In 1908, the U.S. Mint introduced a new design on the Quarter Eagle that consisted of an incused, head of an American Indian on one side, and an incused, stoic eagle on the reverse. The new type was hugely successful and the Philadelphia Mint produced over 500,000 examples to satisfy demand from the general public (this was the largest mintage since 1861). For the more sophisticated collectors, the Mint struck Proof versions with a new sandblast finish. These unusual Proofs were quite popular in spite of the dull finish, and collectors purchased 236 of them -- a record mintage for Proof Quarter Eagles until then.
Surviving examples are generally nice, appearing most often in PR64 and PR65. Superb examples are extremely rare, with only a few PR67s at the top of the PCGS CoinFacts Condition Census.