How much do the blades on the V22 or AW609 weigh?
" However, two Osprey 38-foot rotors weigh 4,654 lbs (JANE's, 1998-9, p. 557.)" this quote is from http://www.freepatentsonline.com/8382030.html 

That would put the mass of a single V22 rotor at 1050 kg. The quoted source dates from 1998, so some improvements may have been made, but it is unclear to which parts of the rotor this refers, so it's only a guesstimate anyways.