here is a little more on this and by using google search you can come up with lots of info..notice how many are in the world and in Canada and this tells you a bit of the reason for the excitment..

Volcanogenic massive sulfide (VMS) deposits, also known as volcanic-associated, volcanic-hosted, and volcano-sedimentary-hosted massive sulfide deposits, are major sources of Zn, Cu, Pb, Ag and Au, and significant sources for Co, Sn, Se, Mn, Cd, In, Bi, Te, Ga and Ge. They typically occur as lenses of polymetallic massive sulfide that form at or near the seafloor in submarine volcanic environments, and are classified according to either base metal content, gold content and host-rock lithology. There are close to 350 known VMS deposits in Canada and over 800 known worldwide. Historically, they account for 27% of Canada's Cu production, 49% of its Zn, 20% of its Pb, 40% of its Ag and 3% of its Au. They are discovered in submarine volcanic terranes that range in age from the 3.4 Ga to actively-forming deposits in modern seafloor environments. The most common feature among all types of VMS deposits is that they are formed in extensional tectonic settings, including both oceanic seafloor spreading and arc environments. Most ancient VMS deposits that are still preserved in the geological record formed mainly in oceanic and continental nascent-arc, rifted arc and back-arc settings. Primitive bimodal mafic volcanic-dominated oceanic rifted arc and bimodal, felsic-dominated siliciclastic continental back-arc terranes contain some of the world's most economically important VMS districts. Most, but not all significant VMS mining districts are defined by deposit clusters formed within rifts or calderas. Their clustering is further attributed to a common heat source that triggers large-scale sub-seafloor fluid convection systems. These subvolcanic intrusions may also supply metals to the VMS hydrothermal systems through magmatic devolatilization. As a result of large scale fluid flow VMS mining districts are commonly characterized by extensive semi-conformable zones of hydrothermal alteration which intensifies into zones of discordant alteration in the immediate footwall and hangingwall of individual deposits. VMS camps can be further characterized by the presence of thin, but areally extensive units of ferruginous chemical sediment formed from exhalation and distribution of hydrothermal particulate.