the Miners' Bank, the institution was housed in a wooden framed structure for which $75,000 rent per year was paid! It is believed that coins of the denomination of $10 were produced by the firm in the autumn, apparently before the November 1849 partnership was completed, for William P. Hoit, assayer of the New Orleans Mint, reported on December 13, 1849 that he had assayed a Miners' Bank $10 nearly two months earlier:
On the 16th of October I assayed one ten-dollar piece coined at San Francisco, nearly a facsimile of the United States gold eagle (Moffat & Co.); weight 258 grains; title 888 milliemes of gold, 60 do. of silver, and the balance of copper; value $9.78. This is the only coin in which art has been resorted to in making an alloy that I have seen. Also on the same day one ten-dollar piece of the Miners' Bank of San Francisco; stamp very different from that of the U.S.; weight 259 grains, title 866 milliemes of gold, 105 do. of silver, value $9.65.
As the intrinsic value of the Miners' Bank pieces was significantly below the face value, the issues were not readily accepted. On December 14, 1850, the company dissolved. The issue of Alta California dated April 11, 1850, reported that:
The issue of the Miners' Bank is a drug on the market. Brokers refuse to touch it at less than 20 percent discount. Moffat's issue will probably soon be no better; he already refuses to redeem it in American gold. Those who have it would do well to get five-franc pieces to the dollar, which is really 7 percent discount for it, at Moffat's counter now, as it is not impossible that they may refuse to pay even that for it soon.
So far as is known, only one issue was ever produced by Miners' Bank, the $10 denomination. As these pieces were rejected in their own time, very few have survived to the present day.
