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By T. M. Gurr

The United States is the world's leading producer of phosphate rock. In 1975 according to the U. S. Bureau of Mines' statistics, 44.3 million tonnes (48.8 million short tons) of phosphate rock were produced in the United States', which is 40.6 percent of the world's production2. The major phosphate producing areas of the United States are located in Figure 1 and the production for 1975 is listed as follows: Million Million Short Tonnes Tons Florida and North Carolina 36.9 40.7 Western States 5.3 5.8 Tennessee 2.1 2.3 All of these areas produce phosphate from deposits which are sedimentary marine in origin. Occurrences of phosphate exist throughout the United States in numerous locations that are of both igneous and sedimentary origins. However, these other phosphate occurrences vary greatly in extent and economic significance. Georgia, South Carolina, California, Texas, Arkansas, Kansas, Iowa, Alabama, Kentucky and Virginia are but a few of the states in which phosphate is thought or known to

Jan 1, 1977

By A Turek

The Lake Cinch deposit occurs in the Tazin gneisses on the footwall side of the Black Bay fault. Ore is localized by two faults, the Main Ore fault and the Cracking-stone River fault, occurring in shoots along the former and on tension fractures between the two faults. Faulting leading to the localization of the deposit is analyzed in detail and tied into the regional pattern. Pitchblende, the chief radioactive mineral, is investigated by X-ray and found to be of very small particle size. The relation-ships of U, Fe and Mn in the ore are established quantitatively, and Fe is found to bear a catalytic relation to U. The deposit is classed as belonging to Lindgren's mesothermal class. Mineralization is attributed to carbonate solutions, and the uranium is believed to have been trans-ported in the hexavalent state as the uranyl tricarbonate ion; analogy is drawn to a recently developed hydro-metallurgical technique for the production of uranium dioxide. Introduction THE Lake Cinch deposit is located in the Beaver-lodge Camp, Saskatchewan. The property was staked in 1948 and went into production in 1957

Jan 1, 1965

By T. M. Gurr

The United States is the world's leading producer of phosphate rock. In 1975 according to the US Bureau of Mines' statistics, 44.3 million tonnes (48.8 million st) of phosphate rock were produced in the United States, 1 which is 40.6% of the world's production.2 The major phosphate producing areas of the United States are located in Fig. 1 and the production for 1975 is listed as follows:

Jan 6, 1979

By T. M. Gurr

The United States is the world's leading producer of phosphate rock. In 1975 according to the US Bureau of Mines' statistics, 44.3 million tonnes (48.8 million st) of phosphate rock were produced in the United States, l which is 40.6% of the world's production.2 The major phosphate producing areas of the United States are located in [Fig. 1] and the production for 1975 is listed as follows: [ ] All of these areas produce phosphate from deposits which are of marine sedimentary origin. Occurrences of phosphate exist throughout the United States in numerous locations that are of both igneous and sedimentary origins. However, these other phosphate occurrences vary greatly in extent and economic significance. Georgia, South Carolina, California, Texas, Arkansas, Kansas, Iowa, Alabama, Kentucky, and Virginia are but a few of the states in which phosphate is thought or known to exist. The near future expansion will probably continue to be in, or near, existing producing areas, (i.e., Florida and North Carolina).

Jan 1, 1980

The main iron ore deposits of Western Australia fall into three very different geological classes, which are, in order of importance: hematite enrichment ore, pisolitic limonite ore, and sedimentary ore. These are presently (1973) being mined in the approximate proportions 20 : 2 : 1, while the equivalent proportions for reserves are, very approximately, 200 : 70 : 1. Two minor categories which mar- ginally qualify as ore are detrital material variously referred to as scree ore or canga, and potentially beneficiable iron formation. These two latter types are dealt with very briefly, and the three main categories are dis- cussed in order of economic significance. Hematite enrichment ore results from the selective replacement of a pre-existing host rock by hematite. Almost without exception, this host is cherty banded iron formation (BIF); but certain exceptions have great genetic inter- est. Ore bodies of this kind occur both in the Archaean BIFs of the Pilbara and Yilgarn Blocks and in the Proterozoic BIFs of'the Hamersley Basin. It follows from their virtual restriction to a single kind of sedimentary host that there is strong stratigraphic control over the shape of ore bodies: these may be almost flat, of dyke-like form, or of complex configuration, according to the pre-enrichment structure of the host bed. This structure was an important control over the position in which ore formed:

Jan 1, 1973

Western Australian tin deposits are similar to those of other Precam- brian terrains in that they are mainly associated with rare-metal pegmatites, in which cassiterite is found with minerals containing any or all of the elements Ta, Nb, Be, Li, Cs, Rb and the rare earths.. They differ from Phanerozoic deposits where cassiterite occurs in quartz veins, greisens, dis- seminations in granite or sulphide lodes, and is associated with minerals containing W, Mo, Bi, Sb, As, Ag, or Cu. The main tin production in Western Australia has come from the Pilbara Block where the more important tin- bearing pegmatites are related to a younger granite phase, and from Green- bushes where large albite pegmatites intrude ?Proterozoic metamorphic rocks. The more important tin deposits in the Pilbara Block, and those in the Halls Creek and Murchison Provinces, are related to granites which are richer in Si and K and poorer in Ca, Mg, Fe and Ti than 'average granite'. The tin granites tend to have higher than average contents of Sn, Rb and Li.

Jan 1, 1973

By Richard B. Berg

California was a major talc-producing State until the late 1980s when production from the deposits in the Death Valley area ceased because of a number of factors which included pressure to discontinue mining in and around Death Valley National Monument, and health concerns affecting markets for tremolitic talc. The states of Montana and Texas now account for slightly more than half of U.S. talc production. Deposits in an area encompassing southern Death Valley and extending east into the Kingston Range were formed by contact metamorphism of carbonate beds in the Precambrian Crystal Spring Formation next to Precambrian diabase sills. These deposits contain ore ranging from high-purity, fine-grained talc to platy, tremolitic talc with high brightness. Deposits of tremolitic talc and talc schist in the Silver Lake District in San Bernardino County resulted from metamorphism of Precambrian carbonate beds intruded by granitic plutons. Northeast in Esmeralda County, Nevada hydrothermal alteration related to Late Jurassic plutons caused talc replacement of Precambrian to Early Cambrian dolomite. A hydrothermal origin is also indicated for talc deposits in the lnyo Range just north of the Death Valley District where bodies of unusually pure talc occur in Paleozoic lime- stone near Jurassic granitic plutons. Talc is now mined from a deposit in the foothills of the Sierra Nevada Range southeast of Sacramento where quartz-mica schist of the Permian Calaveras Formation has been hydrothermally altered to talc. Replacement of magnesite of the Precambrian Allamoore Formation produced talc deposits mined in the Allamoore District of west Texas. This dark-gray talc of low iron content with carbon- aceous material and dolomite is ideally suited for use in ceramics where it makes a white product when fired. Small bodies of platy light-pink to white talc suitable for use as an extender in paint are also mined in this district. In the Llano District of central Texas talc has replaced impure carbonate rocks and serpentinite. All Montana talc production is from deposits in the southwestern part of the State that formed by Precambrian hydrothermal alteration of dolomitic marble. This alteration produced material with high purity that ranges from very fine-grained, massive talc to coarser grained, foliated talc. Markets include pitch control in paper, paint, cosmetics, ceramics, rubber and plastics. In southwestern and northeastern Oregon, talc has replaced serpentinite in the vicinity of Mesozoic plutons. Soapstone for carving is mined from a southwestern Oregon deposit. Deposits of similar origin occur in central and northwestern Washington.

Jan 1, 1995

By Gary B. Glass

In 1997, 92.3% or 235.7 Mt (259.8 million st) of coal produced in Wyoming came from the Wyodak coal zone in the eastern Powder River coalfield. The mined portions of the zone consist of one to three beds of coal with an aggregate thickness between 15 and 33.5 m (50 and 110 ft). The thickest expression is 61 m (200 ft). The delivered coal from this zone averages 0.33% sulfur, 5.12% ash and 19.98 MJ/kg (8,590 Btu/lb.). This coal zone occurs at or near the top of the Paleocene Fort Union Formation, which is overlain by the Eocene Wasatch Formation. There is also production from two coalbeds in the lower portion of the Wasatch at the southern end of the basin. Production of coalbed methane derived from the Wyodak coal zone is currently an estimated 289 Mm3/a (10.2 billion cu ft/year). This production is occurring west and downdip from the coal mines and is increasing each year.

Jan 1, 1998

By G. B. Glass

In 1996, 92.5% or 233 Mt (257.4 million st) of coal produced in Wyoming came from the Wyodak coal zone in the eastern Powder River Coal Field. While the mined portions of the zone consist of one to three beds of coal with an aggregate thickness between 15 and 33.5 m (50 and 110 ft), the thickest expression is 61 m (200 ft). The delivered coal from this zone averages 0.33% sulfur, 5.12% ash, and 19.98 MJ/kg (8,590 Btu/lb). This coal zone occurs at or near the top of the Paleocene Fort Union Formation, which is overlain by the Eocene Wasatch Formation. There is also production from two coal beds in the lower portion of the Wasatch at the southern end of the basin. Production of coalbed methane derived from the Wyodak coal zone is currently an estimated 10.2 billion cu ft a year. This production is occurring just west and downdip from the coal mines and is increasing each year.

Jan 1, 1998

By S. O. Reichert

The nuclear industry has made a considerable effort to reduce environmental pollution with the result that knowledge in the field of radioactive waste management is well advanced. An example of the methods used for radioactive waste disposal is provided by the Savannah River Plant (SRP) operated by E. I. du Pont de Nemours & Co. for the AEC. It occupies an area of 320 sq mi along the Savannah River downstream from Augusta Ga., and has production facilities that include a fuel preparation area, three reactor areas, two chemical separation areas (F and H), and a heavy water plant. Gaseous, Liquid and Solid Radioactive Wastes Are Handled During Disposal The primary sources of radioactive waste are the reactor and chemical separation facilities. The reactors are cooled and moderated by heavy water which, in turn, is cooled by river water in heat exchangers. This arrangement prevents irradiation of the river water so that radioactivity is not discharged into the river water except when small quantities of moderator are lost by heat exchanger leaks. Because of the high cost of heavy water, these losses must be kept to a minimum.

Jan 9, 1968

By M. M. Oosterveld

Diamonds are mined from ancient raised beach deposits in southern Namibia where complex geological controls have resulted in patchy diamond distribution, largely related to irregularities (trapsites) in the bedrock. The distribution of the number of diamonds per sample is a discrete, reverse- J shape distribution which can be characterized by two parameters. These parameters have been transformed into a Beta and Theta Contribution which can be interpreted as reflecting the 'quantity' and 'quality' of the trapsites. The relationship of statistical parameters, obtained during the sampling of an ore deposit, to the geology of the deposit is an important element of ore reserve estimation. The large-scale regional trends in the contributions have been explained in terms of the geology.

Jan 1, 1987

By Gerald L. Finfinger, Syd S. Peng

Geology is an integral part of roof control, mine design, and production operations. Yet, the importance of geology, coal/rock as an engineering construction material and its properties and behavior within the planned mine areas, in overall mine production operations has not been hilly appreciated. Of all of the engineering disciplines, mining engineers work with the most challenging construction materials. They must deal with rock materials as they exist in their natural states and design mine structures without well-known and defined properties. Further complicating the design process is the variability of the in-situ rock materials with rock types and rock properties varying widely from place-to-place. Predicting properties in advance of mining is difficult and oftentimes impossible. This is why some types of roof-control failures may suddenly occur in some areas when a single roof-control technique is consistently applied to an entire panel, section, or mine. Many roof-control techniques are primarily applicable to the geological conditions that were assumed in the development of those techniques and variations of the rocker rock properties may require modification or significant redesign of the support technology.

By William H. Langer

I spent 41 years as a geologist with the US Geological Survey (USGS) conducting geologic studies and preparing peer reviewed maps and reports describing the results of those studies. Since retiring from the USGS in 2011, I have been a consultant specializing in aggregates and other industrial minerals. Consequently, I have had the opportunity and pleasure to apply the information contained in those kinds of geologic maps and reports to real-life situations. About half of my consulting is performing due diligence for mineral resource evaluations of one type or another where resource information has been provided by the property owner. Many of those jobs necessitate that I conduct desktop studies followed by field work. I then use my information to review and comment on the written reports of others; reports variably referred to as geologic reports, resource studies, reserve analyses, and so forth. While there are many well written reports addressing geologic resource issues, I was surprised to see that there are also a significant number of so-called geologic reports that only pay cursory attention to geology. Unfortunately, that lack of rigorous geologic investigation commonly leads to erroneous conclusions. This paper addresses three such reports covering concrete sand, metallurgical gravel, and proppants (frac sand). Although all three examples are located in the Gulf Coastal Plain Province, I do not reveal the exact location of any of the properties for purposes of confidentiality. Furthermore, I have generalized the site descriptions and illustrations. However, all the descriptions faithfully define the geologic situation.

Feb 1, 2024

By Sherwin F. Kelly

THE joint meetings of the Mining Geology Committee and the Society of Economic Geologists proved to be deservedly popular, and the interesting papers drew an attendance which strained the capacity of one of the large meeting rooms.. As might be expected these days when even the Supreme Court can't keep away from the subject of gold, the discussions opened on Thursday morning with several papers devoted to questions of structural and mineralogical relationships of the deposits of this metal. The presentation of Ira B. Joralemon's paper, "Veins and Faults in the Bralorne Mine," by Reno Sales, elicited considerable discussion on the relation of mariposite to gold, and the situation of the gold deposits with respect -to the Coast Range batholith. H. V. Warren stated that lie had observed mariposite always to be associated with gold in this region, but that gold was not always associated with mariposite. He pointed out that there is a series of veins on the west side of the batholith with a different mineralogy that, because of their richness but small size could quite easily make good, small mines. John A. Dresser concurred in this, and said lie thought this region was one of great promise for the mining geologist. He also reported having found mariposite associated with gold values below commercial limits, in the Appalachian regions.

Jan 1, 1935

By D Kepert

It is the role of the exploration geologist to create wealth through the discovery, delineation and characterisation of economic mineralisation. This requires a critical depth of geological understanding.Unfortunately, the resource industry is well known for its cyclic nature. Many of the current generation of workers have only ever experienced the boom of the ‘super-cycle’ and are only just discovering the negative side to the business. For the case of the geologist and especially the exploration geologist, the magnitude of peaks and troughs are usually amplified and may become destructive to all parties. During the uptime a healthy stream of exploration good news becomes the staple diet of company releases, in particular those of junior companies attempting to bolster the share price. The geological knowledge and experience gained thus forms a significant and integral part of the value and therefore, future of a company. On the downturn it is often viewed that geologists are a luxury, an optional extra and a burden on the bottom line with companies entering a period of memory loss and myopia.Retention of geological knowledge however remains critical as projects, companies and cycles mature. Beyond exploration per se, this knowledge becomes both fundamental in de-risking and commercialising an asset (through development or divestment) and in positioning the company for cyclic or counter-cyclic opportunities.The growth and retention of this knowledge base is difficult to quantify in terms of direct value but becomes one of a successful resource companies greatest assets. At worst, its loss can lead to millions of investors’ funds wasted on missed opportunities, drilling, or poorly designed plant and mine.But the rocks are around for the longer haul and pay little notice to the vagaries of the scurrying of Man.This paper reflects on some of the authors own observations through 25 years of iron ore exploration, in why it is critical to always rigorously question the prevailing geological (mis)understanding and the technical and commercial benefits which that may bring, and looks forward to the future.CITATION:Kepert, D, 2015. Geology – the affirmative case, in Proceedings Iron Ore 2015, pp 285–298 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By M. J. McLeod, D. R. Lux, R. P. Taylor

"The Mount Douglas Granite constitutes the eastern part of the Saint George Batholith and contains the youngest, most differentiated phases of the batholith. It also contains extensive endogranitic, low-grade. Sn- W-Mo-bearing sheeted vein systems. Early phases of the Mount Douglas Granite are coarse- to medium-grained, seriate granites that represent the slowly cooled carapace of the intrusion. Late phases are medium- to fine-grained, equigranular and porphyritic granites that were accompanied by repeated and widespread fracturing of the carapace and injection of mineralizing fluids. These granites represent a highly differentiated suite with ""A "" type affinities developed in a ""within plate"" transitional to ""syn-collision"" tectonic setting. 4oAr/ 39Ar dates for biotites from the various phases indicate emplacement circa 367 Ma.The linear distribution of some phases in the Mount Douglas Granite and the systematic orientations of sheeted veins along tensional fractures indicate structural control on granite emplacement and vein distribution. This type of relatively passive endogranitic mineralization is unique in the granites of southern New Brunswick and contrasts markedly with highly fluidized systems operative elsewhere in the area. IntroductionInvestigation of Sn-W-Mo occurrences in New Brunswick has shown that most of this mineralization is associated with late, highly differentiated phases of post-orogenic (Acadian) granitoid magmatism that occurred during Devonian and Early Carboniferous time (Ruitenberg and Fyffe, 1982; Taylor et al., 1988). The polymetallic Mount Pleasant Sn-W-Mo deposit (Ruitenberg, 1967, 1972; Kooiman et al., 1986)and the Burnt Hill W deposit are two orebodies of this type in New Brunswick. Numerous smaller deposits associated with these granitoid rocks in southwestern New Brunswick have been documented in previous investigations (Ruitenberg, 1967, 1968; Ruitenberg and Fyffe, 1982; Taylor et al., 1985; Lentz, 1985)."

Jan 1, 1988

By A Madera, R Watt

The Tampakan deposit is a strongly telescoped high-sulphidation-epithermal/ porphyry deposit pair which is hosted by a sequence of probable Pliocene age subaerial andesite flows. These host units lie on the western flank of a deeply dissected andesitic stratovolcano within the northernmost portion of the Sangihe Arc in southern Mindanao. The deposit was discovered by WMC geologists in 1992 and is currently undergoing resource evaluation. Preliminary resource estimations indicate a total inferred metal content of 12 million tonnes of copper metal and 16 million ounces of gold. Using a 0.2 per cent Cu cut-off grade, the deposit has a current mineral resource of approximately 2.5 billion tonnes with an estimated grade of 0.48 per cent copper. At a higher cut-off grade of 0.5 per cent Cu, the mineral resource is approximately 900 million tonnes with an estimated grade of 0.75 per cent copper. Mineralisation is open both to the west and at depth. The Tampakan district is centrally located with respect to a 100 km wide zone of left-lateral strike-slip deformation represented by the trans-Mindanao Cotabato Fault Zone. The district is transected by several WNW-striking wrench faults which represent strands of the regional Cotabato Fault Zone. High-sulphidation epithermal mineralisation within the Tampakan deposit is strongly controlled by NNE-trending faults which lie along a dilational orientation within the Pliocene stress field associated with the Cotabato strike-slip fault zone. The mineralisation is broadly hosted by a gently-dipping, tabular zone of partial to massive silicification which displays multi-phase brecciation, acid-leaching, related vuggy porosity and which is developed within a district-scale advanced-argillic and argillic lithocap exceeding 90 km 2 in area. High-sulphidation epithermal mineralisation is associated with a silica-pyrophyllite-dickite-alunite-diaspore¦sericite alteration assemblage which is transitional downward to sericite-chlorite alteration and relict potassic biotite-chlorite-magnetite-anhydrite alteration associated with pervasively developed but weakly mineralised porphyry quartz stockwork veins. The high-sulphidation mineralisation is dominated by disseminated, vein and vug-filling enargite-bornite-digenite-chalcocite-covellite ¦ molybdenite which has overprinted an earlier phase of porphyry copper stockwork veins associated with high-level porphyritic hornblende diorite stocks. The distribution of high-sulphidation alteration and mineralisation reflects strong stratigraphic and structural controls. The high-sulphidation mineralisation covers a surface area of approximately 1.6 km by 2.0 km and forms a tabular, flat-lying to gently-dipping body between 200 and 500 metres thick. It is intersected at RL-1200 m ASL (at surface) in the northern portion of the deposit and extends down to RL-600 m ASL at the southern end. The deposit has been diamond-drill tested to a depth of 400 - 500 metres where low-grade chalcopyrite-bornite-pyrite mineralisation is hosted by pervasive quartz stockwork veins. This deep-level mineralisation represents the outer portion of a porphyry Cu system hosted by both andesite flows and the uppermost portions of high-level hornblende diorite stocks. Deep drilling to test for higher tenor porphyry Cu mineralisation is planned.

Jan 1, 1999

By C. DeLong

"The Mt. Milligan porphyry copper-gold deposits are in central British Columbia, 155 km northwest of Prince George. Mineralized outcrops and float were discovered in the Mount Milligan area by prospecting. The most recent discoveries, which utilized lithogeochemistry, were in 1983. Areas containing the outcrops and float then were investigated by geological mapping, soil and lithogeochemical sampling, ground and airborne geophysical surveys, trenching and diamond drilling. This work led to the discovery of the Mt. Milligan Main deposit in 1987 and the Southern Star deposit in 1989. Extensive diamond drilling continued until 1991 and delineated a measured and indicated resource of 299 million tonnes grading 0.45 g/t Au and 0.22 % Cu from the combined deposits.The Mt. Milligan deposits lie within the Early Mesozoic Quesnel Terrane and are hosted by porphyritic monzonite stocks and adjacent volcanic rocks of the Takla Group. The Mt. Milligan Main deposit is centred around the MBX stock and Rainbow dike, and the Southern Star deposit around the Southern Star stock.Potassic alteration is extensive within the stocks and in volcanic rocks adjacent to the MBX stock and Rainbow dike. Propylitic alteration surrounds the potassic alteration and decreases in intensuy away from the stocks. Mineralization consists mostly of pyrite, chalcopyrite, lesser magnetite, and minor bornite, molybdenite and gold.Mineralogical zoning is well-developed within the deposits. A biotite-rich subzone forms the core of the potassic alteration zone and hosts most of the copper and gold. Numerous polymetallic veins lie within the propylitic alteration zone just beyond the limit of porphyry-style copper-gold mineralization."

Jan 1, 1995

By D. K. Jorgensen

The Bullfrog and Montgomery-Shoshone deposits, near Beatty, NV, have a combined drill-indicated reserve of 15.8 Mt (17.4 million st) of ore. Average grade is 3.5 g/t (0.103 oz per st) gold and 8.2 g/t (0.24 oz per st) silver. The deposits occur in Miocene volcanic rocks that underwent large-scale movement within a detachment-faulted terrane. The principal host to gold mineralization is a strongly welded rhyolitic tuff that experienced brittle deformation during plate movement. Open space fractures and breccia were filled with quartz, calcite, and adularia accompanied by lesser pyrite, gold, and acanthite. Gold occurs as micrometer-sized particles within and adjacent to the low-angle fault and along associated listric-normal and tear faults. The Bullfrog and Montgomery-Shoshone are volcanic-hosted, detachment fault-related, epithermal quartz calcite stockwork gold deposits. Bullfrog's minable reserve is 13 Mt (14.3 million st) of ore grading 3.8 g/t (0.11 oz per st) of gold. At Montgomery-Shoshone, 2.7 Mt (3 million st) minable tons at 2.5 g/t (0.072 oz per st) are present. Preproduction stripping has begun at the Bullfrog ore body. A 7.7-kt/d (8500-stpd) carbon-in-pulp (CIP) mill is under construction. In 1990, Bond Gold expects to be producing about 6.2 t/a (200,000 oz per year) of gold.

Jan 1, 1990

By J. Beland

The Rimouski-Matapedia region is along the southwestern extension of the central Siluro-Devonian synclinorium of Gaspe Peninsula. As in Gaspe about 30,000 feet of Siluro-Devonian strata rest on a "basement" of tightly folded Ordovician rocks. The central synclinorium is divided up into two northeasterly trending belts each of which is characterized by distinctive lithologies and patterns of folding. The northwestern belt is gently to moderately folded and includes lithologies which point to a stable environment. The southeastern belt on the other hand is tightly folded and the lithologies indicate a less stable environment. A marked angular unconformity separates the basement from the Siluro-Devonian cover near the north-western margin of the northwestern belt. At the southeastern margin of the southeastern belt the relationship of cover to basement has not been as-certained because of a fault. The northwestern belt has several features significant in the search for petroleum; the Silurian strata are exposed in broad open anticlines

Jan 1, 1962