Letter X Y Z
Set of coins for any specific year containing one of each denomination of that year.
Those 1921 Morgan dollars specially struck for numismatist and Mint friend Farran Zerbe. These Proofs are not of the same quality as the other Proof Morgan dollars. The devices on these specimens usually are not frosted while the fields lack the depth of mirror normally associated with Proofs. In fact, the fields are characterized by heavy die polish, the planchets likely not burnished before striking. (Both Philadelphia and San Francisco examples are known.)
A grey inexpensive metal, usually alloyed with copper to make brass coins, but is also used in pure form for emergency coinage when the usual coinage metal is not available due to war or other serious crisis. Much of the coinage struck in Nazi-Occupied Europe was tin-plated zinc.