Ron Guth: The Philadelphia Mint made so many pattern coins in 1870 that they merit their own category on PCGS CoinFacts, a unique situation in the world of pattern coins. We concur with Q. David Bower's description of 1870 as "...the greatest pattern zoo of all time..." The 10th edition of Judd lists 258 different types and metal combinations -- just for 1870.
This year saw the heavy use of silver, copper, and aluminum for pattern coins, with an occasional Nickel, Brass, or Copper-Nickel coin thrown in for good measure. There is even an unusual bi-metallic coin made of rolled silver and copper (the unique J-793a). No gold pattern coins were made in this year.
The STANDARD SILVER series was continued in 1870 along with some new obverse designs by William Barber. Off-metal Proofs were made of the regular-issue denominations, including the gold. Some patterns on this year were sold as part of matching, nine-piece sets.