Volcanogenic Massive Sulfides Geologic Origins and Ores What

Volcanogenic Massive Sulfides Geologic Origins and Ores

What is a Volcanogenic Massive Sulfide? A VMS deposit is a product of hydrothermal seafloor activity in which sulfide minerals are concentrated to ore grade from a volcanic source rock.

Major Mining Operations Cyprus-type Deposits Small lenses related to basalts, Medium grade ores of zinc and copper Cyprus, Newfoundland, Oregon, Nevada Kuroko Deposits Very large deposits associated with felsic rocks in island arcs In addition to the metals found in Cyprus deposits, silver and lead are common Ontario, California, Japan. Besshi-type Deposits Form in mixed sedimentary and igneous seafloors, primarily basalt intruding sedimentary deposits Wide thin deposits Japan, British Columbia

Mining Processes Mining is both open pit and underground, relying on acid leaching or flotation to remove desired metals from the ore. Sulfide crystals may be large, grinding the ore into fine grains is often necessary. Extra precautions must be taken to isolate tailings to prevent environmental contamination, mines are often backfilled when exhausted.

Environmental Concerns of Mining Acid leaching runoff Host rocks unable adequately buffer runof Some ores must be ground finely resulting in extra reactivity of tailings from meteoric water Possible toxic levels of trace metals: Antimony, Arsenic, Bismuth, Cadmium, Lead, Mercury Ore is flammable in some cases! Toxic chemicals from refining Many chemicals used in the flotation methods are highly toxic, and must be properly recycled

Sources Taylor, Cliff D. , Robert A. Zierenberg, Richard J. Goldfarb, Robert E. Seal, and Dean R. Kleinkopf. "VOLCANIC-ASSOCIATED MASSIVE SULFIDE DEPOSITS. " <http: //pubs. usgs. gov/of/1995/ofr-95 -0831/CHAP 16. pdf>. Evans, Anthony M. Ore geology and industrial minerals an introduction. Oxford: Blackwell Scientific Publications, 1993.