I just got a pamphlet from the US Mint. It says, "These 22-karat gold coins are available in limited mintages ..." To me, this says that a AGE isn't pure gold, it's about 91% gold. But then why does it say "1OZ. FINE GOLD" on the coin? Does a gold eagle weight more than a T-OZ, so that it does contains an ounze of gold?