Why is the Leica Mini M so heavy?

Source - PhotoRumors

Just something that makes me curious. If these specifications are correct, why is this camera so heavy and almost as big as a Leica M Rangefinder?, - nearly 700g. I assumed this would be similar to the X1 / X2 only with a zoom. However it is almost twice as heavy as both of those. I doubt the lens is responsible for the increase in weight, as again I assumed it would be similar to the X's, though slightly bigger, i.e. some kind of polycarbonate. 

Next Tuesdays announcement should be interesting. Some people seem to think this is a 'boring' camera. Not as far as I'm concerned however. I'm somewhat intrigued. I doubt we have the whole story yet.