January Technical Presentation
Northland Resources Inc.'s Iron-Oxide-Copper-Gold projects Northern Fennoscandia
Northland Resources Inc.
Northland Resources Inc., a Toronto, Oslo, and Frankfurt exchange listed Canadian junior exploration company, has been exploring for iron, copper, and gold in Northern Finland and Northern Sweden since 2004. The company has secured targets in the Kolari area (Fe-Cu-Au) in Northern Finland and in Pajala (Fe-Cu), Lannavaara (Fe-Cu-Au), Saarïjärvi (Cu-Au), Paljasjärvi (Fe), and Salmivaara (Fe-Cu-Au) areas in Northern Sweden. The key targets Northland has focused in are the Hannukainen, Stora Sahavaara, and Tapuli deposits in the Kolari-Pajala region located on both sides of the border between Northern Finland and Sweden. About 25 historically known iron oxide deposits are known within this district that has been under exploration by LKAB, SGU, and Rautaruukki Oy between the 1950's and 1980's. Two of the deposits, Rautuvaara and Hannukainen at Kolari were mined for iron by Rautaruukki Oy from 1975 - 1989. In addition to iron; copper and gold were also produced from the Hannukainen deposit.
The bedrock of the Kolari-Pajala area consists of 2.44-2.05 Ga Karelian succession of rift-related greenstones and associated sedimentary units overlying metamorphosed Archean basement complex, c. 1.91-1.88 Ga Svecofennian supracrustal unit of sedimentary rocks with minor felsic volcanic rocks. Intrusive in the area are dominated by syn-orogenic, 1.89-1.86 Ga Haparanda Suite intrusions and c. 1.80 Ga late-orogenic granitoids. Minor amount of c. 2.2 Ga dolerites and c. 1.78 Ga post-orogenic granites have been detected in the eastern part of the area. The structural geology of the area is dominated by the Pajala Shear Zone (PSZ) system first described by Berthelsen and Marker (1986) who named it as Baltic-Bothnian mega-shear. The PSZ is a complex, NNE-SSW trending, about 250 km long and 10 km wide, crustal-scale shear zone system that at Pajala-Kolari area consist of several juxtaposed shear and thrust zones. The PSZ outlines the boundary between the Karelian and Norrbotten cratons and was initially formed during the amalgamation of these cratons during the Svecofennian collisional events in 1.89-1.86 Ga (e.g. Lahtinen et al. 2005). Subsequent compressional and extensional orogenic events in 1.86-1.79 Ga lead to re-activation of the PSZ structures as indicated by Northlands drillings.
All of the known occurrences are located within or immediately next to the structural lineaments of the PSZ. The mineralization style display considerable variation between and within the known Fe and Fe-Cu-Au occurrences ranging from semi-massive skarn1 hosted magnetite bodies to albitite - and granite-breccia hosted magnetite-pyrite - chalcopyrite bodies to disseminated magnetite-chalcopyrite-pyrite deposits in highly Na-K-altered mafic metavolcanic rocks. Copper and gold display background elevated values in almost all of the known occurrences, however economically interesting grades are known in only limited number of these. So far the highest public Cu-Au results are from the Laurinoja ore body at Hannukainen with best intercept containing 1.11% Cu and 0.99 g/t Au along 9.6 meter of core. The NI 43-101 compatible resource estimate of the Laurinoja magnetite body is 35.40 Million tonnes @ 37.6% Fe, 0.32% Cu, 0.170 g/t Au in measured category. Besides Cu and Au the deposits contain background elevated concentrations of Ag, Ba, Bi, Ce, Co, F, La, Ni, Mo, Se, U, and Te the ultimate metal association varying between deposit to deposit (Niiranen et al., 2007; unpublished Northland Resources Inc data).
The genetical interpretations of the Kolari-Pajala district Fe and Fe-Cu-Au deposits vary. It has been proposed that they're metamorphosed expressions of syngenetic iron formations i.e. BIFs (e.g. Frietch et al., 1995), epigenetic skarns related to the 1.89-1.86 Ga Haparanda Suite intrusions (Hiltunen, 1982), or that they belong to the broad group of epigenetic Iron oxide-Copper-Gold deposits (Niiranen et al., 2007). The data gathered during Northland's work from the Kolari and Pajala targets has revealed several features that favor IOCG model for the origin of the deposits in this area.
During the time period from 2005 to September 2007 Northland has secured total of 39,185 hectares land area on its Fe-Cu-Au targets by claiming. Exploration program in the Kolari-Pajala region has included drilling of about 280 drill holes totaling roughly 45,000 meters. Exploration campaign has also included relogging about 43,500 meters of historical drill core from various targets in the Kolari-Pajala area. As a result, Northland has been able release NI 43-101 compliant resource estimates from Stora Sahavaara and Hannukainen targets with total iron resources of 130.2 Mt in measured and 76.1 Mt in indicated, and 105.0 Mt in inferred category. Besides iron, the resources at Hannukainen include significant amounts of copper and gold. Parallel to the exploration campaign Northland has carried out metallurgical test work at its Stora Sahavaara, Hannukainen, and Tapuli targets. In addition to the Hannukainen, Stora Sahavaara, and Tapuli targets, Northland is carrying out exploration drilling in several of the Fe-Cu-Au targets in its possession at Northern Fennoscandia. For the further information of the results of current programs visit www.northlandresourcesinc.com
1Skarn used here in purely descriptive sense with no implication of the genesis of the deposit
Berthelsen, A., Marker, M., 1986. 1.9-1.8 Ga old strike-slip megashears in the Baltic shield, and their plate tectonic implications. Tectonophysics 128, 163-181.
Frietch, R., Billstr"m, K., Perhdal, J.A., 1995. Sulphur isotopes in Lowwer Proterozoic iron and sulphide ores in northern Sweden. Mineralium Deposita 30, 275-284.
Hiltunen, A., 1982. The Precambrian geology and skarn iron ores of the Rautuvaara area, northern Finland. Geological Survey of Finland Bulletin 318, 133p.
Lahtinen, R. Korja, A., Nironen, M., 2005. Paleoproterozoic tectonic evolution. In: Lehtinen, M., Nurmi, P.A., R,m", O.T. (eds), Precambrian Geology of finland Key to the Evolution of the Fennoscandian Shield. Elsevier B.V., Amsterdam, 481-532.
Niiranenen, T., Poutiainen, M., M,ntt,ri, I., 2007. Geology, geochemistry, fluid inclusion characteristics, and U Pb age studies on iron oxide Cu Au deposits in the Kolari region, northern Finland. Ore Geology Reviews 30, 75-105.
February Technical Presentation
Alternate view of Great Basin extension and implications for mineral deposit targeting
Quinton Hennigh, VP Exploration, Evolving Gold Corp, 500 Coffman St, Suite 201, Longmont, CO 80501 720-938-1945 email@example.com
Consensus among geologists is rare, yet there is near unanimity of opinion that extensional tectonism has given rise to the Great Basin and its basin and range geomorphology. That, however, is where agreement ends. Views concerning the magnitude of extension vary from a mere 10% to an extreme, >100%. A growing body of evidence indicates that the latter of these numbers may prove closer to correct.
Continental-scale seismic analysis indicates that the crust of the Great Basin is ~50% or less as thick (<30km) than surrounding continental crust (>50 km). The anomalously high geothermal gradient of the region is also suggestive of thin crust. Voluminous bi-modal volcanism, indicative of contemporaneous lower crustal and upper mantle melting, has accompanied extension from Late Eocene to present, another testament to high heat flow and significant thinning of crust.
Seismic velocity profiles across parts of the Great Basin provide evidence that the crust has been appreciably attenuated. These data also suggest that upper-crustal "blocks" are segregating as they are pulled apart from one another. Such brittle blocks appear to grade downward into highly stretched, largely ductile lower crust. Seismic sections from the Great Basin more closely resemble those from highly attenuated passive plate margins than those of any other crustal settings.
Gravity data, too, illustrate patterns of crustal block segregation. While it is acknowledged that gravity gradients in the Great Basin partially reflect contrasting material types, especially bedrock versus alluvium, it is the author's opinion that the sharp, ubiquitous gravity gradients of this region appear to define structural boundaries of upper-crustal blocks. Astonishingly, gravity gradients of the Great Basin are one to two orders of magnitude steeper than one would find in most other places on earth.
Normal fault patterns visible in all ages of rock in all parts of the Great Basin, serve as the best testament to pervasive, hyper-extension of this region. Geologic sections through many deposits illustrate ubiquitous "piano-key" normal faulting with early extensional faults lying flatter through time (i.e. fault rotation) only to be cut by successively younger, steeper normal faults. Some early fault segments can even end up rotated into positions that give them the appearance of having a reverse sense of motion. Where brittle rocks such as limestone are juxtaposed against ductile rocks such as shale, patterns similar to boundinage can develop. Patterns such as those described above can be seen at nearly every scale from mountain ranges to hand samples.
Analogue modeling can provide insight in the processes of extension and its associated structural patterns (Figure 1). Such models replicate fault patterns seen in the field and even illustrate more subtle elements of deformation that, to this point, may have been misinterpreted. Some analogue models display striking similarities to seismic sections from the Great Basin.
Although the author acknowledges that the compilation of data supporting hyper-extension is nowhere near complete, this model can serve as a worthy "working hypothesis" for exploration in the Great Basin. An appreciation of this model can help generate new ideas whether it is looking for the fault offset of a vein (Figure 2) or the dismembered parts of ore bodies. (severed half of a mining district). In fact, exploration, using the principles of this model, is precisely what is needed to test its validity.
Figure 1. Two images from an analogue model showing similarities to structural elements in the Great Basin. The top image displays a series of segregated crustal blocks. The bottom image illustrates repetitive, "piano-key" normal faulting.
Figure 2. The left image displays a vein dipping toward extensional faults. The vertical hole in the center failed to intersect the downdip projection of the vein, but the real target is to the left. A vein dips subparallel to an extensional fault in the image on the right. Again, the vertical hole failed to intersect the downdip projection of the vein. The real target lies in the footwall of the extensional fault.
March Technical Presentation
How to Use GIS with Mine and Geology Data
Willy Lynch. Mining Industry Specialist. ESRI, One International Court, Broomfield, CO 80021 firstname.lastname@example.org
GIS has evolved to be the standard tool to help the modern mining geoscientist in many aspects of their activities, from field data collection to data management, visualization, analysis, and reporting. This presentation will include a brief introduction to uses of GIS in the mining and geology industry and continue with more detailed discussions of spatial concepts and the use of ESRI's ArcGIS with mine and geology data.
An ArcGIS 9.2 compatible geologic map showing the geology of Placitas, New Mexico, USA will be utilized as an example. This map includes data from the New Mexico Bureau of Mines and Geology, USGS, USBM and was originally created as an ESRI "Sample Map" in version 8. Additional mine data created using Geosoft's Target for ArcGIS extension will also be described.p
Concepts in creating a GIS project and geodatabase for a mine and geology application will be presented including creation of vector and raster data (from GPS, Remote Sensing, digitizing sources), conversion of data (from table, shapefile, coverage, MapInfo, CAD, geodatabase and grid formats), use/creation/maintenance of metadata, and accessing data from server sources.p
Use of a simple geology data model will be briefly discussed. Additional concepts to be demonstrated include data visualization (map projections, datum's and 3D) and data analysis using the ArcGIS geoprocessing framework and model builder.
April Technical Presentation
Similarities and Contrasts: Exploring Two Sediment-Hosted Gold Districts in Nevada and the Yukon
Dorian L. (Dusty) Nicol, Executive Vice President Exploration, Yukon-Nevada Gold Corp.
Yukon-Nevada Gold Corp.'s two principal properties are the Jerritt Canyon Gold District, Nevada and the Ketza River Gold District, Yukon Territory. The two camps are similar in many respects: gold mineralization at both properties is sediment-hosted and exhibits both strong structural and strong stratigraphic control. The principal ore controlling structures at both camps are northwest and northeast trending faults. Orebodies at both camps occur where these structures intersect favorable stratigraphic horizons, with the best potential ore zones where structural intersections coincide with favorable stratigraphy.
There are, however, significant differences in the two districts: at Jerritt Canyon, the favorable stratigraphic horizons tend to be limestone and calcareous siltstones. There are few if any reliable visual guides to ore at Jerritt Canyon, though arsenic minerals (orpiment and realgar), silicification, and argillization / decarbonatization can be spatially associated (at varying degrees of proximity) with ore. At Ketza River, the favorable horizons tend to be a micritic limestone and a (possibly locally hornfelsed) argillite. Gold mineralization at Ketza is associated with massive sulfides (pyrrhotite +/- pyrite +/- arsenopyrite) and there is a clear visual guide to mineralized zones, but not to gold grade.
Geologic mapping, geochemical sampling, and geophysics have all been successful in guiding exploration at both camps. This talk will discuss similarities and contrasts that have been useful in designing and implementing successful exploration programs at Jerritt Canyon and Ketza River.
May Technical Presentation
Uranium Deposits of the Northern Powder River Basin, Wyoming and Montana, U.S.A.
Keith A. Laskowski MSc. Vice President- Bayswater Uranium Corporation
The merger of Northern Canadian Uranium Corporation (TSX-V: NCA) and Bayswater Uranium Corporation (TSX-V:BAY) in December 2007 has consolidated the ownership of historic sandstone-hosted uranium deposits of the Hullett Creek uranium district in northeast Wyoming and deep deposits discovered in the 1970s, located in southeast Montana. Bayswater, through its U.S. subsidiaries NCA Nuclear Inc. and Kilgore Gold Corp., has acquired the following properties and historical uranium resources:
|Short Tons||Pounds eU3O8||Average % eU3O8||Thickness (ft)|
|Elkhorn WY||272,608||653,000||0.080 0.15||11.08|
Historic uranium resources occur within a broad, north-south trending zone located in the northeastern Power River Basin. The zone extends more than 50 miles (80 km) along a north-south trend, extending from northeast Wyoming into southeast Montana, near Alzada. Within this trend, uranium mineralization occurs within a series of overlapping sandstone-hosted roll-front systems. Mineralization occurs in the Lower Cretaceous Fall River and the Jurassic Lakota Formations. Mineralization is present at depths ranging from near-surface to more than 1800 feet (550 m). The main project activities are currently located east and northeast of the Hauber Mine in Wyoming. The Hauber mine was mined by open-cut and underground mining methods by Homestake Mining C/orporation and produced approximately 2.76 million pounds U3O8 at an average grade of 0.23% U3O8. Bayswater holds 100% interest, subject to variable royalties, in over 58,000 acres of land holdings in 28 separate blocks of lode claims, Wyoming state leases, fee lands and areas of surface rights only. The Company is currently exploring the deposits to confirm and expand the size of the resources in order to bring them to feasibility stage and potential production.
September Newsletter Addendum
September 8, 2008
An exploration model for Wrangellia’s high grade copper deposits at Kennecott, Alaska
Price, Jason B.1, Hitzman, Murray2, Nelson, Eric2 , and Humphrey, John2,
(1) Esperanza Silver Corp. 1580 Lincoln St. #680, Denver, CO 80203, email@example.com,
(2) Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401
The high grade copper deposits at Kennecott, Alaska are among the richest known copper occurrences in the world and are located in the Wrangellia terrane. The orebodies are stratabound replacement enlarged veins that are controlled by high angle faults hosted within the structurally deformed Triassic Chitistone Limestone. The Chitistone Limestone overlies the anomalously copper-bearing, prehnite-pumpellyite metamorphosed Nikolai Greenstone (basalt). The vast majority of the known mineralization in the Kennecott district occurs within 100 m of this basalt-limestone contact.
Field, petrographic, and stable isotope data suggest that the Kennecott deposits formed in the lowermost Chitistone Limestone when a copper-bearing, oxic fluid originating from the Nikolai Greenstone mixed in favorable structural traps with a sulfide-bearing, basinal, anoxic fluid originating from the Chitistone Limestone. While the original copper-bearing Nikolai fluid was produced by dehydration reactions during prehnite-pumpellyite metamorphism at ~200ºC, the vast majority of the orthorhombic chalcocite+djurleite mineralization did not occur until fluid temperatures were ~90ºC. The driving forces for the fluid mixing are envisaged to be a mixture of gravity and tectonic pumping generated by structural imbrication during the upper Jurassic to lower Cretaceous orogeny coincident with the accretion of Wrangellia (~110 Ma).
Exploration criteria for Kennecott-type deposits include (in order of importance): proximity to a source for the copper, especially intermediate to mafic igneous rocks or, potentially, redbeds; structurally deformed, basinal, host rocks that may or may not be metamorphosed; the presence of hydrothermal dolomite veins or breccia matrices; the presence of dedolomitized haloes around fluid pathways, particularly veins and faults; strong geophysical anomalies such as gravity, resistivity, SP, and CSAMT
October Technical Presentation (double feature night)
October 6, 2008 Technical Presentation
Alteration and Mineralization at the Guelb Moghrein
Magnetite-Copper-Gold-Cobalt Deposit, Akjoujt, Mauritania.
Michael J. Kirschbaum and Murray Hitzman.
Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401,
The Guelb Moghrein (GM) mine is located near the town of Akjoujt, Mauritania, in the eastern part of the Sahara Desert. The Akjoujt area is located at a bend in the Mauritanide fold and thrust belt which extends south into Senegal and northward to Western Sahara. The Mauritanides consist of allochthonous imbricate thrust sheets directed eastward toward the West African Craton (Kolb, Sakellaris, and Meyer, 2006).
The GM mine is currently operated by First Quantum Minerals and the mine has a measured and indicated resource (not NI-43-101 compliant) of 27.3 million tons running 1.8% Cu and 1.4 g/ton gold (First Quantum Minerals, 2007). GM has been classified as an Fe oxide-copper-gold (IOCG) type deposit based on its mode of occurrence as well as the mineralization suite (Strickland and Martyn, 2001).
Mineralization occurs within a massive siderite-ankerite body containing abundant magnetite with lesser pyrrhotite and chalcopyrite. The deposit also contains arsenopyrite, cubanite, and anomalous cobalt, nickel and gold (Kolb, Sakellaris, and Meyer, 2006). The dominant gangue from the mineralized zones consists of carbonate (mainly siderite), clino-amphibole (grunerite-cummingtonite) and chlorite.
The carbonate lenses that host mineralization at GM are thoroughly brecciated and are commonly separated by strongly chloritized, interfingered schists. These schists are often mineralized and typically show a zoned alteration assemblage characterized by chlorite, clino-amphibole, and magnetite approaching the carbonate ore body.
Mineralization extends outside the ore body into the surrounding meta-basalt/gabbro, but becomes very weak. Magnetite, chalcopyrite and pyrrhotite occur in the wall rocks as extremely fine grained disseminations and also occasionally in veins. The veins occurring in the wall rocks are quartz, calcite, and quartz-calcite.
The rocks comprising the Mauritanide belt have been dated by several authors and the results have ranged from Upper to Lower Proterozoic. Recent dating of hydrothermal xenotime and monazite from the GM ore body yielded U-Pb ages of two distinct ages of hydrothermal related mineralization; 1742 and 2492 my. (Meyer et al., 2006).
Many of the rocks occurring within the Akjoujt area display similar characteristics to GM. The carbonate lenses that host the majority of mineralization at GM are not unique to the mine, and similar structures (thrust faults and shear zones) occur throughout the district. This implies that the Akjoujt area may very well be host to additional deposits similar to GM.
First Quantum Minerals Ltd., Sep. 2007, Guelb Moghrein fact sheet:
http://www.first-quantum.com/i/pdf/Guelb_Moghein_FactSheet.pdf, accessed 03/14/08.
Kolb, J., Sakellaris, G.A., and Meyer, F.M., 2006, Controls on hydrothermal Fe oxide-Cu-Au-Co mineralization at the Guelb Moghrein deposit, Akjoujt area, Mauritania: Miner Deposita, v. 41, p. 68-81.
Meyer, F.M., Kolb, J., Sakellaris, G.A., and Gerdes, A., 2006, New ages from the Mauritanides Belt: recognition of Archean IOCG mineralization at Guelb Moghrein, Mauritania: Terra Nova, v. 18, p. 345-352.
Strickland, C.D., and Martyn, J.E., 2001, The Guelb Moghrein Fe-oxide copper-gold-cobalt deposit and associated mineral occurrences, Mauritania: a geological introduction, in Porter, T.M., ed., Hydrothermal iron oxide copper-gold & related deposits: a global perspective, Adelaide, PGC Publishing, p. 275-291.
Gold Mineralization Within The Otjikoto Gold Deposit, North Central Namibia.
Elizabeth Pesce 1, Murray Hitzman 1, John Wilton 2, and Anton Lombard 2,
1Colorado School of Mines,
2TEAL Exploration & Mining.
The Otjikoto Gold deposit, controlled by Teal Exploration & Mining, is located in the Damara Orogenic Belt of north-central Namibia, approximately 300 km north of the capital Windhoek . The project is currently in the final stages of pre-feasibility, and contains 11.8 Mt indicated and 32.1 Mt inferred of 1.21 g/t Au, for a total (indicated and inferred) of 1.76 Moz of gold . Resource expansion and exploration drilling is currently in progress.
The known deposit trends northeast south-southwest along major regional lineaments and plunges to the southwest, with currently known dimensions of 500m by 3km. It is completely covered by calcrete that averages 15m in thickness throughout the drilled area. The deposit contains three distinct mineralized zones: the Upper Zone, Lower Zone, and Bottom Veins Zone.
The deposit occurs within pervasively albitized metasedimentary rocks of the Okonguari Formation, within the Northern Zone of the Damara Orogenic Belt . Main metamorphic lithologies consist of biotite schist, garnet-biotite schist, scapolite-biotite schist, and marble. Peak metamorphism produced an amphibolite facies assemblage, with metamorphism dated at approximately 550 Ma .
Two main alteration types have been recognized within the deposit: albitization and formation of amphibole/chlorite. The alteration minerals cut and replace peak metamorphic minerals and can locally destroy metamorphic foliation.
Mineralization consists of gold-bearing, thin-sheeted veins oriented parallel to the regional metamorphic foliation which contain visible gold. The veins contain variable assemblages of pyrrhotite, pyrite, magnetite, quartz, carbonate minerals, garnet, and/or native gold; some rare quartz veins with kyanite selvages can be found distally to the deposit.
Vein mineralogy varies systematical within the deposit. In general, veins deep in the system are sulfide dominant while stratigraphically higher level veins are dominated by magnetite. Veins at all levels may contain significant quartz and/or carbonate (mainly ferroan dolomite). Garnet is found in or adjacent to veins in the middle and deeper portions of the deposit.
The majority of gold mineralization is found within the veins. The highest grades are found in the pyrrhotite-bearing veins zones, particularly in veins that also contain pyrite. Gold is also found disseminated within the albitized host rocks adjacent to veins. This association was demonstrated through detailed vein sampling. Assay data show that gold grades are highest along vein edges and within thinner (<2cm) veins. Work is underway to further quantify the details of gold distribution in the deposit.
 TEAL Exploration and Mining Incorporated (2008), www.tealmining.com/tp/detailed/namibia.asp.
 TEAL Exploration and Mining Incorporated, (Unpublished Company Reports).
 Miller, R. (2004), Evolution of the Damara Orogen of South West Africa / Namibia; Geological Society of South Africa Special, Publication 11, 431-515.
Figure 1. Cross sectional diagrams of the Otjikoto Gold Deposit. Sections illustrate the distribution of gold mineralization by zone classification, mineralization zones classified by dominant mineralogy, pattern of intense alteration, and primary metamorphic lithology. Holes used to construct the diagrams were vertical, with a hole spacing of 100m.
November 2, 2008 Technical Presentation
Geology and discovery of the Cerro Jumil Gold Skarn, Morelos, Mexico
Bill Bond and Paul Bartos, Esperanza Silver Corporation
1580 Lincoln Street, Suite 680
Denver, CO 80203
The Cerro Jumil deposit, located 12 km SW of the city of Cuernavaca, represents a new grass roots discovery. The resource estimate contains 642,000 gold-equivalent ounces (measured and indicated) and 442,000 inferred gold-equivalent ounces. The geology consists of an erosional window of Cretaceous carbonate rocks intruded by a multi-phase feldspar porphyry stock.
Approaching the intrusive contact, the limestone typically shows the following progression: 1) recrystalization but retaining the original grey color, commonly with interbeds of fine to medium-grained marble, 2) medium to coarse-grained white marble (locally brecciated), 3) wollastonite and/or tremolite, both +/- garnet, and 4) garnet (+/- pyroxene). Jasperoid and retrograde alteration occur locally within the skarn zone. Within the intrusive, there is pervasive clay alteration of feldspars near the contact that diminishes
rapidly deeper into the intrusive.
Prograde exoskarn alteration appears to be controlled by pre-mineral faults, fractures, and bedding planes, forming bodies that are generally sub-parallel to the intrusive contact. Gold mineralization closely mimics the distribution of prograde metasomatism. Retrograde alteration, resulting in the development of actinolite-tremolite, epidote, calcite, clay, and jasperoid at the expense of the primary skarn minerals, tends to accompany higher grade (> 1g/t Au) values. Our interpretation is of a second, richer retrograde Au event superimposed upon initial lower grade primary mineralization. Subsequent pervasive supergene oxidation has converted all sulphide minerals to oxides; metallurgical recoveries are very good.
At present, there two partially delineated gold skarn zones (West and Southeast Zones) that parallel the intrusive contact along its contacts. A new area connecting these zones, called Cerro Calabasas, has recently been discovered. These zones have variable thicknesses of gold skarn mineralization which range from 3 meters to over 60 meters in width. At a 0.3 g/t Au-eq cut-off, the measured and indicated resource is 23.2 million tonnes, averaging 0.85 g/t Au, 0.6 g/t Ag. Exploration is continuing.
December Technical Presentation
Mineral Characterization for Geologists: Applications of Quantitative Mineralogy
Karin Hoal, Advanced Mineralogy Research Center, Colorado School of Mines, 1310 Maple St, Golden CO 80401
Characterization has been used by the mining industry for some time to identify the physical characteristics of materials such as locking and liberation for the purpose of refining extractive process flow sheets. Because the chemical and physical characteristics of an ore will impact how values are extracted from the ore material, a number of metallurgical tests such as grinding, flotation, and leach tests are routinely applied to determine the characteristics of the material. As geologists, we know that ultimately these chemical and physical parameters are a function of the mineralogy, mineral associations, and textural relationships of the material. Process mineralogy developed from the understanding that mineralogy could be used to address particular metallurgical problems that could not be resolved through standard diagnostic tests. The field of geomet has furthered the integration of mineralogy into process development. Through the quantitative identification of ore variability, geomet data sets are integrated into block models and mine planning to predict and improve project development.
The fundamental aspects of all materials in which minerals play a role is in their mineral variability and textures. Standard mineralogical identification methods such as optical microscopy, XRD, electron microprobe, etc. provide varying degrees of identification and textural and contextual information, but are not able to quantify these pieces of information over large sample sets. Recent developments in instrument hardware and software applications have resulted in advanced mineral characterization tools, which are increasingly utilized by some of the larger mining companies. The Advanced Mineralogy Research Center at Colorado School of Mines is currently the only lab to utilize the QEMSCAN system in the environment of research and applications development. For the first six months of operation, the Center was focused on five main areas: mining, energy, environmental, planetary, and materials mineral characterization. It since has become apparent these are artificial divisions, and that mineral characterization using quantitative mineralogy is a means of describing the attributes of any material. For an ore deposit, the materials of interest relate to the geological environment of formation, subsequent alteration events, structural modifications, and the spatial variability in the ore that determines deposit size, dimension, and development potential. These factors will manifest themselves during metallurgical tests and determine the way the ore breaks, leaches, or floats. In exploration, identifying the important parameters early on means reduced uncertainty and only helps in refining the extractive flow sheet. The geologist has more capabilities at his disposal, and in exploration can assess the key parameters on a laptop in the field more readily. The same mineralogical components that apply to exploration and operations will also apply to environmental management, such as identifying mineral distributions and anticipating acid release into the environment.
This talk will provide an overview of quantitative mineralogy, the AMRC facility, the main components of geomet, and the geological opportunities in integrating mineral characterization into the life cycle of a deposit.