Economic Geology News
Coal Miners Note: Good News for Tropical Islands - No Danger of Drowning! (24 September 2015)
The forthcoming UN climate conference causes a crescendo of reports on climate change impacts and dire warnings if a global CO2 reduction treaty should not be concluded. Forces are assembling that aim to end the extraction and burning of coal. One example of these attempts is a recent insights article in Science (Sept. 18) “King Coal and the Queen of Subsidies” that argues that the subsidies and social costs of coal surpass those of all other energy sources.
Is it forgotten that coal as abundant and cheap energy was the fundamental precondition for the increasing prosperity of industrial nations (Freese 2003) and still is for emerging economies such as China and India? Should all efforts towards “clean coal” such as carbon-capture and storage systems (CCS) come to nothing?
It is not for a geologist to argue about social and fiscal matters. But there is a geological issue that is usually raised at this kind of conferences – the drowning of Pacific islanders as the sea level rises. Who would not commiserate with these people?
Kench et al. (2015) questioned this widely accepted hypothesis by investigating Funafuti Atoll, in the tropical Pacific Ocean, that has experienced some of the highest rates of sea-level rise (∼5.1 ± 0.7 mm/yr), totalling ∼0.30 ± 0.04 m over the past 60 yr (let me note here that the rise and fall of the sea is determined by numerous local factors apart from global ones).
The authors analyzed six time slices of shoreline position over the past 118 years at 29 islands of Funafuti Atoll to determine their physical response to recent sea-level rise. They were surprised to find out that despite the magnitude of this rise, no islands have been lost, the majority have enlarged, and that there has been a 7.3% increase in net island area over the past century (A.D. 1897–2013).
Kench et al. (2015) conclude that reef islands in Funafuti continually adjust their size, shape, and position in response to variations in boundary conditions, including storms, sediment supply, as well as sea level. They suggest a positive prognosis for the future habitability of Pacific atolls.
How is growth of islands possible, in spite of rising sea-levels? Reef islands are unique landforms composed entirely of sediment produced on the surrounding coral reefs. A study in the tropical island paradise of the Maldives (Indian Ocean) quantified the major sediment-generating habitats, the abundance of sediment producers in these habitats, and the rates and size fractions of sediment generated by different taxa (Perry et al. 2015). On Vakaru island, parrotfish (85%) processing corals and Halimeda (macroalgae, 10%) were identified as the main sediment producers. Reef growth is the critical factor that provides the sand and gravel supply for maintaining the island.
Coal miners, let us rejoice that of all miseries attributed to coal, at least the threats on homes and lifes of atoll reef islanders can be eliminated from the list.
Freese, B. (2003) Coal, a human history. 336 pp. Heinemann, London.
Kench, P.S., Thompson, D., Ford, M.R., Ogawa, H. & McLean, R.F. (2015) Coral islands defy sea-level rise over the past century: Records from a central Pacific atoll. Geology 43, 515-518. http://geology.gsapubs.org/cgi/content/abstract/G36555.1v1?papetoc
Perry, C.T., Kench, P.S., O'Leary, M.J., Morgan, K.M. & Januchowski-Hartley, F. (2015) Linking reef ecology to island building: Parrotfish identified as major producers of island-building sediment in the Maldives. Geology 43, 503-506. Open Access http://geology.gsapubs.org/cgi/content/abstract/43/6/503?etoc
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Hazard and Risk – Terms that are Often Confused (26 August 2015)
Commonly, media and the public use these terms interchangeably. This confuses many important matters. I admit, however, that even my Chambers Dictionary that I consider as the English language authority, presents the terms as exchangable. We as mining professionals know better and should try to rectify any misuse.
The linguistic distinction may have originated in the world of shipping, trading and finance. Today, hazard is a dormant danger or an impending event or potential accident that poses a threat to life, health, property, economic activity or to the environment. A hazard may be known or unknown. Hazard is the danger, risk the impact or consequence if the hazard is realized. An important attribute of hazard is its probability because risk is a function of the probability or likelyhood of an event causing damage or loss. For geological hazards (e.g. landslides, extreme floods or destructive earthquakes), the natural frequency such as 3 times per 100 years is often used to describe the probability. Damage by an impending event is estimated by investigating the vulnerability of elements at risk and the consequent loss. In geotechnics, of which mining is a part, risk is often defined by the simplified equation:
R = Σ[P. Σ(V.A)]
R is risk; P is hazard expressed as probability of occurrence within a reference period (e.g. 100 years, or the design period of a building such as a tailings dam); V is the physical vulnerability of a particular element at risk (from 0 to 1) for a specific type of hazard; A is the amount or cost of the elements at risk (e.g. number of buildings, cost of buildings, number of people affected, etc.).
Typically, modern hazard and risk analysis and estimation is using advanced mathematical methods. Let us not be too deferential, however; we still remember the loss we all suffered after 2008-9, when speculative derivatives (based on the Black-Scholes Equation) blew up. Maths alone without intelligent control can be deceiving.
Risk perception by the public is an entirely different non-technical field. It is strongly recommended, however, to investigate social issues in time before a public storm breaks loose.
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Exploration Practice versus Science and Theory - Sig Muessig’s Canon for Ore Finders (22 July 2015)
Sig Muessig was a remarkably successful explorationist. In a 1998 paper, he published a summary of his views on “ore finding” that was reprinted by SEG in 2014. Look at the titles of his major rules below. In the paper, they all are further explained and I advise you strongly to acquire the full text for a proper understanding. You can download the paper for free:
I do like, as an example, his remarks explaining canon no. 1 “Exploration is not a science”:
“The aims of exploration are fundamentally at odds with those of science. Science seeks understanding, whereas exploration seeks discovery, by whatever means, with or without understanding. ... If I had to pick a basic flaw in the philosophical approach of many organizations to exploration, it would be here. Many geologists tend to ignore or disbelieve data and observations simply because they cannot explain them—no scientific cause can be established. As a result, many either walk away or they over-geologize and then walk away. Consider a classic case: the Wegener hypothesis of continental drift was derided primarily because no understandable cause could be developed, so plate tectonics lay “undiscovered” for many years.”
If you wish to delve deeper, here is the full list:
Exploration is not a science - Go with the facts, forget the theory - Try for the definitive test. -- The odds are best in the shadow of the head frame. -- Save the agonizing for mineralized trends. -- Look for ore, not mineralization. - To find an orebody, you have to drill ore holes. -- There needs to be room for the ore -- Improve it or drop it -- Do not chase spurious anomalies. -- Do not be preoccupied with explaining anomalies. -- Do not be preoccupied with path finders. -- Do not be preoccupied with stereo typed concepts -- Do not be technology driven -- Acquire first, study later -- Disregard competitor’s previous actions -- Go for the jugular. -- It’s the drill hole, stupid!
With my background in science, I might object to several of the canons (e.g. Sig’s distrust of pathfinders). But Sig has found giant ore bodies! His arguments need to be taken very seriously. And, I would add, many discussions in field camps or in board rooms might profit from throwing in one or the other of Sig’s canons!
Muessig, S. (2014) The ore finders – 18 exploration canons. SEG Newsletter 97, 17-19 (Reprint from SEG Newsletter 1998).
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Kiruna-type iron oxide-apatite (IOA) deposits – a truly innovative genetic model (24 June 2015)
Kiruna in northern Sweden is the largest iron ore producer in Europe. It is traditionally considered as the type-deposit of orthomagmatic iron ore formation related to felsic intrusions. Most scientists invoked formation of an immiscible iron oxide melt that segregated from the silicate liquid and crystallized to massive magnetite-apatite ore. Some observations seemed to favour a magmatic-extrusive ore formation or a magmatic-hydrothermal metasomatic origin similar to iron oxide-copper-gold (IOCG) deposits. Knipping et al. (2015), however, now submit convincingly that magmatic magnetite flotation is the best-fitting genetic model for Kiruna type iron ore deposits.
Froth flotation, as you all know it from ore dressing plants, uses the different wetting characteristics of ore minerals and gangue. Conditions are set so that air bubbles rising upward through a cell containing comminuted ore as an aqueous slurry attach themselves to the ore particles. Gangue sinks to the bottom while the froth is skimmed from the surface and processed into concentrate.
Recently, upward segregation of dense phases such as magnetite or sulphide liquid in silicate melt by flotation similar to the industrial process, as opposed to downward gravitational segregation, was recognized in natural systems and investigated in laboratories. Maria Edmonds (2015; free download!) describes the state of scientific understanding.
Jaayke Knipping et al. (2015) investigated the Los Colorados iron oxide-apatite (IOA) deposit in the Cretaceous Chilean iron ore belt. Iron and oxygen isotope and geochemical data (Al + Mn/Ti + V) of magnetite clearly demonstrate a magmatic origin of cores surrounded by zones of magmatic-hydrothermal character. The authors’ interpretation differentiates several stages (1) magnetite microlites segregate from dioritic melt forming suspended clouds; (2) H2O saturation induce fluid segregation; (3) rising bubbles attach themselves to magnetite crystals and form aggregates that ascend in the magma chamber; (4) concentrations of the “foam” may reach up to 37 vol% (65 wt%) magnetite; (5) the aqueous fluid component of the foam shifts the magnetite chemistry to high-T magmatic-hydrothermal characteristics; (6) the magnetite-rich foam may be trapped within the igneous system or, as at Los Colorados, intrude along faults that were active at the time. The deposit comprises ca. 350 Mt of ore (magnetite, with a gangue of actinolite, apatite, and clinopyroxene).
Let me be clear – this paper is an important innovation, or a revolution?, in our understanding of orthomagmatic ore fomation. The authors point out that the results indicate genetic relations between IOA and IOCG deposits. Reverberations of this new model may reach other deposit types. Can you think of any that may be candidates for re-interpretation?
Edmonds, M. (2015) Flotation of magmatic minerals. Geology 43, 655-656. Open Access
Knipping, J.L., Bilenker, L.D., Simon, A.C. et al. (2015) Giant Kiruna-type deposits form by efficient flotation of magmatic magnetite suspensions. Geology 43, 591-594.
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Mine Closure Experts, Take Note: Drawing Profits from Exhausted Open Pits – a Novel Approach (3 June 2015)
Recently, Younger & Mayes (reference below) proposed to use pits for gradual infilling with autochthonous organic sediments (not organic waste), which can serve as a long-term sink for atmospheric CO2. On the bottom of suitable residual opencasts, wetlands would be established. In the presence of small pit lakes, part of the vegetation might be planned as floating mats. Moderate acid rock drainage would be favourable because sulfate inhibits anaerobic decay and methane formation. Contamination dissolved in mine run-off will be retained in the freshly formed peat. Obviously, completely filling a pit with peat will take a long time, but maintenance costs should be minimal and credits for sequestered carbon can be sold. Depending on climate and the local groundwater situation, a moderate extent of water management might be needed to maintain plant growth.
In many ways, nature should profit from such sites, providing a habitat for numerous species. Likewise, local communities should enjoy their green beauty spot, as an enriched landscape of constructed ecosystems and services.
Leafing through the DMP & EPA (URL below) “Guidelines for preparing mine closure plans”, the last of four principle strategies may apply to peat production in pits: “4. Develop an alternative land use with beneficial uses other than the pre-mining land use” (page 31).
DMP & EPA (2015) Guidelines for preparing mine closure plans. 100 pp, Department of Mines and Petroleum & Environmental Protection Authority, Government of Western Australia. URL http://www.dmp.wa.gov.au/.
Younger, P.L. & Mayes, W.M. (2015) The potential use of exhausted open pit mine voids as sinks for atmospheric CO2: Insights from natural reedbeds and mine water treatment wetlands. Mine Water Environment 34, 112-120. http://dx.doi.org/10.1007/s10230-014-0293-5
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After the April 25, 2015 Earthquake in Nepal, more than ever, our help is needed! (1 May 2015)
Surely you have noticed on my home page that for many years, I support the NGO PHASE (Practical Help Achieving Self Empowerment) in improving the lives of inhabitants of remote Himalayan villages in Nepal. PHASE follows a holistic approach to development, from health care to teacher training and women’s empowerment.
After the recent earthquake, many of the project villages and other communities around are heavily hit by the destruction and their loss of all means for existence. PHASE started to help immediately after the first shock. The size of the disaster is large and so are the funds now needed.
Professional information on this earthquake is available at
Nepal April 25, 2015; Magnitude 7.8 Earthquake (USGS Earthquake pages)
Hand, E. & Priyanka, P. Pulla (2015) Nepal disaster presages a coming megaquake. Science 1 May 2015: 348 no. 6234 pp. 484-485. DOI: 10.1126/science.348.6234.484
Bilham, R. (2015) Seismology: Raising Kathmandu. Nature Geoscience 8, 582–584. doi:10.1038/ngeo2498
Article preview: “On 25 April 2015 northern Nepal shifted up to 7 m southward and Kathmandu was raised by 1 m. The causal earthquake failed to fully rupture the main fault beneath the Himalaya and hence a large earthquake appears to be inevitable in Nepal's future”
This should be interesting for many, but unfortunately, the two papers are not free for download.
For more information on PHASE, its engagement in earthquake relief and development, and for online donations to PHASE, visit