Ann: HIGH-GRADE GOLD ZONE EXTENDED BELOW RESOURCE PIT SHELL, page-22

A mineral resource should have ‘reasonable prospect of economic extraction’ under the JORC (or equivalent) code. The company will have made some broad assumptions about annual tonnages, pit shape, mining costs, processing costs etc. If when these assumptions are incorporated the block of material is not profitable (at an $1800 gold price) then the block would be classified as waste and not part of the ounce estimate.

Note that you’ve said a ‘proven’ MRE. Terminology is important here. The MRE is not proven in any way, that term can only be used for ore reserves (require more studies).

Often companies use higher gold prices to define the pit (say US$2000/oz). This is because over the life of the pit it might be ‘reasonable’ to assume that gold prices go up. If the pit is done at too conservative gold prices then you risk sterilising a bunch of material that might one day be economic or having to spend big dollars later on a cutback.

If you want to learn about this topic suggest watching below video.