Earth science Australia says this:Compositionally, VMS deposits...

Earth science Australia says this:

Compositionally, VMS deposits form two broad groups:
1.Cu-Zn - eg. Noranda, Windy Craggy, Britannia (Britannia Beach, B.C.)
2 .Zn-Pb-Cu - eg. Buttle Lake
Economically significant quantities of Au and Ag may occur in all the above lithological and compositional groups. There is only a poor correlation between the ore composition types and host rock type. Another massive sulphide category - Pb, Zn deposits -forms in a sedimentary environment VMS deposits tend to occur in districts. Up to two dozen deposits, might be clustered in an area of a few tens, of square kilometres. Known VMS districts are good hunting grounds for new discoveries. Deposits within a specific district tend to have similar metal ratios and a fairly narrow range in composition. In any given district, deposits will tend to range in size from less than one million tonnes to several tens of millions of tonnes, with most deposits at the small end of the range and only a few large deposits.