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Geochemistry 

 
Authors: Jack Caldwell

Summary

This review describe the geochemists I have worked with, the science and technology of geochemistry, the software to undertake mining-related geochemical evaluations, and the consultants who service the mining industry in the field of exploration and environmental geochemistry.

INTRODUCTION

But before we proceed, if you are in a hurry for details on geochemistry go to one or more of these links www.geotech.org,
links of interest in GeoChemistry, Open Directory Project, Geo Pages or simply do a Google search with keywords that narrow the field to your specific interest. But be warned, keywords geochemistry association yield over one million hits, so what follows is intended to speed your way through the wilderness of machine hits.

Geochemists I Have Known


My introduction to geochemistry was via Dr. A (not his real name). We had a heated debate about calling a chemical recalcitrant. That is what my mother called me, and I objected to applying so maternally-loaded a term to a chemical. Sober the next day I yielded ground and we were friends thereafter. I shared a house with him for three month and argued only once more. He decided it would be healthier to eat vegetarian, so we tasked the white-coated cook of the sprawling northern-suburbs house to load the table with good cheeses, fine nuts, and expensive wines. After three months and ten extra pounds, I went back to meat as a way to control my weight, as did Dr A. Jensen Cation Plot

I learnt the basics of geochemistry from Dr. A on the first job we did together. A coal mine asked me to look at cracking of the floor slab in the new community center dining room. There were huge cracks about a meter away from and all around the perimeter. The fill beneath the slab was dry, sound, permeable rock. I could not explain the obvious lifting of the slab on the basis of the theory or practice of heaving clays as taught me by Professor J. The only thing that could possibly be increasing in size was the mass of rock beneath the slab, but whoever heard of rock increasing in size or volume?

Over fine wine and too much good cheese I cogitated with Dr. A on this problem. A slew of testing of the physics and chemistry of the rock, and he proved that some chemical coating the bedding planes of the intact rock pieces was increasing in size due to the new presence of moisture—the rock was run-of-mine underground-derived waste rock now exposed to the moist environment. This tiny bit of chemical-related expansion was pushing apart the bedding planes and causing more than six inches of upward movement of the fill, lifting of the slab, and causing cracking of the slab around the perimeter.

We worked together again on mines across the United States, proving everything from the source of water flowing into flooding mine workings to the absence of impact from a major tailings impoundment. I was always amazed by his skill in showing, via geochemistry, that the origin of a water stream, albeit changed by passage through other chemically potent rocks, was some other responsible party’s source and that they should do something to fix it. I was always amazed at how he proved to skeptical regulators that the chemistry of the rocks precluded environmental impact.

The second geochemist I was lucky to work with was Dr. B (not his real name). He was a large jovial fellow with a gruff humor and a ready joke. He consumed vast quantities of sushi in a vain attempt to reduce his mass. He taught me that clays love to catch onto radioactive constituents in seeping groundwater and clean up the groundwater. He seemed to be forever in his jerry-built, rented storage shed in the middle of the hot New Mexico desert passing solutions through clays and silts and sands and measuring, always measuring. But his writings won the praise of the Nuclear Regulatory Commission, and I am convinced he save the United States taxpayer by the success of his geochemical endeavors.

The third geochemist was Dr. C (not his real name). He and I had to persuade the locals that 80 feet of coal beneath a trench filled with radioactive debris would clean up seepage better than any man-made water treatment plant. To my mind the easiest proof was the quality of the water seeping from the mine workings fifty years after placement of the trench wastes. The seepage was close to clean with nary a trace of radioactivity. But try telling the locals and the regulators that. Dr. C presented them with a brilliant display of geochemical reasoning to rationalize the obvious and the future protection of groundwater quality. And his intellect and persuasive powers won the day. The trenches are still there, fifteen years later, and the seepage remains unaffected.

Consultants


It is hard to believe that any mining-related geochemistry problem, whether in exploration or environmental science, will be solved without good consultants so here is a list of some who appear on the internet—this listing also sets out the scope of services that constitute mining-related geochemistry. Please note this is a subjective selection; it is not necessarily a list of the best. These are the sites I liked, that I found interesting, and I pass them on in the hope that you will concur. If you believe you should be here, please let me know, for I probably did not find you on Google or in the Infomine database.

  • EcoMetrix in Canada has an in-house laboratory in which geoscientists test natural materials (ore, overburden) and waste products (waste rock, tailings). They specialize in acid rock drainage and metal leaching assessments, and routinely run conventional humidity cell tests, column tests that focus on specific environmental conditions, such as underwater storage, and numerous other site-specific test protocols.
  • Geochemistry Solutions in Colorado is run by Paul Taufen. Here is how he describes his services: to sharpen minerals exploration tools, complete an environmental baseline grounded in earth science, address laboratory performance, or solve a water quality issue contact him.
  • HCItascam states that John J. Mahoney has 24-years experience applying geochemical techniques to civil engineering and environmental problems—he specializes in modeling chemical reactions in groundwater systems.
  • Water Management Consultants lists Martin Williams who holds a PhD in Environmental Geochemistry and has 17 years' postdoctoral experience of in the mining-environmental and water sectors, having worked for Barrick, Newmont, Buenaventura, BHP-Billiton, Anglo American and Placer Dome.
  • In Australia, Earth Systems lists Jeff Taylor as a geochemist who has worked on environmental assessment and rehabilitation projects at operating and defunct mines in Australia, Indonesia, South Africa, Tanzania, Laos and Peru.
  • Not quite mining, but Geomatrix announces that Dr. Dawn Kaback has joined their Denver office as a Principal Geochemist and note that she has more than 27 years of experience in the environmental and energy fields, working for private industry and the federal government including the Department of Energy and the Environmental Protection Agency. My own work for these two agencies has been invaluable in representing the best interests of private sector clients.
  • Rutherford Mineral Resource Consultants in Australia at has a web site that is chockfull of interesting links, information, articles, and views relevant to geochemistry.
  • Stratus Consulting of Bolder, Colorado lists Dr. Ann Maest as an aqueous geochemist with expertise in the fate and transport of natural and anthropogenic contaminants in groundwaters, surface waters, and sediments. Her experience includes water quality impacts of hard rock mining, transport of toxics in groundwater and surface waters, and releases of toxic substances from mining and manufacturing facilities.



Books


I have not read any books on geochemistry in the past few years, so I recommend none. Like me, you can go to Amazon.com and use key words to get a long list of geochemistry books. For the record, the list I called up with geochemistry as the keyword was over 1,400 books long. With keywords mining geochemistry I pulled up over eighty books. At near $100 a book, that is an impossible amount to pay. No wonder my daughter and her husband, both Masters in geotechnical engineering working with southern California consulting firms, follow their company policies of never buying books and instead rely on the free content of the internet. That said let us proceed to do the same. Except to save you the time involved in going to Amazon.com, here are the first three books they list on geochemistry:

  • Geochemistry: An Introduction by Albrecht W. Hoffman and Francis Albarde
  • Essentials of Geochemistry by John V. Walther
  • Principles and Applications of Geochemistry by Gunter Faure.

As a post-script on geochemistry books, I quote the observation by a co-worker who notes that the world of geochemistry they inhabit is better documented in the proceedings of conferences than in the available books.

Software


Geochemical software for the exploration geochemist is available from GeoSoft at where they offer the montaj™ Geochemistry extension that enables geoscientists to effectively import, validate and analyze their surface geochemical data by providing a full range of symbol and grid display and map making functions, which include CAD tools for editing and the creation of interpretations. Click Here To Enlarge

Geochemistry software is available at the Scientific Software Group sites, SSG-Software.com and the Scientific Software Group . At these sites you will find every piece of software related to surface water and groundwater that I have ever heard of—and many more. They even have my favorites RETC and Un-Sat, the best way to model unsaturated cover performance I know of. They have old standbys available for free download, namely SUTRA, MODFLOW and PHREEQE. For those new to the field, this is their description of PHREEQE:
a USGS computer program designed to model geochemical reactions. Based on an ion pairing aqueous model, PHREEQE can calculate pH, redox potential, and mass transfer as a function of the reaction process. The composition of solutions in equilibrium with multiple phases can also be calculated in PHREEQE. The aqueous model, including elements, aqueous species, and mineral phases is exterior to the computer code and is completely user-definable.

Of course it may be simpler to go straight to the USGS site and get the software direct from the compiler. Better still go to the JChess site where you will find grouping links to sites with geochemical software, databases or information which might be of interest to any modeling geochemist.

RockWare is another source of geochemistry software including the $3,000 code The Geochemists Workbench which is a set of interactive software tools for solving problems in aqueous geochemistry, including those encountered in environmental protection and remediation, the petroleum industry, and economic geology.

“Mature” Web Sites


Time has a way of catching up with us. For example a seemingly excellent list of journals, societies, and sites related to geochemistry is to be found at the Geochemistry web links on the Cornell University website. The problem is that the last update was in September 1999 and about seventy percent of the links are now longer active with that dreaded message Page Cannot Be Found appearing. In that this is a Cornell University sponsored page, the true story is probably something like: student gets degree and moves on and site is left to mature unattended. A similar problem affects the Newsletter of the Society for Environmental Geochemistry and Health which was last updated in 2004.

Other university sites include the Johannes Gutenberg University , Mainz, Germany.

Case History – Thanks to Rescan



Here is a brief case history that illustrates the role of geochemistry in mine development (minor in this case but illustrative nonetheless). Galore Creek Valley in the Tahltan Nation Traditional lands, a remote mountainous region of northwestern British Columbia, is steep and encircled by ice-covered mountains. The area has high-value fisheries, grizzly bear, goat, and moose habitat. Rescan/ RTEC completed baseline environmental studies, including:

  • Climate Monitoring;
  • Surface Hydrology Assessment;
  • Aquatic Monitoring;
  • Soil Survey and Salvage Assessment;
  • Rock Geochemistry Characterization;
  • Vegetation Assessment;
  • Terrestrial Wildlife Assessment; and
  • Archaeological Survey.

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