Ann: Multiple Massive Sulphide Intersections at Mawson, page-263

Grade in pure massive sulphides at these deposits is simply a function of the three sulphide phases normally present and their percentages (with a few complicating factors)
You have:
1. Pyrrhotite - iron sulphide with a (hopefully) small percentage normally of Nickel that is difficult to recover without dropping the Ni concentrate grade. It is the dark bronze / brown sulphide
2. Pentlandite - the lightest colour sulphide, steely yellow grey. Its where the nickel is
3. Chalcopyrite - Yellow , brassy sulphide

In the attached image I have shown the Mawson massive sulphides compared to two knowns - Nova and Bollinger massive sulphide.

My "guess at grades of the massive at Mawson would be about 2.0 - 3.0% Ni and about 1-1.5% Cu

The Pentlandite and the Chalcopyrite tend the form loops around the large masses of pyrrhotite. The more "lighter" sulphides you have the higher the grade.
You need to be careful with reflections of crystal faces in the pyrrhotite looking like pentlandite.

In all these deposits, grades are quite variable through the system depending on the pulse of magma.

Definitely a good hit from Legend and there will be plenty more. IF the system is open at depth then it could be HUGE (Nova was effectively in a bowl and its feeder system most probably eroded and gone regardless of what IGO like to think)