Here's a description of exploring for Nickel Sulphides from...

Here's a description of exploring for Nickel Sulphides from Mincor at Kambalda: https://www.mincor.com.au/kambalda_nickel_operations/genesis_of_kambalda_nickel_deposits.phtml

The original formation of the river-like channels, and the pools of sulphides that developed along them, create another characteristic that is important in their exploration. That is, that nickel sulphide ore bodies tend to be elongated and ribbon-like, and present continuously or intermittently along well-defined 'channel structures' incised in the basal contact. Thus once a sulphide ore body is discovered, and the hosting 'channel structure' defined, then that channel structure can be pursued through exploration, and even where the sulphide ore body ends, further exploration along the channel is likely to discover further 'pools' of sulphides (ore bodies). This characteristic has been widely exploited by Mincor, and has led to important discoveries at Miitel, Mariners, Otter Juan and Carnilya Hill.

Note this is exactly what GBR are discovering at Eastern Mafic, that is "formation of the river-like channels, and the pools of sulphides that developed along them,..."

and there it is...they have actually made significant discovery progress, it's no surprise in the middle of this they snapped up the other available tenements...