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.