The 90% silver Morgan Dollar coin was minted from 1878-1904 and again in 1921. This is the largest silver coin ever made for circulation in the United States; it is almost 1-1/2 inches in diameter and it contains over 3/4 ounce of pure silver. Due to their silver content, millions were melted to help pay for World Wars I and II. Many more were privately melted in the 1980s when silver prices soared. And millions were destroyed or worn out in circulation.