Austin Clark, Milton Clark, and Emmanuel Gruber opened a brokerage office in Denver at the beginning of the Colorado Gold Rush (1858-1861). In 1860, they started minting $10 gold pieces; $2.50, $5, and $20 gold coins were added later. The US Treasury purchased their building and all equipment in April 1863, and they remained a bank until the first National Bank of Denver bought them in 1865.
In 1984, an 1860 $10 gold piece in mint condition (uncirculated) from the Clark, Gruber and Company Mint sold for $13,000; in 2011, it sold for $55,000; in 2014, it sold for $111,000; the 2014 gold content was worth about $900. There are only four $10 gold coins in this condition from the Clark, Gruber and Company Mint known to exist.