OK I think this provides a bit of context - Just looking at...

OK I think this provides a bit of context - Just looking at their Australian website & there is this link :
Mineral Resources and Energy | Sumitomo Australia Pty Ltd (sumitomocorp.com)

But it's interesting that their investment portfolio is Eastern Seaboard according to this map :

And their partners are, from what I can see, tier one :
Strategic alliances have been formed with major mining companies, such as Glencore and Rio Tinto, with extensive development and operating experience to operate and expand our investments.
These alliances and investments in various greenfield & brownfield projects reflect Sumitomo’s commitment to the development of the mining sector in Australia.Truck & Shovel at Hail Creek
We have expanded our portfolio incrementally, and accumulated knowledge and experience in mining operations from our various investments. Sumitomo Group continues to seek opportunities for further investments both within Australia and various parts of the world.