Sorry but you're going to have to wait for a lot more drilling before a model can be outlined of these chromite deposits. It will be a guessing game for a while yet.

There are however very positive indications already in hand by Noront and others in ROF with Chromite hits. One is that the strike Lenght from FWR's great hits in the North and Noront in South exceeds 10 Kilometers (backed up by gravity geophysics too).

Your probably right that 50 million tonnes would indicate an economical mine with 100 million+ tonnes being the ideal situation. However given the zone being explored a Major would likely take a position and toss in money once 30 Million tonnes are proven/indicated to fund proving up the true total size of deposit.