The Collaborative International Dictionary of English v.0.48:

Mintage \Mint"age\, n.
   1. The coin, or other production, made in a mint.
      [1913 Webster]

            Stamped in clay, a heavenly mintage.  --Sterling.
      [1913 Webster]

   2. The duty paid to the mint for coining. At one time people
      could bring precious metals, as gold or silver, to a mint
      and receive in return coins of the same value, minus the
      commision charged by the mint, which was the mintage.
      [1913 Webster +PJC]

   3. The act or process of minting[1]; as, a coin of recent
      mintage.
      [PJC]

   4. The quantity of coins of a specific type made by the mint;
      as, coins of low mintage tend to be more valuable as
      collectors' items.
      [PJC]

WordNet (r) 3.0 (2006):

mintage
    n 1: coins collectively [syn: coinage, mintage, specie,
         metal money]
    2: fee paid to a mint by the government for minting a coin
    3: act or process of minting coins