Ann: Significant pegmatite repetion encountered at Mt Cattlin,GXY-GMM.AX, page-28

Can you back this claim? From my observation the limit for most open pittable deposits is ~250m. There is the occasional super pit but most orebodies with higher concentrations of mineralization (as opposed to low-grade disseminated mineralization) have a smaller footprint... assuming 10m benches, surface mining a deposit more than 250m deep is often uneconomic because the volume of waste rock needing to be moved.