
Based on the provided information, a 1964 Kennedy half dollar is composed of 90% silver. This specific issue, the first year the coin was minted, contains 0.3617 troy ounces of pure silver. It is important to note that the silver content of Kennedy half dollars varies significantly by the year of mintage, with the 1964 coin having the highest silver composition compared to subsequent issues which contained either 40% silver or no silver at all.


