only certain years/mint contain 40% silver. PCGS refers to them as Type 2 & Type 4. I
these were sold directly to collectors in Uncirculated condition.
Ron Guth: In addition to the copper-nickel "clad" Ike dollars
that were made for circulation, the Mint offered an option to collectors to purchase (at a premium, of course) Uncirculated and Proof versions made of the same 40% silver composition that had been used on the Kennedy half dollars
from 1965-1970. The Uncirculated coins were sold individually in pliofilm packs inside blue envelopes, while the Proof versions were sold in GSA-style "slabs" inside a brown cardboard slipcase. All of the silver issues were struck at the San Francisco mint. All dates in this series are common, though the 1973-S Proof sells for a premium because it boasts the lowest mintage of the series.