1999-P Pennsylvania quarter struck on an experimental alloy planchet. The coin is brassy-green colored, and closely resembles a Sacagawea dollar's metal. It is not certain what the purpose of these was, but it could be conjectured that they were experimental issues used for testing alloys for the Sacagawea dollar, which was scheduled to be released in 2000 (these are 1999 coins.) Whatever the purpose, they are rare, with approximately 5 examples known for each state quarter minted in 1999, and also an example known for the 2000 Massachusetts quarter.
A very rare state quarter issue, and an item of great interest to a state quarter or error collector.
PCGS MS-67 with blazing luster.