Eagle: retired $10-based denomination of a series of gold coins
Eagle was the largest of the four United States circulating monetary denomination base-names: cent, dime, dollar, eagle. The eagle was denominated as 10 dollars in gold. Thus, quarter eagles were $2.50 in gold; half eagles were $5.00 in gold; double eagles were $20.00 in gold.
Quarter eagles were issued for circulation by the United States Mint from 1796 until 1907; half eagles from 1795 until 1929; eagles from 1795 to 1933; double eagles from 1850 to 1933, although for each of these ranges of years there were occasional gaps in production. The diameter of quarter eagles was 17 mm; of half eagles 21 mm; of eagles 27mm; and of double eagles 34mm. The purity of all circulating gold coins in the United States was 90% gold or .900 fine, which is equivalent to 21.6 karats. The weight of quarter eagles was 0.1343 troy ounces; of half eagles 0.26875 troy ounces; of eagles 0.5375 troy ounces; of double eagles 1.0750 troy ounces.
American eagle: silver, gold, and platinum bullion
The United States' circulating eagle denomination from the late 18th century to first third of the 20th century should not be confused with the bullion and collector coins named "American Eagle" which are manufactured from silver since 1986 or gold since 1987 or platinum since 1987.
