In 1974 and again in 1977, the Denver Mint struck a small number of pieces on silver-clad planchets, or blanks. Both times, these came from planchets which had been shipped from the San Francisco Assay Office to Denver. The first ones in 1974 were found independently by two Las Vegas blackjack dealers. The 1974 planchets were initially intended to be used for "brown Ike" proof strikings; Mint policy then was that rejected silver proof planchets were to be used for uncirculated "blue Ikes", but these were placed in the bin for rejected copper-nickel proof planchets, intended to be shipped to be coined for circulation at Denver. The 1977 pieces resulted from pieces rejected for Bicentennial silver proof use, which were again placed in the wrong bin (they should have been melted, as the Mint was no longer striking silver uncirculated Eisenhower dollars). Between 10 and 20 of each date are known. Wexler, Crawford, and Flynn report an even rarer 1776–1976-D dollar in silver, but state that none have been offered at auction or submitted to the major coin grading services.