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By Richard W. Brummett, Robert L. Dubms

Located some 180 miles east of Los Angeles in Riverside County, California, the Eagle Mountain mine supplies iron ore concentrates for the Kaiser Steel Corporation steel plant in Fontana, California, and for export to Japan. Although the deposits were first discovered in the early 1890's, no production was realized from the area until 1948 when Kaiser Steel Corporation commenced operations. A part of the large Basin and Range province, the Eagle Mountain area's geologic column comprises a thick series of metasediments resting on Precambrian gneisses and schists that have been intruded by sill-like masses of porphyritic quartz monzonite. The metasediments are composed of three quartzite units that are separated by a schistose meta-arkose and by two ore zones. They have been folded into a large east-west trending anticlinal structure that extends completely across the Eagle Mountains. The iron ore deposits occur in two well-defined horizons in the metasedimentary series, and they are found only along the north limb of the major anticline. Host rocks for the ore zones were a series of limestones and dolomites with associated quartzites. Magnetite plus pyrite comprised the primary mineralization that formed many replacement lenses and stringers of ore within the ore zones. The primary ore has been oxidized to hematite and goethite in a broad zone at higher elevations in the deposits. Hydrothermal alteration formed actinolite- tremolite granofels, local phlogopite, and minor tourmaline in the ore zones. This alteration and the ore deposition seem related to the same magmatic event that formed the porphyritic quartz monzonite intrusion

Jan 1, 1968

By John H. Schilling

The Gabbs magnesite-brucite deposit is unique in size and is one of two magnesite deposits being exploited in the United States. It is near the town of Gabbs, which is one hundred miles southeast of Reno, in west-central Nevada. The brucite was discovered in 1927; the magnesite was found while exploring the brucite. During World War II, more than 80,000 tons of magnesium metal was produced from about 900,000 tons of magnesite ore mined from these deposits. An additional 5,000,000 tons of magnesite and 1,000,000 tons of brucite have been produced for use in making magnesia refractories and chemicals. Basic Inc., presently the only producer, mines 1.5 ± 0.25 million tons of ore and waste annually using high-selective open-pit rriethods; the ore is up-graded, calcined, and processed into a variety of products. Known reserves of highgrade (less than 5 per cent CaO) magnesite ore total more than 25,000,000 tons, and there are larger tonnages of lower-grade material; brucite reserves are small. The magnesite and brucite are in generally west-dipping dolomite of the upper member of the late Triassic Luning Formation, in the over-riding plate of the Paradise thrust fault. A great variety of dikes and a stock of Cretaceous granodiorite intrude the Luning Formation in the vicinity of the magnesite-brucite deposit. The magnesite bodies are scattered over an area of about a square mile around a prong of granodiorite which extends north from the stock. The brucite is mainly in two bodies in contact with the prong of granodiorite; at the surface and along deeper cracks the brucite has weathered to hydromagnesite and artinite. In the area of magnesite-brucite mineralization, much of the dark, fine-grained, schistose, regionally-metamorphosed dolomite of the Luning Formation has been marmorized to a lighter-colored, coarser-grained, massive dolomite that is intergrown in varying proportions with the magnesite. The magnesite and marmorized dolomite can not be distinguished visually. In addition to the two varieties of dolomite, the gangue in the magnesite and brucite bodies mainly is the various varieties of dike rock, serpentine and a variety of other "contact" minerals, and "post-ore" dolomite and calcite. The magnesite ( and recrystallized dolomite) is believed to have formed by the hydrothermal replacement of the regionally metamorphosed sedimentary dolomite; alternatively it has been suggested that the magnesite is sedimentarv and formed contemporaneously with the dolomite in an embayment of the Triassic sea. Because all the igneous rocks exposed in the immediate vicinity of the magnesite deposits appear to be younger than the magnesite, the ore-forming solutions are thought to be related to a somewhat older granite which crops out elsewhere in the area. The brucite is the result of contact-metasomatic replacement of magnesite during the emplacement of the granodiorite stock.

Jan 1, 1968

By Robert K. Linn

The New ldria Mining District is in the southern part of the Diablo mountains of the California Coast Range, 140 miles southeast of San Francisco. The district, noted primarily for quicksilver, also has become important recently as a producer of short-fiber chrysotile asbestos. Between 1853 and 1966, the New Idria district produced 568,092 flasks of quicksilver valued at about $55,600,000, 99 per cent of which was recovered from one deposit, the New Idria mine. In 1944, the district was ranked third in all-time production of North American quicksilver districts, and, since that time, the New Idria mine produced an additional 129,045 flasks, placing the district and the New Idria mine second in all-time production. The major structure of the region is the northwest-trending Coalinga anticline consisting of an asymmetric dome of sedimentary beds ranging in age from Jurassic to Quaternary and marked at its northwest end by an oval body of sheared serpentine 14 miles long by 4 miles wide. The serpentine core, rimmed by Franciscan sandstone of probable Jurassic age, was uplifted in stages between Jurassic and Quaternary time and was intruded along a ring of faults into beds of the Panoche Formation of upper Cretaceous age. The core of serpentine and Franciscan rocks is the locus of about 20 quicksilver mines that rim the faultbounded core and lie within the serpentine mass. The host rock of the most productive deposits is altered Panoche shale and sandstone that lies intermittently along the perimeter of the core. Deposits of the New Idria group of mines and those of a few other small mines lie along the northeast contact in the footwall of the New ldria thrust fault, and a few others occur on steep normal faults around the south and southwest. The chief ore mineral in all quicksilver mines is cinnabar, but minor amounts of metacinnabar and native mercury are found in some of the mines. Ore shoots were deposited in fracture zones and stockworks in altered Panoche shale and sandstone and in definite fissure veins in Franciscan sandstone. Rocks made highly amenable to fracturing by hydrothermal alteration were fractured extensively by late faults. The resulting fracture zones, located along the late faults and at changes in strike or dip of the hanging wall or footwall, are the principal controls of most ore shoots. The largest and richest ore shoots are those of the New Idria mine. The major ore bodies occur in fractured shale and sandstone beneath the New ldria thrust fault at its junction with major tear faults.

Jan 1, 1968

By John T. Cumberlidge, Frederic M. Chace

Nickel-bearing saprolite developed during the early Tertiary over a northeast trending ultramafic body of Jurassic age near Riddle in southwestern Oregon. The principal nickel mineral is garnierite, but other complex nickel minerals may be present. There are two main ore bodies, an upper (older) one associated with the Klamath peneplain, and a lower (younger) one on the Sherwood peneplain. Saprolite constitutes the bulk of the ore and was probably derived from peridotite and dunite through chemical decomposition by downward percolating meteoric groundwater. Decomposition took place by net loss of MgO, SiO2, and Fe without a change in volume. Faults and joints provided permeable zones which localized saprolite development, and faulting may have helped preserve some ore from loss by erosion. Garnierite-chalcedony boxwork ore was deposited by meteoric groundwater along faults, joints, and at the level of former water tables. Boxwork ore is entirely supergene, the chemical constituents having been derived from higher in the soil profile. The saprolites show evidence of both supergene and residual enrichment in nickel. Red and yellow soil occurs as a capping over saprolite and boxwork, and was derived from them by chemical and mechanical decomposition. The present deposits are probably truncated remnants of a formerly thicker and much more extensive deposit which probably included laterite at the surface. The deposits started to form in the early Tertiary due to deep chemical weathering under sub-tropical to warmtemperature conditions. Early Tertiary ero~ion surfaces of low relief probably contributed to the predominance of chemical weathering over mechanical erosion. Alteration under present climatic conditions favors the formation of soil from saprolite rather than the formation of new saprolite from peridotite.

Jan 1, 1968

By Sara J. Heinlein, George Malkos, James E. Lindell, Tony Pestonatto

The 79th Street Water Tunnel Extension Project was initially designed by the City of Chicago, Department of Public Works, to increase the capacity of the City’s south side water distribution system. MWH preformed a design review, prepared the final design and provided construction management for the City of Chicago Department of Water. Construction commenced in September 1995 and was completed in October 1999. The Project connected two existing water tunnels with a new 5.8 km (19,044 ft.) long, 4.9 m (16.08 ft.) finished diameter concrete lined rock tunnel utilizing TBM, drill-blast and mechanical hoe-ramming methods. In addition, approximately 61 meters(200 feet) of concrete lined variable cross section tunnel, a new gate shaft and a temporary construction shaft were constructed. This paper describes the construction of these features and the geological conditions encountered.

Jan 1, 2003

By J. A. Hudson

"The paper begins with a brief summary of Professor Müller’s formation of the ISRM and the contents of the previous six Müller lectures with their emphases on rock fractures. The geological origin of fractures is described via a deformational spectrum diagram and a matrix characterising the consequences of a sequence of superimposed deformational events. The different fracture frequencies encountered along lines in all directions through a fractured rock mass are explained. The value of computer modelling and simulation is demonstrated through an example of the effects of fracture zones on the distribution of the in situ stress field. The need to establish the validity of computer programs, i.e., that the modelling/simulation, does actually represent the rock reality, is discussed with reference to the work of the DECOVALEX project. Finally, examples are given of the effects of rock fractures on engineering design and construction, from pre-split blasting to caverns.INTRODUCTIONIt is a great honour to have been chosen as the recipient of the ISRM 7th Müller Award and I am grateful to the representatives of the International Society for Rock Mechanics (ISRM) National Groups who voted for me. In addition, I am especially pleased because my working life in rock mechanics and rock engineering has been devoted to understanding the geometry and mechanical properties of rock fractures and rock masses—which were the key subjects that Professor Müller promoted. In the ISRM 50th Anniversary Commemorative Book, Hudson and Lamas (2012), Professor Charles Fairhurst notes that on 24 May 1962, i.e., the day before the constitutional meeting of the ISRM took place in Salzburg, a reporter asked Professor Müller, “Do we know the strength of rock?”, to which Professor Müller replied, “For rock tested in the laboratory, yes. For a rock mass, no. This is what we need to determine. This is why we need an International Society for Rock Mechanics”. Also, in his Opening Address at the 1st ISRM Congress in Lisbon, Professor Müller, as the then ISRM President stated,“Many experts agree with me that discontinuity and anisotropy are the most characteristic properties of the material rock and that the properties of jointed media depend much more upon the fabrics bond of the unit rock block system than upon the rock material. Therefore any theoretical investigation of that material has to go its own ways, in the same way as the construction material of soils years ago suggested to soil mechanics its own methods, which differ greatly from the way of thinking of technical mechanics”."

Jan 1, 2015

By Antonio Raschillà

On the 2nd of June 2007 SELI S.p.A. started the excavation of Beles Tailrace Tunnel (Ethiopia). The new 8,07 m diameter DS Universal TBM utilized for the tunnel excavation was manufactured by SELI S.p.A. and allowed the installation of 30 cm thick concrete lining, contemporaneously with the excavation of 7,200 m of tunnel. The greatest part of the tunnel alignment was excavated in hard and sound basal-tic rocks. The paper describes the main steps of the tunnelling operations which led to a remarkably rapid excavation, with a peak production of 36 m / day and a final break-through achieved 46 days ahead of the contractual deadline. Furthermore the paper describes the work and logistic organization that was set up to efficiently perform the mechanized excavation in the very remote area of the project.

The following methods should be used to protect miners from the adverse health effects of exposure to respirable coal mine dust and respirable crystalline silica: ? Informing workers about hazards ? Establishing written emergency procedures ? Using engineering controls, work practices, and personal protective equipment (including respiratory protection when dust control equipment is being installed, maintained, or repaired) ? Monitoring exposures ? Conducting medical screening and surveillance ? Encouraging smoking cessation ? Maintaining medical records

Jan 1, 1997

By J. David Lowell

The discovery of the Kalamazoo (Arizona) ore body was a comedy of errors and coincidences and luck -as most discoveries probably are. The story began in early 1965 when Quintana Petroleum decided to diversify from petroleum into minerals and decided to do this by the route of minerals exploration. Quintana Petroleum is owned by the Cullen family of Houston and has Geen successful over the years in discovering oilfields. In 1965, the president and general manager was Corbin J. Robertson, son-in-law of Harry Cullen, founder of the company and a famous Texas wildcatter. But, in 1965, Quintana's financial advisors suggested that the company go into several mineral commodities, including copper, with Tucson, AZ, as the jumping-off point for copper exploration, and with a geological consultant (me) as the point man. The stage was now set! (See Fig. 1, location map of the San Manuel District, Arizona.)

Jan 1, 1991

By Robert Glass Cleland

[PHELPS DODGE COPPER PRODUCTS CORPORATION OFFICE, 40 WALL STREET, NEW YORK 5, N. Y. OFFICERS Whipple Jacobs President Howard T. Brinton Vice-President Edgar P. Dunlaevy Vice-President Weightman Edwards Vice-President S. Allan Jacobs Vice-President]

Jan 1, 1952

By Stanford O. Grodd

The Sanford Lake district encompasses an area covering 24 square miles in the central Adirondack Mountains of northern New York State. Discovery of the titaniferous magnetite deposits dates back to 1826. Several attempts to exploit the ores for iron prior to 1942 proved uneconomical because of difficulties with the associated titanium, lack of transportation facilities, and the isolated location. Since 1942, the National Lead Company has produced ilmenite concentrates for the titanium pigment industry, and a magnetite by-product used in the steel and refractory industries. Rocks of the area are Precambrian in age and of igneous origin. The area has a history of erosion, deformation, and metamorphism, subsidence, and finally uplift and glaciation. The resulting topography is extremely rough with drainage patterns controlled by a combination of fault patterns and glacial modifications. The district is within the large anorthosite massif making up the central high peak area of the Adirondacks. All of the various lowsilica rock types associated with the massif are found within the boundaries of the district. These consist of both the Marcy and Whiteface types of anorthosite and of gabbroic anorthosite, gabbro, and different grades of titaniferous magnetite ores. All of the rocks contain the same minerals and differ only in their percentages of these consitituents. Gabbro, and ore associated with it, demonstrate flow structure as both have foliation and lineation. Anorthosite and its associated ores are massive and show very little primary structure. Minor pegmatites and diabase dikes provide evidence of remobilization in selected areas and of late intrusion as well. Faulting is prevalent and follows a regional pattern of major faults trending northeastsouthwest and of minor faults at nearly right angles to them. There are four mineralized areas where an economic grade of ore has been found. Three of these have both gabbroic-type ore and anorthositic-type ore. The fourth has only gabbroic ore. Ores are graded according to their TiO, content, and these range from 9.5 per cent to over 30.0 per cent TiO,. Ore bodies of both types are related to gabbro and conform to the configuration of the gabbro bodies within the anorthosite. At least three distinct theories of ore genesis have been expounded by different investigators. Others propose some variations of one or more of these. Although complete agreement probably never will be reached, it is certain that no one process of ore emplacement can explain the complicated picture as seen today. Further understanding of the ores and their origin will require detailed mapping, sampling, and mineralogical studies of the entire district, and then it may never be understood without qualification.

Jan 1, 1968

By John Taylor

?Introduction to Black Mountain ?Historical metal accounting practice ?Metal accounting audit ?Feed measurement ?Sample precision ?Concentrate measurment ?Current metal accounting practice ?Further refinements to the metal accounting practice

Jan 1, 2005

By Willie Hefer

Contents ?Purpose ?Introduction ?Deviation of bias results ?Operational correctness ?Maintenance and Costs ?Conclusion ?Acknowledgements

Jan 1, 2005

By Paul Fouchè

Contents ?Purpose ?Introduction ?Why manage a mineral resource ?Sampling or tracking from source ?How can RF tracking help ?Project Goals ?RF System ?Tracer Layout ?Antenna

Jan 1, 2005

By André Fouché

GFWW Bulk Sample Prep Plant INDEX ?Features ?Flow Diagram ?Pictures of Plant

Jan 1, 2005

By Frank W. Dickson, George Tunell

Five hot spring areas of the western United States show evidences of present day deposition of HgS; two also show evidences of accompanying Sb2S3 deposition. Sulfide minerals are depositing at or near the surface from hot waters that differ for each spring ai:ea in amount and kinds of dissolved matter. All the springs contain dissolved substances that act as buffering agents and that cause increased alkalinity with increasing temperature. Transport of Sb2S3 is possible in H2O and in boron and sulfide solutions. Increasing alkalinity and temperature enhance stibnite solubility. Quantitatively important transport of HgS appears restricted to alkaline sulfide solutions that contain HgS2=. Elemental mercury probably forms in deep hot waters because HgS breaks down into mercury and sulfur above 200°C, and free S is removed by reaction with water. Elemental mercury should accompany HgS2= in solutions that were at 200°C or higher. Cinnabar deposits from saturated alkaline sulfide solutions because of combinations of temperature decrease, dilution, oxidation, and reactions with wall rock: Amedee Hot Springs, Boiling Springs, and Coso Hot Springs are areas in which HgS is the only sulfide deposited. Hot waters at Amedee and Boiling Springs are supersaturated with HgS or transport colloidal HgS. Steamboat Springs waters deposit mainly silica and stibnite, but they have deposited HgS recently. Sulphur Bank waters deposit mostly stibnite and some HgS. The hot-spring waters of all springs represent highly modified deep water. Field and laboratory studies support the concept of transport of HgS in moderately alkaline sulfide solutions as HgS2=. Fluctuating deposition of stibnite and cinnabar reflects availability of sulfide or variations in deep-source HgS and Sb,S,. Silica and HgS dissolve mutually in alkaline sulfide solutions, and cinnabar and quartz would be expected to deposit simultaneously. Free mercury given off by hot-spring waters would impregnate country rocks.

Jan 1, 1968

By Roger A. Bullivant

The introduction of this size and type of piling rig is intended to address a multipurpose foundation activity. The 8000 denotes the size of equipment that is attached to the mast, namely 8000 Kg. Larger equipment can be carried subject to adjustment of rig geometry. The 8000 series rig will easily accept hydraulic piling hammers and CFA equipment, but for the purpose of this discussion it will be equipped with an auxiliary power pack that is matched to twin vibrators. The design of the siamesed vibrators allows long tube equipment or piles to be driven with a short mast configuration that provides a lower overturning risk. It is easily adapted within minutes to carry out other foundation requirements that are required on the same contract. The piling and ground consolidation activities that can be undertaken by the 800 series machine are:-

Jan 1, 1995

By Mark G. Lafontaine

Underground 802.11 wireless communications has become widely adopted for automation and communication purposes but maximizing the wireless signal presents many obstacles given the harsh environment as well as the presence of materials and conditions that can reduce signal propagation. Changes in elevations and curvatures in ramp to drift transitions also affect the wireless signal. Based on the requirements of wireless applications such as voice, data, or location tracking, the wireless site survey is the key tool for measuring and predicting signal strength and signal-to-noise ratio. These readings help determine the maximum distance between access points in order to sustain an overlapping wireless signal where required. This paper describes the methodology and tools used for measuring 802.11 wireless signal strength in an underground mine environment in Northern Ontario. The physical characteristics of the mine and the actual recorded wireless signal data will be presented in order for the audience to gain an understanding of the factors that affect signal throughput. Antenna selection used for the site survey will also be discussed as it played a key role in propagating the wireless signal.

May 1, 2013

By L. C. Graton

At the Tenth International Geological Congress, Mexico, 1906, Waldemar Lindgren presented "The Relation of Ore Deposition to Physical Conditions." Retrospect ranks it as the outstanding offering at that Session and as the most fundamental contribution up to that date on the philosophy of ore deposition. Elaborating thereon in his text-book "Mineral Deposits," Lindgren analyzed ore-forming processes under conditions prevailing from great depth up to surface; explained the nature of deposition in each environment; and developed a comprehensive genetic ore classification, which brought wide acceptance and enriching contributions by many. Since Lindgren's latest edition (1933), have come wealths of material relevant to ore genesis, particularly through amazing renaissance and proliferation throughout science. Current publication regarding ores now emanates largely from a generation caught in pressures of the breathless modern tempo, which tempts scant reflection upon earlier truths. Consequently, today's thrilling output contains not a few offerings that need challenge because supplanting interrelationship and system by what seems, collectively, an assemblage of strange, ad hoc and often self-contradictory concepts. From these latter some merit may eventuate but at the probable cost of present confusion and delayed progress. The following pages, naming numerous post-Lindgren advances, record the conviction, held by many, that Lindgren's philosophy, progressively improved, remains the soundest approach to understanding ore genesis.

Jan 1, 1968

By John D. Ridge

Here are summarized 162 papers, published between 1933 and 1967, that deal with various aspects of ore genesis. Emphasis is placed on additions to, or modifications of, ore-formation theory, no matter what type of deposit is discussed. More space is given to papers on the formation of base-metal sulfides solely because more papers are written on this subject. The final conclusion is reached that a chemically and geologically sound theory for the genesis of ore deposits can be built around the concept of concentration of ore e’ements in a magmatically produced ore fluid and around such surface processes as may act to concentrate economically valuable materials from rocks of any origin exposed at the surface.

Jan 1, 1968