UNITED STATES. Colorado, 'Century of Progress'. 1933. Silver "So Called Dollar." 31.25 gm. 40 mm. (.999 fine) ↑↑. Type IV. A mining scene; USE SILVER TO RESTORE PROSPERITY below; CENTURY OF PROGRESS around above; 1833 • WORLD'S FAIR • 1933 around below / Colorado State seal; ONE OUNCE OF PURE SILVER COLORADO around. HK 870. Mint State; lustrous and choice; die polishing marks both sides (as usual with this issue).