A double eagle is a gold coin of the United States with a
denomination of $20. (Its gold content of 0.9675 troy oz was
worth $20 at the then official price of $20.67/oz). The coins
are made from a 90% gold (0.900 fine = 21.6 kt) and 10% copper
alloy. Although the "eagle"-based nomenclature for gold U.S.
coinage is often assumed to be a nickname, the "eagle," "half-
eagle" and "quarter-eagle" were specifically given these names
in the Act of Congress that originally authorized them ("An Act
establishing a Mint, and regulating Coins of the United States",
section 9, April 2, 1792). Likewise, the double eagle was
specifically created as such by name ("An Act to authorize the
Coinage of Gold Dollars and Double Eagles", title and section 1,
March 3, 1849). The first double eagle was minted in 1849,
coinciding with the California Gold Rush. In that year, the mint
produced two pieces in proof. The first resides in the
Smithsonian Institution in Washington DC. The second was
presented to then Treasury Secretary Willia