But most pyrrhotite is produced by metamorphism (where rocks are...

But most pyrrhotite is produced by metamorphism (where rocks are subjected to high pressure and temperature deep within the Earth's crust) of sulphur-bearing sedimentary rocks which is the case here. These sulphide occurrences often suck up other metals like copper and zinc and so you will often get a sniff of these, but these will almost always be uneconomic red-herrings.

Yes, pyrrhotite is also found with pentlandite in nickel deposits.....but these cases are far, far less common than the occurrence of pyrrhotite in metamorphosed sedimentary rocks as described above.