Variety equivalents:  Unlisted in Adams-Woodin, Pollock 124

Rarity: Unique

Notes:
This unique coin is both a die trial and an intentional mint error.  The coin started out as a copper die trial of an 1846 Quarter Eagle, receiving blows from the dies used to strike regular 1846 $2.50 gold pieces.  It was later overstruck with the obverse die of an 1846 Half Eagle, after placing the die trial on a piece of leather, wood, or soft metal, thus flattening the details in the process.  Both 1846 dates are visible, as seen in the illustration shown above.

As a group, Patterns or related issues of the 1840's are extremely rare.  Die Trials are known of an 1840 Quarter, there's this coin, some Patterns of 1849, and that's it.

Images courtesy of Byers Numismatic Corp.

Known examples (1):
PCGS Proof-62 Brown (illustrated above).  Ex - ex New Netherlands ANA Sale, August 1952, Lot 4478 as "AU" - 1958 ANA Sale, Lot 469 - Auctions by Bowers and Merena, Inc., May, 1993 - Mike Byers, offered in June 2002 for $100,000.00

Sources and/or recommended reading:
"United States Pattern, Experimental and Trial Pieces - 7th edition" by Abe Kosoff (after J. Hewitt Judd, M.D.)

www.uspatterns.com

"United States Patterns and Related Issues" by Andrew Pollock