scholarly journals Exploration Potential of Fine-Fraction Heavy Mineral Concentrates from Till Using Automated Mineralogy: A Case Study from the Izok Lake Cu–Zn–Pb–Ag VMS Deposit, Nunavut, Canada

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 310 ◽  
Author(s):  
H. Donald Lougheed ◽  
M. Beth McClenaghan ◽  
Dan Layton-Matthews ◽  
Matthew Leybourne
Keyword(s):  
Mineral Exploration ◽  
Fine Fraction ◽  
Test Site ◽  
Massive Sulfide ◽  
Heavy Mineral ◽  
Morphological Data ◽  
Indicator Mineral ◽  
Automated Mineralogy ◽  
Sediment Cover ◽  
Liberation Analysis

Exploration under thick glacial sediment cover is an important facet of modern mineral exploration in Canada and northern Europe. Till heavy mineral concentrate (HMC) indicator mineral methods are well established in exploration for diamonds, gold, and base metals in glaciated terrain. Traditional methods rely on visual examination of >250 µm HMC material, however this study applies modern automated mineralogical methods (mineral liberation analysis (MLA)) to investigate the finer (<250 µm) fraction of till HMC. Automated mineralogy of finer material allows for rapid collection of precise compositional and morphological data from a large number (10,000–100,000) of heavy mineral grains in a single sample. The Izok Lake volcanogenic massive sulfide (VMS) deposit, one of the largest undeveloped Zn–Cu resources in North America, has a well-documented fan-shaped indicator mineral dispersal train and was used as a test site for this study. Axinite, a VMS indicator mineral difficult to identify optically in HMC, is identified in till samples up to 8 km down ice. Epidote and Fe-oxide minerals are identified, with concentrations peaking proximal to mineralization. Corundum and gahnite are intergrown in till samples immediately down ice of mineralization. Till samples also contain chalcopyrite and galena up to 8 km down ice of mineralization, an increase from 1.3 km for sulfide minerals in till previously reported for coarse HMC fractions. Some of these sulfide grains occur as inclusions within chemically and physically robust mineral grains and would not be identified visually in the coarse HMC visual counts. Best practices for epoxy mineral grain mounting and abundance reporting are presented along with the automated mineralogy of till samples down ice of the deposit.

scholarly journals Automated Indicator Mineral Analysis of Fine-Grained Till Associated with the Sisson W-Mo Deposit, New Brunswick, Canada

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 103
Author(s):  
H. Donald Lougheed ◽  
M. Beth McClenaghan ◽  
Daniel Layton-Matthews ◽  
Matthew I. Leybourne ◽  
Agatha Natalie Dobosz
Keyword(s):  
Mineral Exploration ◽  
Test Site ◽  
Coarse Fraction ◽  
Heavy Mineral ◽  
Optical Methods ◽  
Morphological Data ◽  
Fine Grained ◽  
Ore Minerals ◽  
Indicator Mineral ◽  
Liberation Analysis

Exploration under thick glacial sediment cover is an important facet of modern mineral exploration in Canada and northern Europe. Till heavy mineral concentrate (HMC) indicator mineral methods are well established in exploration for diamonds, gold, and base metals in glaciated terrain. Traditional methods rely on visual examination of >250 µm HMC material. This study applies mineral liberation analysis (MLA) to investigate the finer (<250 µm) fraction of till HMC. Automated mineralogy (e.g., MLA) of finer material allows for the rapid collection of precise compositional and morphological data from a large number (10,000–100,000) of heavy mineral grains in a single sample. The Sisson W-Mo deposit has a previously documented dispersal train containing the ore minerals scheelite, wolframite, and molybdenite, along with sulfide and other accessory minerals, and was used as a test site for this study. Wolframite is identified in till samples up to 10 km down ice, whereas in previous work on the coarse fraction of till it was only identified directly overlying mineralization. Chalcopyrite and pyrite are found up to 10 km down ice, an increase over 2.5 and 5 km, respectively, achieved in previous work on the coarse fraction of the same HMC. Galena, sphalerite, arsenopyrite, and pyrrhotite are also found up to 10 km down ice after only being identified immediately overlying mineralization using the >250 µm fraction of HMC. Many of these sulfide grains are present only as inclusions in more chemically and robust minerals and would not be identified using optical methods. The extension of the wolframite dispersal train highlights the ability of MLA to identify minerals that lack distinguishing physical characteristics to aid visual identification.

scholarly journals Current Techniques and Applications of Mineral Chemistry to Mineral Exploration; Examples from Glaciated Terrain: A Review

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 59
Author(s):  
Daniel Layton-Matthews ◽  
M. Beth McClenaghan
Keyword(s):  
Mineral Exploration ◽  
Mineral Chemistry ◽  
Heavy Mineral ◽  
Optical Identification ◽  
Glacial Sediments ◽  
Volcanogenic Massive Sulfides ◽  
Kimberlite Indicator Minerals ◽  
Indicator Mineral ◽  
Automated Mineralogy ◽  
Indicator Minerals

This paper provides a summary of traditional, current, and developing exploration techniques using indicator minerals derived from glacial sediments, with a focus on Canadian case studies. The 0.25 to 2.0 mm fraction of heavy mineral concentrates (HMC) from surficial sediments is typically used for indicator mineral surveys, with the finer (0.25–0.50 mm) fraction used as the default grain size for heavy mineral concentrate studies due to the ease of concentration and separation and subsequent mineralogical identification. Similarly, commonly used indicator minerals (e.g., Kimberlite Indicator Minerals—KIMs) are well known because of ease of optical identification and their ability to survive glacial transport. Herein, we review the last 15 years of the rapidly growing application of Automated Mineralogy (e.g., MLA, QEMSCAN, TIMA, etc) to indicator mineral studies of several ore deposit types, including Ni-Cu-PGE, Volcanogenic Massive Sulfides, and a variety of porphyry systems and glacial sediments down ice of these deposits. These studies have expanded the indicator mineral species that can be applied to mineral exploration and decreased the size of the grains examined down to ~10 microns. Chemical and isotopic fertility indexes developed for bedrock can now be applied to indicator mineral grains in glacial sediments and these methods will influence the next generation of indicator mineral studies.

Advanced Identification and Quantification of In-Bearing Minerals by Scanning Electron Microscope-Based Image Analysis

2017 ◽  
Vol 23 (3) ◽  
pp. 527-537 ◽  
Author(s):  
Kai Bachmann ◽  
Max Frenzel ◽  
Joachim Krause ◽  
Jens Gutzmer
Keyword(s):  
Base Metal ◽  
Metal Sulfide ◽  
Massive Sulfide ◽  
Sulfide Ores ◽  
Grain Sizes ◽  
Mineral Assemblages ◽  
New Strategy ◽  
Automated Mineralogy ◽  
Liberation Analysis

AbstractThe identification and accurate characterization of discrete grains of rare minerals in sulfide base-metal ores is usually a cumbersome procedure due to the small grain sizes (typically <10 μm) and complex mineral assemblages in the material. In this article, a new strategy for finding and identifying indium minerals, and quantifying their composition and abundance is presented, making use of mineral liberation analysis (MLA) and electron probe microanalysis (EPMA). The method was successfully applied to polymetallic massive sulfide ores from the Neves-Corvo deposit in Portugal. The presence of roquesite and sakuraiite could be systematically detected, their concentration quantified by MLA measurements, and their identity later confirmed by EPMA analyses. Based on these results, an almost complete indium deportment could be obtained for the studied samples. This validates the approach taken, combining automated mineralogy data with electron microprobe analysis. A similar approach could be used to find minerals of other common minor and trace elements in complex base-metal sulfide ores, for example Se, Ge, Sb, or Ag, thus permitting the targeted development of resource technologies suitable for by-product recovery.

scholarly journals Indicator mineral and till geochemical signatures of the Broken Hammer Cu–Ni–PGE–Au deposit, North Range, Sudbury Structure, Ontario, Canada

2019 ◽  
Vol 20 (3) ◽  
pp. 337-356
Author(s):  
M. B. McClenaghan ◽  
D. E. Ames ◽  
L. J. Cabri
Keyword(s):  
Heavy Mineral ◽  
Laurentide Ice Sheet ◽  
Surface Zone ◽  
The North ◽  
Visual Identification ◽  
Mineral Fraction ◽  
Sudbury Structure ◽  
Platinum Group Minerals ◽  
Indicator Mineral ◽  
Liberation Analysis

The Broken Hammer Cu–Ni–PGE–Au footwall deposit in the North Range of the Sudbury Structure in Canada consists of a shallow surface zone of vein-hosted and vein stockwork-hosted mineralization within Sudbury breccia developed in the quartz monzonite Levack Gneiss Complex. The surface of the deposit consists of a 2–120 cm wide chalcopyrite vein and numerous smaller veins dominated by chalcopyrite–magnetite–millerite with trace gold, platinum group minerals, tellurides, bismuthides and selenides. The Laurentide Ice Sheet flowed southward across the region depositing a sandy till that contains abundant sperrylite (hundreds of grains), chalcopyrite, pyrite and gold in the heavy mineral fraction down-ice of mineralization. Mineral liberation analysis of the <0.25 mm heavy mineral fraction of metal-rich till identified a broader suite of PGM and sulfides than visual identification methods. The <0.063 mm fraction of till displays a strong geochemical signature of the mineralization for Pd, Pt, Au, Cu and Ag and, to a lesser extent, Bi, Te and Sn; however, geochemical signatures are not detectable as far down-ice as indicator minerals. Till sampling has not been used for exploration in the Sudbury region because of the abundant outcrop and the use of geophysical and prospecting techniques. This study demonstrates that indicator mineral and till geochemical methods are useful exploration tools for the region. The presence of sperrylite and chalcopyrite in oxidized till indicates that even thin (<1 m) highly weathered till is an effective sample medium here.

Pb-Nd-Sr Isotope Geochemistry of Metapelites from the Iberian Pyrite Belt and Its Relevance to Provenance Analysis and Mineral Exploration Surveys

2021 ◽  
Author(s):  
Filipa Luz ◽  
António Mateus ◽  
Ezequiel Ferreira ◽  
Colombo G. Tassinari ◽  
Jorge Figueiras
Keyword(s):  
Isotope Geochemistry ◽  
Mineral Exploration ◽  
Hanging Wall ◽  
Massive Sulfide ◽  
Iberian Pyrite Belt ◽  
Isotopic Signature ◽  
Sr Isotope ◽  
Provenance Analysis ◽  
Basement Rocks ◽  
World Class

Abstract The boundary in the Iberian Pyrite Belt is a world-class metallogenic district developed at the Devonian-Carboniferous boundary the Iberian Variscides that currently has seven active mines: Neves Corvo (Cu-Zn-Sn) and Aljustrel (Cu-Zn) in Portugal, and Riotinto (Cu), Las Cruces (Cu), Aguas Teñidas (Cu-Zn-Pb), Sotiel-Coronada (Cu-Zn-Pb), and La Magdalena (Cu-Zn-Pb) in Spain. The Iberian Pyrite Belt massive sulfide ores are usually hosted in the lower sections of the volcano-sedimentary complex (late Famennian to late Visean), but they also occur in the uppermost levels of the phyllite-quartzite group at the Neves Corvo deposit, stratigraphically below the volcano-sedimentary complex. A Pb-Nd-Sr isotope dataset was obtained for 98 Iberian Pyrite Belt metapelite samples (from Givetian to upper Visean), representing several phyllite-quartzite group and volcano-sedimentary complex sections that include the footwall and hanging-wall domains of ore horizons at the Neves Corvo, Aljustrel, and Lousal mines. The combination of whole-rock Nd and Sr isotopes with Th/Sc ratios shows that the siliciclastic components of Iberian Pyrite Belt metapelites are derived from older quartz-feldspathic basement rocks (–11 ≤ εNdinitial(i) ≤ –8 and (87Sr/86Sr)i up to 0.727). The younger volcano-sedimentary complex metapelites (upper Tournaisian) often comprise volcanic-derived constituents with a juvenile isotopic signature, shifting the εNdi up to +0.2. The Pb isotope data confirm that the phyllite-quartzite group and volcano-sedimentary complex successions are crustal reservoirs for metals found in the deposits. In Neves Corvo, where there is more significant Sn- and Cu-rich mineralization, the higher (206Pb/204Pb)i and (207Pb/204Pb)i values displayed by phyllite-quartzite group and lower volcano-sedimentary complex metapelites (up to 15.66 and 18.33, respectively) suggest additional contributions to the metal budget from a deeper and more radiogenic source. The proximity to Iberian Pyrite Belt massive sulfide ore systems hosted in metapelite successions is observed when (207Pb/204Pb)i &gt;15.60 and Fe2O3/TiO2 or (Cu+Zn+Pb)/Sc &gt;10. These are important criteria that should be considered in geochemical exploration surveys designed for the Iberian Pyrite Belt.

Application of indicator mineral methods to mineral exploration

2014 ◽  
Author(s):  
M B McClenaghan ◽  
A Plouffe ◽  
D Layton-Matthews
Keyword(s):  
Mineral Exploration ◽  
Indicator Mineral

scholarly journals Development of Sustainable Test Sites for Mineral Exploration and Knowledge Spillover for Industry

2020 ◽  
Vol 12 (5) ◽  
pp. 2016 ◽  
Author(s):  
Michaela Kesselring ◽  
Frank Wagner ◽  
Moritz Kirsch ◽  
Leila Ajjabou ◽  
Richard Gloaguen
Keyword(s):  
Resource Use ◽  
Physical Environment ◽  
Mineral Exploration ◽  
Test Site ◽  
Business Practices ◽  
The Social ◽  
Social And Physical Environment ◽  
Key Drivers ◽  
Environmental Measures ◽  
Social Environmental

In mineral exploration, pressure is growing to develop innovative technologies and methods with a lower impact on the social and physical environment. To assess the performance and impact of these technologies and methods, test sites are required. Embedded in the literature on sustainable development, this paper explores how social and environmental measures can be implemented in the design of test sites and what industry stake can learn from sustainable test sites. Through qualitative research, two value networks were developed, one for a sustainable test site approach and another for the existing business practice in mineral exploration. Respondents include public sector officials as well as experts in the social, environmental, business, geoscience, and industry fields. The analysis identifies key drivers for the development of socially and environmentally accepted test sites, thus drawing up actionable points for the mineral exploration industry to increase sustainability. The findings of this paper suggest that the integration of experts and partners from social, as well as environmental, sciences drives sustainability at test sites. For industry application, this results in the need to adapt the activities performed, align resource use with sustainability indicators, and also reconfigure the network of partners towards more socially and environmentally oriented business practices.

A comparison of data from airborne, semi‐airborne, and ground electromagnetic systems

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1379-1385 ◽  
Author(s):  
Richard S. Smith ◽  
A. Peter Annan ◽  
Patrick D. McGowan
Keyword(s):  
Signal To Noise Ratio ◽  
Digital Processing ◽  
Test Site ◽  
Massive Sulfide ◽  
Late Time ◽  
Signal To Noise ◽  
Waveform Data ◽  
Ground Survey ◽  
Ground System ◽  
Noise Ratio

The region around a small conductive massive sulfide body near Sudbury, Ontario, Canada, was used as a test site to compare airborne and ground electromagnetic (EM) systems with a new experimental EM system that uses a ground‐based transmitter and an airborne receiver. In this test survey, the semi‐airborne data were acquired with the transmitter loop used for the ground survey and the receiver normally used for the airborne system. At the time the data were acquired, there was no synchronization between the semi‐airborne receiver and the ground transmitter. However, subsequent digital processing of the full waveform data allowed the zero‐time position to be defined. The data could then be stacked and windowed. The ratio of the peak signal to the late‐time noise level for the airborne data is about 25:1, the semi‐airborne data shows signal‐to‐noise ratios of 500:1, while the signal‐to‐noise ratio for the ground data has a ratio of 50 000:1. This particular conductor is very close to the ground transmitter and receiver, so the signal‐to‐noise ratio for the ground system is very high. Numerical modeling shows that the marked advantage of the ground system is reduced when the conductor is deeper. However, the semi‐airborne system will generally show signal‐to‐noise intermediate between the airborne and ground systems. From an operational perspective, the semi‐airborne system has features of both the ground and airborne systems. Like the ground system, it is necessary to lay a transmitter loop on the ground; but because an aircraft is used, the semi‐airborne receiver can cover the survey area much more quickly.

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