1878 Trade Dollar. Proof-64 (NGC). Dusted with light golden-gray iridescence, smartly impressed surfaces are well mirrored in the fields with a soft satin texture to razor sharp design elements. The first of the Proof-only issues from the final years of the trade dollar series, the 1878 has a mintage of 900 coins. Survivors are eagerly sought by both specimen type collectors and trade dollar enthusiasts.