> To be counted as proven reserve, you need to show that the mineral is economically extractable at market prices. Specifically, by starting to extract them.

You don't need to be actually mining the stuff for it to be considered a reserve, at least in the Canadian (CIM) definitions. You do need at least a pre-feasibility study, and details on market prices & contracts.

The general point is right though, "mineral resources" means there's metal in the ground, "mineral reserves" means there's metal in the ground that can be economically mined, with consideration of the mining methods, infrastructure, legal title, environmental impact, metallurgy, market contracts, etc.