IVR's deposit is smaller but it has higher grades of silver.
IVR: 20m Oz Ag @ 110 g/t Ag + (0.6% Pb = 38,000t) http://www.asx.com.au/asxpdf/20131015/pdf/42k11syd6xfnwg.pdf
ARD: 52m Oz Ag equivalent @ 75 g/t Ag Eq (Ag, Au, Pb, Zn) or ARD (silver only): 33m Oz Ag @ 47 g/t Ag http://www.asx.com.au/asxpdf/20130301/pdf/42dd5wdv39spyb.pdf
CCU: 52.8m Oz Ag @ 63 g/t Ag + (0.8% Pb = 209,000t) http://www.asx.com.au/asxpdf/20130424/pdf/42ffpnkvcghqll.pdf