Ann: Drilling Confirms A Grade K Feldspar at Sinclair, page-14

Don't want to nit pick, but we have no indication that the USD 4.8mm is all that it will cost. Also, we have to pay that back out of the Cs.
I guess it could cost $4.8mm to get down to the Cs, in which case, that is the cost of mining the Feldspar. Treating them as separate resources, there has to be a cost to digging anything up right? Hence my admittedly conservative calculation.
Doesn't seem to matter because the market simply couldn't care less by the looks of it.