The Coinage Act of 1792 introduced the U.S. dollar at par with the Spanish silver dollar, divided it into 100 cents, and authorized the minting of coins denominated in dollars and cents. The Gold Standard Act of 1900 linked the dollar solely to gold. From 1934, its equivalence to gold was revised to $35 per troy ounce(a troy ounce weighs 31.1034768 grams while a regular or imperial ounce weighs 28.3495231 grams). In 1971 all links to gold were repealed. Collector coins are technically legal tender at face value but are usually worth far more due to their numismatic value or for their precious metal content. Two examples are the American Silver Eagle and the American Gold Eagle, both very popular with collectors.