I don't see how one kind of pure ice can be denser than another--unless, of course, it's not pure.

Impurities, such as salt, might make ice denser, but I think they would also lower the freezing/melting point, so the ice would melt faster.

If ice were even 10% denser than it is, it would sink! (In fresh water, anyway; the percentage would be higher for salt water, but I don't know how much.)