Simply put, Chromite and the market for it is not fully understood by investors as it's never been mined, to much extent, in N. America. Also the total world consumption is small compared to other metals.
This will change as the ROF deposits are more fully defined and how to economically extract and profit from them is understood. Nickel however is very well understood and shipping bulk concentrate to a number of willing buyers can be counted on.
Once a mine is justified in the ROF, bets are all being laid on Noront doing this for Nickel, then watch for how fast Chromite extraction and shipping starts getting penciled into economic justifications.
Noront's Nickel can be extracted and sold fast to recover infrastructure costs while the shear size of Chromite can justify long term amortization of a lot of the infrastructure costs therefor making the Nickel even more valuable.