Sulphide normally refers to the state/form the ore is found in,...

Sulphide normally refers to the state/form the ore is found in, which then dictates what sort of processing is required to remove the key commodity.
For example, almost all the Nickel Mines around Kambalda, Mt Keith and Leinster are Nickel sulphides deposits, and the processing of that ore is reasonably easy from a metallurgical and engineering standpoint. The processes are well established, measurable and reliable. (I think a lot of the WA gold deposits are sulphide deposits as well?)
The Nickel deposits Anaconda/Murrin Murrin etc are using are Nickel Laterites and it took them years to get the processing of that working, as it's a pressure-acid leach process which had all manner of engineering issues.
So whatever CZN are exploring for, finding the metal in a sulphide deposit should mean it's reasonable easy to process therefore more economically viable to take from an exploration hit to a mine.