Key Date Confusion

From the CCF Glossary (links on the left side):

Key Coin
The major, or most important, coin in a particular series. The "key" coin is usually the lowest-mintage coin and/or the most expensive coin in a particular set. The 1916-D dime, for instance, is usually considered the key coin of the Mercury dime series. It is the lowest mintage coin of the set and the most expensive (in most grades). The 1919-D dime is the "condition rarity key" of the Mercury dime series, as it is the most expensive coin in top condition.

The key date is relative to the other coins in the particular series; therefore, just about every series has a "key date" needed to complete it. I would consider that 1802 half-dime a key date!

You will never walk into a dealer and have him hand you an 1802 Half Dime because I can almost guarantee that the dealer has probably never handled one either! Considering that PCGS and NGC have a combined population of 14, not many people have ever even seen one. You are talking about key coins and the 1802 Half Dime is a KEY coin in a class with few other coins. There are really two kinds of keys- the ones that most can hope to attain one day(1909s VDB, 1916D Merc, etc) and the ones we can only drool over looking at pics from Heritage Auctions(1802 Half Dime, 1876CC 20 cent, 1878-S SL half, etc)

Chances are my coin shop has actually had an 1802 Half Dime in their possession. -PP