Gold bullion is available in many forms - the truth is the term bullion simply defines the mass value of the precious metal - not the face value. For example a cold coin with face value of $5 dollars is considered bullion because it's actually worth much more than $5 dollars.

Bullion also refers to bulk form precious metals. Buying gold bars, coins, and ingots would usually fall under the definition of a bullion investment.

The purity of precious metals like gold may vary, an example would be the Gold Maple Leaf coin with a rating of 99.9% purity opposed to the American eagle at 91.67%.

The lower gold content in the eagle was created for a reason. This coin has additional elements of copper and silver with the purpose to strengthen the coin.

Pure gold is a malleable, very soft metal, prone to wear. In fact gold leaf is a result of the hammering of gold and can be feather light and paper thin.