Deposit Type References:
Volcanogenic Massive Sulfide (VMS)
VMS, also known as volcanic-hosted massive sulfides (VHMS) deposits, are defined as a massive accumulation of pyritic sulfides formed during discharge of hydrothermal fluids on the seafloor ("black smokers") and by replacement of reactive seafloor rocks such as shales and carbonates. The metal distribution is zoned with a decrease in Cu/(Zn + Pb) upward and outward from the base of the lens-shaped massive sulfide deposit. VMS deposits are important sources of copper, zinc, lead, gold and silver, with cobalt, tin, barium, sulfur, selenium, manganese, cadmium, indium, bismuth, tellurium, gallium and germanium as co- or by-products. VMS deposits can exhibit high metal grades with sulfide content up to 60% and are one of the more common economically exploited deposit types.
Sedimentary Exhalative (Sedex)
SedEx deposits are characterized by finely laminated sulfide minerals precipitated on the sea floor from exhaled hydrothermal fluids. These deposits are stratiform in nature but vary greatly in shape. They are similar to VMS but are hosted in sedimentary rocks (shales, carbonates), typically formed far from the vent source, and formed in fault-bounded, reduced sedimentary basins on continental crust rather than oceanic crush. SedEx deposits are the most important source of lead, zinc and barite (~50% of world's lead & zinc reserves) and can host economic concentrations of silver, copper, gold, bismuth and tungsten.
Porphyry
Porphyry Copper Deposits (PCD) are centered on a felsic to intermediate intrusive that contain disseminated sulfides with vein and veinlet-hosted silicates + sulfides. These deposits exhibit broad-scale wall-rock alteration zones formed from hydrothermal fluids in arc-related settings sourced from subduction zone magmas. PCDs are characterized by large tonnages and low grades of ore mineralization and an intrusive complexes that are surrounded by vein stockwork and hydrothermal breccias. They generally contain multiple stages of mineralizing events. Many other mineral deposit styles are associated with PCDs including: epithermal Au, carbonate replacement, and skarn deposits. PCDs represent the largest source of mined Cu and a significant portion of global Au production. The term Porphyry Copper Deposit can be misleading as there are many types including: Cu, Cu-Mo, Cu-Mo-Au, Cu-Au, Au, Mo, W-Mo, Sn, Sn-Ag and Ag.
Epithermal
Epithermal deposits are hydrothermal sourced metal deposits that form at shallow depth (1 - 2 km) over a temperature range of < 150 degrees C to 300 degrees C. These deposits are important sources of Au and Ag, representing about 30% of total Au metal production per year. There are two principal styles of epithermal mineralization: low sulphidation (LS) and high sulphidation (HS) epithermal deposits with an intermediate category sometimes recognized. The two styles are formed from fluids of contrasting chemistry with LS being geothermal based systems of near-neutral pH or reduced fluids. HS epithermal deposits are associated with acidic and oxidizing fluids formed in the magmatic-hydrothermal environment proximal to volcanic systems.
Carlin-Type Gold Deposits
Source: USGS
Carlin-type gold deposits are sedimentary-hosted, large tonnage-low grade deposits. These deposits contain microscopic gold deposited in sedimentary rocks and hosted in pyrite and arsenopyrite. This uniquely western U.S. style of mineralization was discovered near Carlin, Nevada in the early 1960s.
Compton, Robert, Geology in the Field - This is essentially the field geologist's Bible. A few chapters may be a bit out of date (mapping with an alidade anyone?) but this book is a must for any geologist.
Bates, Robert, Dictionary of Geological Terms - Another staple for any practicing geologist. There are many good dictionaries available. This happens to be one we have used and recommend.
Society of Economic Geology, 75 Years of Progress - A wonderfully detailed explanation of various deposit types with global examples by leading experts in Economic Geology.
Koger, et al., Industrial Minerals & Rocks (SME) - A required reference for anyone in Industrial Minerals. This is the latest version published by the Society of Mining, Metallurgy, and Exploration based in the U.S.
Guilbert, J. and Park, C., The Geology of Ore Deposits - The classic textbook of Economic Geology. This is a standard go-to for any geological library.
Evans, Ore Geology and Industrial Minerals - A good introduction to the basics of various deposit styles including industrial minerals deposits. The updated 3rd edition is a good one!