According to official mint documents, 50 proof quarter eagles were produced in 1864. However, judging from the number extant, it is likely that far fewer were actually distributed. It is entirely possible that the Civil War took precedence in people's minds over coin collecting in 1864, and a fair number of those struck were melted as unsold at year's end. Only 12-16 examples are known today.
Description and Analysis courtesy of Heritage Auctions and may not be republished without written permission.