These minting operations were rapidly depleting the Treasury's stock of silver. Prices for the metal were rising to such an extent that, by early June, a dime contained 9.33 cents' worth of silver at market prices. On June 3, 1965, President Johnson announced plans to eliminate silver from the dime and quarter in favor of a clad sandwich with layers of copper-nickel on each side of a layer of pure copper. The half dollar was changed from 90% silver to 40%. Congress passed the Coinage Act of 1965 in July. The new half dollars retained their silvery appearance, due to the outer layer being 80% silver and 20% copper. The coin was also minted with an inner layer of 21% silver and 79% copper. The first clad half dollars were struck at the Denver Mint on December 30, 1965. They bore the date 1965; the date would not be changed for US coins until the coin shortage was eased. Beginning on August 1, 1966, the Mint began to strike 1966-dated pieces, and thereafter it resumed the normal practice of striking the current year's date on each piece. Despite the proclaimed end to the coin shortage, Kennedy half dollars circulated little, a scarcity caused by continued hoarding and a dip in production, with the Treasury reluctant to expend more of the nation's silver holdings on a coin which did not circulate. According to coin dealer and numismatic author Q. David Bowers,