text: Any restrictions on the unspent mana aren't copied. For example, if you have {C}{W}{W}{B} with no restrictions on it and {U}{U}{U} that can be used only to cast artifact spells, you'll end up with {C}{C}{W}{W}{W}{W}{B}{B}, {U}{U}{U} that can be used only to cast artifact spells, and {U}{U}{U} that can be used for anything.