There were no 40% silver San Francisco Mint bicentennial quarters struck for general circulation. All of the 40% bicentennial silver quarters with an S mint mark were placed in special three piece uncirculated and proof sets consisting of the quarter, half, and dollar for collectors. The San Francisco Mint also struck copper-nickel clad 1776-1976 dated six piece proof sets consisting of the cent through dollar. Any 1968 and newer S mint coins found in circulation were broken out of their original government packaging and spent. The only circulating 40% silver coins were the half dollars of 1965 to 1969, the 1970-D was only available in mint sets.