Mineral Exploration

Deposit Type References:


Volcanogenic Massive Sulfide (VMS)

VMS-Mineralization

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 formation model from Selwyn Basin, Yukon-B.C. Canada.

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-Model

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.


More deposit types coming soon!

Exploration References (Affiliates):


Mining Geology HQ recommends the following books as premier guides for general field geology and mineral exploration. Each link is an affiliate link meaning that Mining Geology HQ will earn a small percentage of sales by providing this recommendation. We aim to provide recommendations only on products we have personally used and feel would be helpful to industry geologists:

Geology in the Field
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

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.

 

Geology ore deposits

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!

Exploration Software (free):


The following software packages are not endorsed by Mining Geology HQ but are free open-source software. High-quality work can be performed on these software packages which makes them ideal for the geologist on a shoe string-budget. After all, software is just a tool to convey your understanding, experience, and knowledge. The key is quality data, well-tested hypotheses, and sound interpretations.

Geoscience ANALYST - Developed by Mira Geoscience, this 3D visualization and communication software is for integrated, multi-disciplinary Earth models and data. Check out the video here.

QGIS - Open-source GIS software.

ParaViewGeo - Open-source visualization package created specifically for the exploration and mining industry.

DXF2XYZ - Software to convert a DXF file to an XYZ file, (i.e., a comma delimited text file containing just xyz coordinates). It is useful for extracting the raw XYZ coordinates from a DXF file containing contours or other elevation entities.

3D Viewer - Simple viewer for various 3D shape files (dxf, dwg, tin, 3ds).

GCDkit - Geochemical data toolkit for handling and re-calculating whole-rock analyses from igneous rocks. It is written in R, a language and environment for statistical computing and graphics. 

Structural Geology programs - Below are hyperlinks to a variety of structural geology related software which integrate nicely with Google Earth. They are provided by Dr. Rick Allmendinger (Professor at Cornell): Stereonet 9, Faultkin 7, GeoMapDataExtractor, MohrPlotter, FaultForward v6, AreaErrorProp, plus additional utility software available from his website.