Murray W. Hitzman
Department of Geology and Geological Engineering
Colorado School of Mines
Golden, CO 80401 USA
IRON OXIDE-Cu-Au DEPOSITS: WHAT, WHERE, WHEN, AND WHY
The magnetite-apatite deposits ("Kiruna-type") and the iron oxide-Cu-Au deposits form end members of a continuum. In general the magnetite-apatite deposits form prior to the copper-bearing deposits in a particular district. While the magnetite-apatite deposits display remarkably similar styles of alteration and mineralization from district to district and throughout geologic time, the iron oxide-Cu-Au deposits are much more diverse. Deposits of this family are found in post-Archean rocks from the Early Proterozoic to the Pliocene. There appear to be three "end member" tectonic environments that account for the vast majority of these deposits: (A) intra-continental orogenic collapse; (B) intra-continental anorogenic magmatism; and (C) extension along a subduction-related continental margin. All of these environments have significant igneous activity probably related to mantle underplating, high heat flow, and source rocks (subaerial basalts, sediments, and/or magmas) that are relatively oxidized; many districts contain(ed) evaporites. While some of the magnetite-apatite deposits appear to be directly related to specific intrusions, iron oxide-Cu-Au deposits do not appear to have a direct spatial association with specific intrusions. Iron oxide-Cu-Au deposits are localized along high- to low-angle faults which are generally splays off major, crustal-scale faults. Iron oxide-Cu-Au deposits appear to have formed by: 1) significant cooling of a fluid similar to that responsible for precipitation of magnetite-apatite; 2) interaction of a fluid similar to that causing precipitation of magnetite-apatite with a cooler, copper-, gold-, and relatively sulfate-rich fluid of meteoric or "basinal" derivation; or 3) a fluid unrelated to that responsible for the magnetite-apatite systems but which is also oxidized and saline, though probably cooler and sulfate-bearing. The variability of potential ore fluids, together with the diverse rock types in which these deposits are located, results in the wide variety of deposit styles and mineralogies.
Richard W. Hutchinson
Charles F. Fogarty Professor (Emeritus) of Economic Geology
Colorado School of Mines
A Century of Evolution in Knowledge and Genetic Understanding of Massive Sulfide Deposits
Current knowledge of massive base metal sulfide deposits has evolved mainly during the last century. It began with descriptive information based on field mapping and observation of a few, then increasing numbers of deposits. The development and proliferation of new analytical and observational laboratory techniques, beginning about fifty years ago, accompanied by the revolutionary introduction of new global tectonic concepts and consequent studies of their sea floor generative systems then led to our modern understandings. Philosopher George Santayana's admonishment that "those who do not read history are condemned to relive it" suggests that a review of this evolution in thinking may aid in avoiding repetition of some misinterpretations and oversights.
Prehistoric and ancient work on VHMS deposits at modern day Ergani in central Turkey and Cyprus, and mediaeval mining at Rammelsberg in Germany and Falun in Sweden focused on production; there is little indication of thinking about how the ores originated. In 1894 however, a German geologist, A.W. Stelzner, studied samples of Broken Hill ores in Freiberg and - - "was convinced that they represented an ore bed which had been formed simultaneously with the surrounding country rock, hence was of sedimentary origin". In the early decades of the century, Japanese geologists too, concluded from mapping and field relationships, that the Kuroko deposits of northern Honshu had formed on the sea floor although the generative processes were not understood. Interestingly, these earliest genetic interpretations were closer to current understandings than succeeding ones, probably due to the younger age and minor metamorphism of the Japanese ores, and consequently less complex field relationships.
Then followed a tidal wave of epigeneticism prompted by Lindgren's interpretations about certain deposits of the western USA, which were vastly and inappropriately overextended in application to virtually all metalliferous ores. Here history provides a useful lesson. Unlike elections, truth in science is not decided by popular vote and its pursuit is not promoted by a bandwagon approach! Yet some field relationships of older VMS deposits in the early decades too, indicated late sulfide emplacement, apparently long after formation of their host rocks. For example, although apparently cut by a late-Precambrian diabase dyke, sulfides in the Archean volcanic-hosted Horne ore body at Noranda clearly penetrated the dyke's walls as described by Suffel in a 1935 Economic Geology paper, clearly proving a latest Precambrian age of this great ore body. Virtually all VMS deposits were thus classified as epigenetic replacements through the century's middle decades.
These circumstances too, are historically relevant to current studies, although too often overlooked!. All sea floor-generated deposits must, perforce, have undergone varying types, degrees and episodes of post-depositional metamorphism. This revises, complicates, obscures or even totally obliterates not only primary field relationships, but also primary mineralogy, mineral chemistry, textures, and paragenetic relationships, as well as fluid inclusion and isotopic signatures. As W.S. Gilbert wrote in HMS Pinafore, "Things are seldom what they seem - -"! What then do we observe when we study and measure these parameters, and how reliable are interpretations based on them? The common basic assumption that they reflect the primary genetic environment is too simple, variably unreliable and flawed. A multistage, multi-process genetic history must be considered not only for VMS ores, but also for other ancient deposits, including some greenstone-hosted gold lodes.
It is relevant, albeit difficult for today's researchers to appreciate, that until mid-century, the reflecting ore microscope and wet chemical analyses remained the main investigative laboratory procedures. Nevertheless, in the 1950's the early-century, "syn-sedimentary" genetic concepts were resurrected by a few thoughtful workers, notably Haddon King and colleagues at Broken Hill, and Christoffer Oftedahl in Norway. Although initially rejected by many , the applicability of these to field relationships, many of which they were found to explain better than did epigenetic concepts, was hotly argued.
In the early 1950's Texas Gulf Sulfur geologists W. Holyk and L. Miller recognized the close spatial association between felsic fragmental and pyroclastic volcanic rocks and orebodies in the Bathurst District of northern New Brunswick. They subsequently applied the relationship in exploration of the Abitibi greenstone belt near Timmins, Ontario, leading to discovery of the Kidd Creek deposit. Then followed well documented field relationships that cast serious doubt on the epigenetic hypothesis. These included sharp contacts between massive sulfide and wall rocks, jig saw puzzle-like fits amongst angular and essentially barren wall rock inclusions within massive sulfide, and conglomeratic ores consisting of barren rock cobbles and pebbles in massive sulfide matrix. Stratigraphic relationships repeatedly revealed fresh or only slightly altered, and ferruginous chemical sedimentary rocks stratigraphically above massive ore but highly altered ones below. Repeated and consistent metal / mineral zoning showed Cu-rich ore in the stratigraphic footwall below higher Zn-Pb-rich ore, even in deformed, steeply dipping strata. Although not all present in all deposits, collectively these relationships were sufficiently common to constitute compelling evidence against epigenesis. In Cyprus, again where deformation and metamorphism were minimal, ore bodies were cut by mafic dykes that fed overlying pillowed basalts, clearly confirming syn-basaltic ore deposition on the sea floor, although the generative process remained unknown and enigmatic - certainly to this writer! Final acceptance of the syn-sedimentary concept came when its application in the Noranda District led to a series of discoveries in the 1960's - 70's; first, the small Vauze ore body by R. Edwards and his colleagues for ConZinc Corp., then in impressive succession over some dozen years, the important, larger and rich Lake Dufault (Norbec), Millenbach, Corbet and Ansil deposits by Falconbridge Copper and its excellent geological staff.
Then rapidly followed first, the truly revolutionary advent of new global tectonic concepts, and second, oceanographic systems for study, then sampling of the ocean floor, both accompanied by development of a myriad of new, diverse, ever more sensitive and accurate laboratory techniques for detailed study of both ancient massive sulfide ores and their modern sea floor analogues. The first two allowed recognition, distinction, then sampling of the differing sea floor tectono-stratigraphic environments where these deposits form. This led in turn, to improved classification of the differing types of both volcanic- (VHMS) and sedimentary-hosted (SEDEX) massive sulfide deposits. The sea floor studies identified and measured the physico-chemical parameters of their generative hydrothermal processes. The laboratory techniques applied to samples of both sea floor and ancient deposits have provided extensive broad and detailed data that is further applicable to understanding the complete nature of the generative ore-forming systems and their affect on the rocks in which they are active. These data are further applicable to, thus aid in exploration for ancient deposits.
The presence and importance of extensive wall rock alteration in close spatial, therefore presumably genetic association with the sulfide bodies too, was early recognized. Dalmatianite, or "spotted dog" alteration, was successfully used as indicating nearby ore by earliest prospectors in the Noranda district in the 1930's. Peter Price, then Noranda's senior geologist, described chloritization, sericitization and silicification at Horne Mine in 1948. Adequate understanding of the mineralogical compositions and generation of these however, awaited much later development of modern XRD and microanalytical techniques. Until the 1960's chlorites were optically assignable to only a few varieties with little knowledge of their mineral chemistry, and no distinction was possible between paragonitic and potassic sericite. The important sequential and progressive chemical changes through removal and exchange of alkaline, alkaline earth elements and ferrous iron, together with the immobility of alumina and other components, all during alteration accompanying sea floor hydrothermal activity that emplaced the sulfides were therefore simply not previously understandable.
Current understandings of massive sulfide deposits thus are not due alone to our impressive modern scientific expertise and technology. Rather they reflect a long succession of changing, sometimes retrogressing, but mainly progressive new interpretations. These in turn, stem fundamentally from observed field relationships, extensive and thorough sampling of both ancient and sea floor deposits, followed up by detailed studies of the samples using the wide variety of modern microanalytical and laboratory techniques. And, although generally overlooked, huge advances in modern transportation, data processing and communications since World War II have materially aided all scientific understandings.
What then, remains poorly understood, requiring further investigation? The recent studies have elucidated shared characteristics and subtle differences amongst differing varieties of VHMS and SEDEX ores, establishing "linkages" throughout the broad spectrum of sea floor-formed massive sulfide deposits. As yet unevaluated however, are possible comparable linkages between carbonate-hosted SEDEX deposits such as Red Dog, Reocin or the Irish deposits, and carbonate-hosted MVT and certain skarn ores. Finally, only sites of sulfide deposition can be adequately sampled in both sea floor and ancient deposits. Full understanding of ore generation however, requires knowledge not only of ore deposition - the "end-product" - but also of the source and mobilization of the ore components and their transporting fluids. These aspects are "remote" from the depositional sites, therefore not readily sampled or measured, thus must be investigated by interpretive approaches. They are commonly overlooked because of their consequent uncertainty, and poor definability. Yet future research must attempt to provide at least reasonably permissive, thus acceptable explanations of these important aspects.
In summary, current understandings of massive sulfide deposits are not due alone to impressive modern scientific expertise and technology. Rather they result from a long succession of studies and changing, sometimes retrogressing but mainly improving genetic hypotheses. Their important basic, albeit broad characteristics had been recognized and correctly interpreted genetically by about 1970, fundamentally based on observed field relationships from thorough observation, sampling and study of ancient deposits. Moreover, effective exploration approaches had been developed based on these understandings which, greatly aided by new geophysical and geochemical techniques, had led to discovery of many important deposits, including perhaps the world's greatest ones, Kidd Creek and Neves Corvo. New geo-scientific knowledge and technology have subsequently greatly elucidated the previously undetermined, more detailed generative sea floor hydrothermal processes that form these ores. From an explorationist's viewpoint however, it is doubtful that these new understandings, albeit scientifically important, have yet significantly improved the productivity and cost effectiveness of exploration through new discoveries. It remains to be seen whether they will do so in future.
The Greens Creek massive sulfide deposit, southeastern Alaska
Cliff D. Taylor, U.S. Geological Survey, Box 25046 Federal Center, MS-973, Denver, CO 80225-0046, USA. firstname.lastname@example.org.
Greens Creek is an unusual polymetallic mafic-ultramafic igneous-, platform carbonate-, and clastic sediment-hosted deposit of 24.2 million tonnes (13.9 % Zn, 5.1 % Pb, 0.17 oz/t Au, and 21.4 oz/t Ag at zero cut-off) that is located on the northern end of Admiralty Island, 29 kms south of Juneau, Alaska. The deposit is hosted in a 1-km-thick, rift-fill volcano-sedimentary succession of late Triassic age that comprises the eastern margin of the allochthonous Alexander terrane. The orebody consists of a single lens that sits at the contact between a stratigraphic footwall of mafic phyllites and volumetrically minor platform carbonate rocks, and hanging wall of graphitic, pyritic, argillites. 220 Ma hypabyssal mafic-ultramafic sills and intrusions are present in the footwall and around the mine and are thought to be the heat and possibly a metal source for mineralization. Age relationships suggest that mineralization occurred during shale sedimentation by replacement of, and inflation beneath, the accumulating shale cap (Taylor et al., 1999).
Alteration petrography and geochemistry at Greens Creek suggest a very large, diffuse, and roughly symmetrical alteration envelope extending beyond the deepest drillholes studied (~170 m). Proximal to distal alteration is characterized by quartz-sericite, to sericite-carbonate (+-chlorite-quartz), to chlorite-sericite-carbonate (+-quartz), to chlorite-carbonate (+-quartz). Sericites and chlorites exhibit Cr and Ba, and Fe/Mg zonation with distance from ore, respectively. Carbonate zonation varies from dolomite in ore, to Fe-dolomite, to Mn-rich dolomite, to calcite outside of the envelope. Minor celsian is co-extensive with the Ba-rich sericite and magnesite occurs with the Fe-dolomite.
Greens Creek consists of three main orebodies, the East, West, and Southwest, and three extensions. The Klaus thrust fault separates the East and West orebodies and the Maki fault, a major, near-vertical, strike-slip fault, cuts the property in two. The Southwest orebody extends from the West/Northwest orebody in a complex helical fold that plunges 25o to the southwest. Continuity of the orebodies is interrupted by numerous thrusts and strike-slip faults on and parallel to the Klaus and Maki faults. Multiple phases of folding have further modified the deposit morphology. However, with few exceptions the ore horizon is traceable along the phyllite-argillite contact throughout the mine. Restoration of 600 m movement along the Maki and 200 m movement along the Klaus (P. Lindberg, unpublished company reports) results in a single orebody with a thickened central core in the West/Northwest orebody, which thins to the north, east, and south.
Ore lithologies fall into two groups; massive sulfide ores and semi-massive or disseminated sulfide gangue-rich "white" ores. The massive ores contain greater than 50% sulfides and are fine- to very-fine-grained. All the massive ores have subordinate quartz, dolomite, sericite, fuchsite, and barite. The white ores contain less than 50% sulfides. They commonly contain base metal and spectacular precious metal enrichments. There are three types; white carbonate ore and white siliceous ore are most common, and white baritic ore. All the ore types include sub-types that are modified by the presence of veins, breccias, and gouge or rubble zones produced during faulting or folding. Veining due to remobilization and recrystallization during metamorphism can result in spectacular enrichments of free gold and a variety of Ag-sulfosalt minerals. Breccias appear to be both syndepositional, produced by slumping of the massive sulfides and the underlying host rocks, and tectonic, produced during deformation. Solution brecciation may also have occurred in the white carbonate ores.
Drill intercepts in the thickest portion of the Northwest orebody outline a large, cohesive block of massive fine-grained pyritic ore with the highest and most consistent copper grades (assays to 4% Cu) in the mine. High Cu is accompanied by high Au, and lower Zn, Pb, and Ag. Polished thin sections reveal higher than average amounts of primary and secondary remobilized chalcopyrite, arsenian pyrite and free gold. This proximal assemblage is centered over a particularly thick footwall sequence of highly siliceous phyllites. Laterally, the first ore types encountered above the footwall are white siliceous ores followed by white carbonate ores and white barite ores. White ores are overlain by massive fine-grained pyritic ores that change upwards and outwards towards lower Cu-Au grades. Ores change gradationally into increasingly higher grade Zn-Pb-Ag- (Au)-rich massive fine-grained base-metal-rich ores towards the argillite hanging wall and the margins of the deposit. Distal ore is often are characterized by carbonate- and barite-rich white ores against footwall phyllites which grade into massive fine grained base-metal-rich ores towards the hanging wall. This progression of ore types is the pattern most commonly seen throughout the mine.
Roughly 30% of the Greens Creek ores retain primary mineralogy and textures. Framboidal, colliform, dendritic, and "spongy" textured pyrite are commonly intergrown with base metal sulfides and sulfosalts. Primary assemblages include sphalerite, galena, tetrahedrite, chalcopyrite, free gold and a variety of Pb-Sb-As (-Hg-Tl) sulfosalts. Recrystallization results in much coarser textures and the formation and/or remobilization of secondary, precious-metal-enriched minerals. Secondary minerals are present as matrix to pyrite euhedra and in late fractures and veinlets. Secondary mineralogy includes chalcopyrite, sphalerite (low iron), galena, free gold, electrum, tetrahedrite (Sb-rich), pyrargerite, and a host of other sulfosalt minerals. A subset of the primary textured pyritic ores has trace to 50% pyrite recrystallized or replaced by arsenian pyrite and arsenopyrite.
Sulfide sulfur is strongly 34S-depleted and defines a 34S range of -38 to 2â. Pyrite values span the range and values from chalcopyrite, sphalerite, and galena cluster tightly between -11 and -16â. Shifts in chalcopyrite-sphalerite-galena median 34S values are consistent with equilibrium isotopic fractionations; sphalerite-galena mineral pairs indicate a formation temperature of ~300o C. Primary textured sulfides are generally more 34S-depleted than recrystallized or remobilized sulfides, and the most 34S-enriched values occur in the smaller and more distally located orebodies. On a deposit scale the most 34S-enriched sulfides are near the footwall igneous rocks and white siliceous ores. The progression towards 34S-depleted sulfides roughly follows the ore paragenesis from white ores against the footwall, to massive pyritic, to massive base-metal-rich ores against the hanging wall. Pyrite 34S values in the overlying shales exhibit a wide range of values from -29.0 to 1.1â. Sulfate 34S values fall between 9 and 22â, consistent with global values for Triassic evaporites. Consistent with ore mineral paragenetic relationships, the unimodal distribution of both ore stage pyrite and base metal sulfide sulfur isotope values suggests a single fluid supply of sulfur from two main sources. The data suggest input of heavy sulfur from the mafic-ultramafic footwall igneous rocks and a dominant source of light sulfur from biogenically reduced seawater sulfate present in pore water and/or in diagenetic pyrite in the hanging wall shales.
The current genetic model suggests onset of rifting and formation of precious-metal-rich silica-barite-carbonate white ores at low temperature in a shallow, sub-aqueous setting, probably a thin carbonate shelf on the flanks of an arc. As rifting intensified, the shelf was down-faulted and isolated as a graben. Shale sedimentation inundated the hydrothermal system, eventually forming a cap. Ore deposition continued at higher temperature by inflation and diagenetic replacement at the base of the shale cap.
METALLOGENIC TIES: WEST AFRICAN AND GUIANA CRATONS
by Fred Barnard, Mining Evaluation Profiles, Golden, Colo.
Geologic and metallogenic similarities between the West African
and Guiana cratons have long been recognized. The cratons are
of comparable size: 0.7 to 1.0 million sq km, if areas of post-1.0
B.Y. non-metamorphosed sediments are excluded. Both are located
in tropical regions, both include parts of several countries,
and both are among the lesser-studied of the Earth's large Precambrian
cratons. It is obvious that the two cratons share many features
in their pre-Drift history, and many matches exist between individual
Precambrian structural or lithostratigraphic features on opposite
sides of the Atlantic. However, similtaneous matching of several
features is more tenuous, suggesting that significant dislocations
occurred during or after separation of the two continents.
Mineral deposits of Precambian age in the two regions show a number of similarities in their genesis, distribution, and relative importance:
(Pastoral, et al.)
Mineral deposits of Phanerozoic age (bauxite, mineral sands, phosphate) do not show such close trans-Atlantic similarities.
Systematic comparison of the mineralization styles in the two cratons leaves ample scope for future discoveries in each, especially in the Paleo-Proterozoic greenstone terranes (Birimian of West Africa and Pastora-Barama-Paramaca of the Guiana Craton).
Industrial Minerals: Much Used, Little Noticed
David M. Abbott, Jr., Consulting Geologist
Industrial minerals and the products made from them surround us but we generally fail to recognize them. The typical bathroom contains a plethora of industrial minerals. Porcelain and tile products are fairly obvious. But there also are a variety of abrasives, numerous fillers and extenders, types of glass, clays as coaters and fillers, even in the toilet paper, and even in the cosmetics. We learned how kaopectate worked in clay mineralogy. This talk presents an overview of some of the many types of industrial minerals that we use daily together with some examples of deposits and processing. Aggregates and other construction minerals and materials are volumetrically among the most important industrial minerals. Yet most people object to the clay pits, sand and gravel quarries, or crushed stone quarries that one encounters around the Denver metro and other areas. The difficulties in obtaining and maintaining operating permits for such operations and the resulting change in the concept of place value will also be discussed. We need industrial mineral products and exhausted pits and quarries can become extremely valuable real estate. Political decisions made today can have significant impacts on the cost of living tomorrow. The part of the talk is aimed at a general audience. Bring your spouse, friends, older children, etc.
The talk will also take a short look at the standard (CMMI) mineral resources and reserves classification scheme from the industrial minerals perspective, which highlight undisclosed biases inherent in the system. Specifically, standard classification schemes view assurance of deposit continuity, which is based on sample spacing, as the most critical factor in determining the whether inferred, indicated, or measured resources or probable or proven ore exist. Marketing, which is far more critical in determining the economic potential of most industrial mineral deposits, is merely one of many modifying factors considered in converting indicated and measured resources into probable and proven reserves. Recognition of this bias is important not only for industrial minerals but for metals as well. The underlying assumption that what is produced can always be sold into the market may not be true, or at least market affect must be recognized in some cases.
THE GEOLOGY AND PGE MINERALIZATION OF THE PENIKAT INTRUSION
AND PORTIMO COMPLEX, NORTH CENTRAL FINLAND
Craig J. Nelsen, Senior Vice President Exploration, Gold Fields Ltd
Gold Fields Limited (earning 51% and operator) and Outokumpu
Mining Oy formed the Arctic Platinum Partnership (APP) to explore
for and develop Platinum Group Element (PGE) deposits within a
9,500 sq. km. area in north central Finland. The Arctic Platinum
project is underlain by Archean gneisses and early Proterozoic,
mafic-ultramafic layered intrusions and volcanosedimentary rocks.
The layered intrusions are localized along a regional crustal
contact between Early Proterozoic greenstone belts and Archean
rocks, including gneisses and granites and older greenstone belts.
Exploration completed over the past several decades by Outokumpu
Oy has identified a number of Cu-Ni-PGE-Au occurrences within
several, early Proterozoic (2.4 Ga ) mafic-ultramafic intrusions,
including the Penikat Intrusion and Portimo Complex. PGE mineralization
is typically associated with sulfides and form three main deposit
types, including (i)"reef-type" PGE (and associated
"pot-hole") mineralization, (ii) Marginal Series PGE
mineralization consisting of disseminated and locally semi-massive
sulfide mineralization near the lower contact of the intrusion,
and (iii) "offset-type" mineralization as copper-dominated,
massive sulfide mineralization or PGE-dominated, disseminated
sulfide mineralization within basement rocks.
The Penikat Intrusion is a 23-kilometer long layered sequence
hosting 5 megacyclic units (5 distinct magma injections). Within
this layered sequence, three PGE reefs have been identified: (i)
the SJ, (ii) PV, and (iii) AP reefs, at the contact between the
various megacyclic units. Diamond drilling along the 23 kilometer
strike length has returned numerous intersections assaying up
to several hundred grams per tonne PGE (Pt+Pd+Au) over widths
ranging from several centimeters to several meters. This PGE mineralization,
in terms of host rock and distribution of grades, is similar to
that of the Merensky Reef in the Bushveld Complex, South Africa,
and the J-M Reef in the Stillwater Complex, Montana.
The Portimo Complex is host to a number of fault-dislocated mafic intrusive bodies hosting occurrences known as Konttijarvi, Ahmavaara and Kilvenjarvi. The Cu-Ni-PGE-Au mineralization within the Portimo Complex is host to all three distinctive deposit types. The most important type being the disseminated Marginal Series where APP has announced an updated (July 24, 2001) resource at Konttijarvi and Ahmavaara of 6.0 million ounces 2PGE+Au, contained in 117.5 million tonnes grading 0.28 g/t Pt, 1.19 g/t Pd, 0.11 g/t Au (1.6 g/t 2PGE+Au), and 0.08% Ni and 0.19%Cu. APP is presently completing a Feasibility Study on mining and processing alternatives that should be completed in the third quarter of 2002.
Stanley Dempsey, Chairman and Chief Executive Officer
and Donald Baker, Vice President Corporate Development
Royal Gold, Inc
Royal Gold's European Exploration Program
Royal Gold is the largest U.S.- based precious metals royalty firm. One of the ways it creates royalties is through exploration and advancement of projects, with subsequent farm-outs to majors while retaining a royalty interest.
Royal Gold's exploration programs have been centered on the Great Basin states, the Union Pacific land grant, and Central and Eastern Europe. These programs have been reduced substantially during the past few years, but Royal Gold remains active in Greece and Bulgaria. Royal Gold operates with a very small staff, utilizing consultants and outside contractors for all of its work. It focuses on properties of high geologic potential and perceived low title and permitting risk. Royal Gold attempts to carefully define its objectives, and is not afraid to drop a property if it looks like commercial success is unlikely.
This presentation will focus on Royal Gold's approach to working abroad, and specifically, on the Milos project in Greece. Our analysis of foreign opportunities includes attention to issues involving security of tenure, transparency and personal security. Royal Gold prefers to focus on opportunities within major precious metal provinces or on targets with potential for very rapid advancement. We also prefer working with capable explorers/producers in politically reliable places who maintain high standards of practice and conduct. We feel it is imperative, especially as a small company, to work with a local partner and to over-emphasize public relations and community relations from the onset of project activities.
Graham Farquharson, SEG Thayer Lindsley lecturer
Red Flags Over Busang
For three and a half years the world watched as the Busang property of Bre-X Minerals Ltd. rapidly grew into one of the largest gold deposits ever discovered. In April 1997 an independent audit quickly revealed that Busang was the site of the largest fraud that the global mining industry has ever known. What were the red flags flying over Busang that experienced mining industry observers and investors failed to notice for so long?
David M. Abbott, Jr., Consulting Geologist
"There's glory for you": definition-related problems between the CMMI, SEC, and USGS mineral reserve and resource classification systems
"There's glory for you" is the beginning of a famous quotation from Through the Looking Glass in which Humpty Dumpty states that "glory" means "a nice knock-down argument." Alice objects that "glory" doesn't mean that and Humpty Dumpty declares that it is all a matter of who's in charge.
Somewhat like Humpty Dumpty, the definitions of "reserves," "resources," "measured," and "indicated" mean different things in the mineral reserve and resource classification systems adopted by the Council of Mining & Metallurgical Institutions (CMMI), which includes the Society for Mining, Metallurgy, & Exploration (SME); the US Securities & Exchange Commission (SEC); and the US Geological Survey (USGS).
"Measured resource" in the CMMI system is not the same as "measured resource" in the USGS system because each system is answering a different question about mineral resources. The CMMI focuses on the detailed geologic delineation of specific deposits today while the USGS focuses on mineral resource needs decades into the future. "Proven (measured) reserve" means something else to the SEC, which doesn't recognize the term "resource" at all.
This problem is further complicated because the technical definitions of "reserves" and "resources" are opposite of those used in everyday English. Are "reserves" quantities held for future use or available for current use? Whether mineral reserves are separate from or a subset of mineral resources is another point of confusion within the CMMI system. Mineral resources estimate the in situ deposit while mineral reserves are adjusted for profitable mining including dilution, deletion, and processing losses.
Finally, although all classification systems agree that there is a "blue sky line" at the boundary between having sufficient information to reasonably estimate tonnage and grade on the one hand and lacking sufficient information for reasonable estimates on the other, they disagree over the placement of that line. Because these terms are part of securities regulation, failure to appreciate and carefully distinguish the differences between the differing meanings may lead to unwanted litigation.
Power Point file in PDF format from thepresentation that graphically illustrates definition-related problems between the CMMI, SEC, and USGS mineral reserve and resource classification systems