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By J. A. Morgan, W. A. Barclay, J. C. Pedersen, I. C. Campbell, D. S. Bubar, R. P. Taylor

"Abstract - The Lilypad Lakes property is host to a group of Ta-mineralized dikes that occur over an area of at least 10 km2. Field relationships are consistent with a syn- to late syn-tectonic timing for their emplacement (with respect to the major regional D1 episode of deformation), with several of the dikes exhibiting a steeply dipping, open, S- to M- to Z-shaped fold geometry. Individual dikes range up to 30 m wide (Rubellite Dyke, Pollucite Dyke), have strike lengths of up to 750 m (e.g., JJ Dyke), and are continuous to depths of greater than 250 m (e.g., Rubellite Dyke, Pollucite Dyke). Typically, they display sharp intrusive contacts characterized by the development of thin, holmquistite-rich haloes. The Tamineralized dikes are comprised of silica- and alumina-rich, sodic, granitic pegmatites that display extreme levels of geochemical fractionation (K/Rb typically < 10.0, as low as 2.2; Nb/Ta typically < 0.20, as low as 0.03), and enrichments in an economically important group of lithophile elements, most notably Li, Rb, Cs, and Ta. Geochemical assays of individual surface grab and drill core samples have yielded values as high as 1.51 wt.% Li2O, 1.25 wt.% Rb2O, 6.21 wt.% Cs2O, and 0.108 wt.% Ta2O5. Diamond drilling has established the presence of wide (~20 m), potentially ore-grade intersections of Ta mineralization (>0.045 wt.% Ta2O5) in both the Rubellite and the Pollucite Dykes.Three Ta-oxide minerals (microlite, wodginite, manganotantalite) of primary origin predominate in the Ta-mineralized dikes, where they occur as fine, disseminated grains in the albite-rich pegmatite matrix. The sequence of crystallization is typically manganotantalite wodginite microlite, which conforms to a well-established paragenetic sequence for rare-element granitic pegmatites in general. All three of the primary Ta oxides are characterized by a high degree of chemical purity (e.g., average Ta concentrations in microlite from 77-79 wt.% Ta2O5), a compositional feature consistent with the extreme levels of geochemical fractionation characteristic of the host granitic pegmatites, and one that indicates that the Lilypad Lakes pegmatites are likely to produce Ta mineral concentrates of the very highest quality.Locally, a second generation of Ta minerals is present, restricted to small vugs in the pegmatite matrix that are surrounded by fine aggregates of K-rich mica or clay. The secondary Ta minerals are dominated by microlite, which is typically intergrown with fluorite and Fe-sulphides, and is distinguished from its primary counterpart by its lower Ta content (around 70 wt.% Ta2O5) and much higher concentration of uranium (up to 9 wt.% UO2). Also, secondary microlite consistently yields low analytical totals from electron microprobe analysis, suggesting that it is H2O-rich. The presence of this second, vug-related generation of microlite, together with the occurrence of localized networks of crosscutting fractures that host high concentrations of Cs and Rb (in the minerals pollucite and Rb-Kfeldspar), suggests that a late-stage, fluid-dominated metasomatic/hydrothermal event may have been important in certain sections of the dikes, and has effected a redistribution of the economically important elements Ta and Cs."

Jan 1, 2005

By D. Laguitton

The basic chemistry of a1•senic related to its dissolution and subsequent precipitation in gold-mine waste waters is discussed. The lime addition methods provides the most economic treatment of arsenical slurries, but requires a careful control of the oxidation of Asm into Asv, of the pH (>12) and the filtration of the precipitate. If arsenic levels below 0.5 mg/ l are required, a modification of the method by phosphate addition must be considered.

Jan 1, 1976

By Heinrich Möller

The electro-oxidation of 0.1 M ethylene glycol at gold, platinum and gold-platinum alloy electrodes in different heat treatment conditions has been studied in 0.5 M NaOH, at room temperature. Poisoning of all the electrodes occurs. However, the alloy electrodes poison at a faster rate than the pure gold and platinum electrodes. This indicates that the initially higher activity of these electrodes cannot be the result of decreased poisoning through a "third-body" effect.

Oct 1, 2003

By S. G. Shabestari

Thermal analysis is a tool that is generally employed to predict the structure of the alloy before the actual casting is carried out. By cooling a sample of the molten alloy and recording the temperature-time curve, important solidification events may be analyzed by using the first derivative-cooling curve. In this research, strontium is added to (AS5U3G) 319 aluminum alloy and its influence on the formation of intermetallic compounds e.g. Al15(Mn,Fe)3Si2, Al2Cu, Al5Mg8Cu2Si6 formed during pre- and post-eutectic reaction have been investigated. Also any changes in solidification parameters such as temperature of Al-Si eutectic under cooling and temperatures of nucleation and growth of each phases caused by strontium addition, have been determined via the first derivative cooling curves. The effect of strontium on the formation of various intermetallic compounds has been studied by using very accurate thermal analysis equipment and the microstructures were analyzed using an optical microscope. The various phases reported in this paper were identified using Scanning Electron Microscopy (SEM) and linked to Energy Dispersive Spectroscopy (EDS). Formation of all pre- and post-eutectic phases was interpreted by comparing the phases formed in the microstructure and the reactions detected by using cooling curves. The results of this research indicate that thermal analysis technique can be used as an on-line process control in the production lines in aluminum casting industries.

Jan 1, 2004

By A. Saigal

The effect of temperature on the cutting forces during machining of alumina reinforced aluminum composites was investigated, Aluminum 6061, 10% Al2O3 reinforced composite and 20% Al2O3 reinforced composite were tested, A 5/8-inch diameter high-speed steel end mill, a Micro 100 TiN coated single edge endmill cutter and a two-fluted solid carbide insert cutter were used for tooling, The results, in general, showed an increase in the cutting forces as the temperature of the material increased, From the raw data, there are temperatures ranges in which the force data did decrease but they were insignificant with regards to predicting a downward trend. A regression analysis was used to understand which variables had the greatest affect on the forces being generated, The correlation and regression analysis showed that at 600 rpm (velocity: HSS- 98,2 sfpm, Micro 100 cutter - 78,5 sfpm, solid carbide cutter - 192,4 sfpm) the tooling, the workpiece material, built up edge, and temperature were statistically significant factors in the test, Tooling was a significant variable in all testing, The smallest forces recorded during machining were generated with the solid carbide two-fluted endmill cutter, Visually, the solid carbide tooling produced a better surface finish during the testing which made it the tool of choice, In addition, the force data proved that as the cutting speeds were increased, the cutting forces decreased.

Jan 1, 2005

By Laura Prati

Gold-on-carbon catalysts resulted very active and selective in liquid phase oxidation [1, 2, 3] and during past studies we established that activity is ruled by two factors: particle dimension and gold exposure on the carbon surface [4]. These two parameters are also connected to the nature of activated carbon where the chemical nature of the surface oxygenated groups probably plays an important role [5]. Our studies, focused on the design of an active gold-on-carbon catalyst for liquid phase application, were aimed, operating a fine tuning of all the parameters involved in determining activity, to optimize gold-on-carbon preparation, keeping in mind that gold particle activity increases with decreasing particle size and increasing gold exposure. Gold sol immobilisation represents a versatile methodology in preparing gold catalysts [6]: throughout this work we used as sol stabilizing agent, the N-dodecil-N,N-dimethyl-3-amino-1-propan sulphonate (SB), that provides both sterical and electrostatic stabilisation, a condition we already demonstrated necessary to preserve particle dimension when carbon is used as the support [6]. We generated different gold sols by varying the relative amount of reagents (HAuCl4, SB, NaBH4), the type of alkali and the temperature of the gold precursor reduction. Moreover, as we had recently evidenced that there is also a carbon effect [5], we employed only one active carbon to immobilize the sols.

Oct 1, 2003

By A. Ojaghi, A. R. Mohammadi

"The Marvast monazite deposit is located 35 kilometres south - southwest of Marvast in Yazd province of Iran. A representative sample weighing approximately 10 tons was prepared to study the amenability of the ore to physical beneficiation. The size fraction of +1000 µm was removed due to low monazite content and the –1000 µm size fraction was concentrated by the gravity-classification-magnetic methods. According to the results of sample characterization, the representative sample contains 220 ppm REO that is contained in monazite. It was concentrated to 41.5% REO by the above mentioned methods. The recovery of REO in the monazite concentrate was 41.5%.INTRODUCTIONRare earth elements are critical metals in many countries (Gupta, 2005; UK Geological Survey, 2011). Increasing application of these metals in hi-tech industries and price fluctuation caused by Chinese production policy has led other countries to focus on their local resources (UK Geological Survey, 2011). In this case, Iran is not an exception.REE mineralization in Iran is mainly located in the central zone. Regarding the exploration data, these deposits are divided into two categories. The first group is iron ore deposits in which the REE are carried by phosphate minerals. The other group is placer deposits where monazite is the major mineral of the deposit. The Marvast placer deposit is one of these types of deposit (Daliran, 1990; Mokhtari, 2008; Torab, &Lehmann, 2007; Alipour, 2014)."

Jan 1, 2016

By Louis R. Bernier

Since 1978, most systematic studies of AMD passive treatment with limestone drains (LD) have dealt with coal mines in the United States. The authors present in this paper the first results of a triennial study initiated in 1999 on the performance of LD installed at the Ni-Cu Lorraine old mine site in Temiscamingue during a remediation plan that involved the installation of a cover with capillary barrier effects (CCBE) over the reactive pyrrhotite-rich tailings. Typically, a LD is a trench enclosed by impervious materials filled with crushed limestone and may be oxic or anoxic. Four LD (one filled with marble and 3 with dolomite) were installed at the Lorraine site. The LD have been in operation since May 1999 and are performing differently. The most contaminated mine effluent flows south and is directed towards 3 LD filled with crushed dolomite, while a 4th LD was filled with crushed marble and installed west. The LD filled with marble has been generating maximum alkalinity since the beginning of the passive treatment. Two of the dolomite drains have been generating alkalinity since mid-summer 1999, but one is not, even if a substantial pH raise was observed. A pH above 5.5 is required usually for the dolomite drains to start generating alkalinity. The installation of LD at the Lorraine site contributes significantly to the reduction of metals and sulphates loading.

May 1, 2001

By G. Riveros

A new, continuous fire refining process for copper has been developed and tested at the 5 tph pilot scale. During oxidation, the blister copper flows through a packed bed of crushed refractory bricks counter-current to a hot oxygen containing gas. The resulting desulphurized copper flows then directly into a packed bed of charcoal for deoxidation. By controlling the air to natural gas ratio, both temperature and reducing conditions can be controlled. Based on extensive laboratory scale measurements of the rate of copper oxidation and reduction, the process concept was developed aided by process modeling and simulation. The industrial-pilot scale installation built at the ENAMI Paipote smelter in Chile, consists of two cylindrical, compact reactors, operating in line, with a designed capacity of 5 t/h of blister copper. The results of the industrial-pilot tests confirmed the feasibility of the new process. The blister copper processing capacity was increased to 10 t/h with satisfactory sulphur removal. The degree of oxidation as well the copper temperature was controlled with relative ease. The specially designed siphon block allowed for smooth tapping of the oxidized copper and separation of refining slag. The reduction of oxidized copper in the packed bed of charcoal appeared to be very effective while control of the degree of reduction according to the height of the bed ensured control of the oxygen content in the refined copper at the required level.

Jan 1, 2007

By Ibrahim Ocak

The prediction of machine utilization time and determining machine performance plays an important role in scheduling and planning tunnel excavation and data base created serve a major role in further applications. In this study, the construction methods of two twin tunnels situated between Basak Konutlari station and Istoc station are summarized. Geology in the study area is composed of fill and weak rock, respectively starting from the surface. The tunnels of 5.6 km in length were excavated with two different earth pressure balance machines (EPBM). Excavation diameters of the EPBMs were 6.564 m. The performance of the machines are analyzed and compared in order to accumulate data for further applications in similar ground conditions in Istanbul. The distance between two twin tunnels is 14 m from center to center and the EPBM in the one tube was almost about 100 m behind the other tube. Segmental lining with 1.4 m of length and 30 centimeters of thickness were used as final support. The overall performances of the two Lovat TBMs are found to be respectively as; the best daily advance rates 30.8 m/day and 30.8 m/day, the best weakly advance rates 115.0 m/day and 153.9 m/day, the best monthly advance rates 388.7 m/day and 400.5 m/day. Total waiting and maintenance times were 25.2 and 16.7 %, respectively.

Aug 1, 2013

By C. O. Aksoy, H. Kose, K. Ozfirat, T. Malli, A. Gonen, S. Gurgen

In selecting mobile mining equipment, factors including availability, useful economic life, maintenance and operating costs, and spare parts availability are considered. Given these factors, trucks and shovels with different capacities are selected. Optimizing equipment for pit and hillside quarry cases, where 8% and 10% ramps are commonly in use, were examined; the effect of other mining activities such as drilling and blasting on unit cost were considered. In principle, 20 m to 25 m high benches should be economical for downhill haulage, and 7 m to 10 m low benches economical for uphill haulage. However, practice of both mining styles favours 10 m to 15 m bench heights. Hence, the analysis here was carried out with the field experience bench height range. In the study, a truck-shovel optimization was based on the movement of 5 to 20 million cubic metres (in 2.5 million cubic metre increments) of overburden stripping at the Eynez open pit mine in the Soma region of Turkey. The outcome showed that low-capacity shovels were unfavourable due to high production expectations. High-capacity shovels were also unfavourable due to health and safety issues causing high instances of impact vibration on trucks during the loading cycle and a decrease in foreseeable unit lifetimes. The number of shovel passes required to load a truck ranged from three to six. Trucks with high-capacity bodies were deemed uneconomical due to high investment and operating costs.

Jan 1, 2005

By Jie Li, Xinyu Liu, Yan Chen, Linjian Ma, Yasong Wang

Nonlinear time-dependent response analysis of salt cavern under extreme loads in disaster mode is of great importance to the safety and disaster prevention of gas storage group. Uncontrolled blowout is one of the extreme conditions for compressed-air cavern operation. Based on the geological structure of Jintan salt deposit, China, the numerical model of the complete process of water solution, cyclic operation, and internal pressure runaway was developed. The effects of rapid unloading on the stress filed, the progressive failure of surrounding rock, the volume convergence of storage cavern, and the ground subsidence were simulated employing an elasto-viscoplastic damage constitutive equation for rock salt. The results indicate that the damage and failure zones propagate much larger in the mudstone interlayer than in the host salt. The volume of damage and failure zones surrounding salt cavern induced by unloading process is 5~6 times that of cyclic injection and withdrawal process. The average volume convergence rate of salt cavern reaches 0.012%/d~0.013%/d, which is 6~6.5 times that induced by cyclic operation. The ground subsidence exhibits a typical funnel curve. The affected region of ground subsidence due to rapid unloading in the blowout period is about two times the maximum cavern diameters. Furthermore, double cavern analysis reveals that the interaction between adjacent caverns may be ignored so long as the pillar width is larger than two times the maximum cavern diameters.

Jan 1, 2015

By A. Rodriguez-Prado

"Magnetic fields affect the growth of cultured cells and plants; however, limited information exists about their effects on vegetation performing environmental remediation. Constructed wetland mesocosms treating hexavalent chromium (Cr(VI)) wastewater exposed to low-intensity magnetic fields (60 Hz, 56.5 × 10-6 Tesla) produced 100% more biomass than the unexposed control. Nonetheless, they removed only 43 ± 27% of Cr(VI), compared to 60 ± 21% for the control. A Cr(VI) reduction expression was developed as a function of the magnetic field. The design and operation of constructed wetlands to treat mining wastewater can be corrected for magnetic field effects.RÉSUMÉ Les champs magnétiques affectent la croissance des cellules et des plantes cultivées; toutefois, il existe peu d’information quant à leurs effets sur la végétation utilisée à des fins d’assainissement environnementale. Les mésocosmes des marais artificiels traitant des eaux usées, contenant du chrome hexavalent (Cr(VI)), exposés à des champs magnétiques de faible intensité (60 Hz, 56,5 × 10-6 Tesla) ont produit 100 % plus de biomasse que le contrôle non exposé. Néanmoins, ils n’ont enlevé que 43 ± 27 % du Cr(VI), comparativement à 60 ± 21 % pour le contrôle. Une expression de réduction du Cr(VI) a été développée en tant que fonction du champ magnétique. La conception et l’exploitation de marais artificiels pour traiter les eaux usées des mines peuvent être adaptées pour tenir compte des effets des champs magnétiques."

Jan 1, 2015

By B. G. Cousins, B. O’Rourke, C. Spence

"Some non-flotation chemicals are added to flotation circuits directly and indirectly to control issues such as scaling and dust in other areas of the operations. Since dosage levels are generally not high, a standard laboratory float test may not be able to determine the effect of a specific chemical on the productivity of the flotation circuit. This paper presents a laboratory testing protocol that uses kinetic float studies to test the effect of normal to extreme doses of antiscalant and dust chemistries (5–100 g/t). Results indicate that this protocol helps to predict potential interference by a particular chemistry on the flotation circuit.RÉSUMÉ Certains produits chimiques ne servant pas à la flottation sont ajoutés directement et indirectement aux circuits de flottation afin de contrôler des problèmes tels que l’entartage et la poussière dans d’autres secteurs des opérations. Étant donné que les niveaux de dosage sont généralement faibles, un essai standard de flottation en laboratoire pourrait ne pas être en mesure de déterminer l’effet d’un produit chimique spécifique sur la productivité du circuit de flottation. Le présent article définit une procédure d’essai en laboratoire qui utilise des études cinétiques de flottation pour vérifier l’effet de doses normales à extrêmes de produits chimiques antitartre et anti-poussière (5 à 100 g/t). Les résultats indiquent que ce protocole aide à prédire l’interférence potentielle d’un produit chimique particulier sur le circuit de flottation."

Jan 1, 2016

By Raymond D. Potts

"Minntac is a taconite mining, concentrating and pelletizing operation located near the town of Mountain Iron, Minnesota, U.S.A. It is totally owned and operated by USX Corporation and represents its largest source of domestic iron units. Minntac began producing fluxed pellets in 1988 and has produced both acid and fluxed pellets since then. This paper compares the acid and fluxed pellets produced at Minntac. It reviews modifications that have been made to the plant flowsheet and discusses areas recognized for improvement since the beginning of fluxed pellet production. It also comments briefly on the performance of Minntac fluxed pellets in USX blast furnaces and the future of fluxed pellets at Minntac.IntroductionMinntac was built in three steps with each step designed to produce 6 million long tons of acid pellets per year. The actual production has varied though. Figure I shows the production by year at Mirmtac. Step I began production in 1967, Step 2 in 1972 and Step 3 in 1978. Mirmtac produced 16.5 million tons in 1979 but only 3.5 million tons in 1982 when the facility was shut down for six months because of the lack of demand for pellets. Since the initial start up, Mirmtac has produced over 200 million long tons of pellets. Until 1987, all the pellets produced were ""acid"" pellets. In 1987, equipment to produce ""fluxed"" pellets was installed and tested. In 1988, full scale production of fluxed pellets began."

Jan 1, 1991

By C. R. Kerr

"This paper describes the revisions to the heating and ventilating system at the Frood-Stobie mill, which resulted in substantial savings in energy costs.IntroductionInco Metals Company, a unit of Inco Limited, is involved in the mining and processing of nickel-copper ores. The Ontario Division of Inco Metals consists of 10 operating mines, with 5 mines and open pits on a standby basis, and 10 pro- cessing facilities, located in Sudbury, Port Colborne and Shebandowan. In 1980, the Ontario Division&apos;s energy expenditures amounted to $87,000,000.Due to the accelerating cost of energy, the Division established an Energy Management Program in 1975 to define, evaluate and implement measures to reduce energy cost and consumption per unit of output by 10% by 1980. This falls in line with the goals set by the mining and metallurgical task force on voluntary energy conservation.To effectively implement the program, Plant Committees were established at each plant and mine area, with an energy management coordinator appointed to coordinate the activities. The Plant Committee&apos;s responsibilities include identifying the major areas of energy consumption, isolating areas with large potential losses and determining what action should be taken to improve energy efficiency.Within a five-year period from 1975 to 1980, the Ontario Division has been able to cut its energy consumption by 8.9 trillion BTUs, the equivalent of 1.5 million barrels of oil."

Jan 1, 1981

By P. R. A. Andrews, R. K. Collings

"SUMMARYIn cooperation with the Ontario Ministry of Natural Resources, selected deposits of Potsdam sandstone in the Ottawa-Kingston area were core-drilled and evaluated by CANMET as potential glass and foundry sand. Analyses of cores ranged from 84.6 to 98.5% Si02, 0.09 to 0.65% Fe203&apos; and 0.07 to 2.10% A12°3&apos; The cores were largely composed of white to grey, relatively tough sandstone. Impurities included iron as pyrite, iron oxides and staining on the quartz grains; carbonates as calcite; and aluminum oxide as feldspar. Beneficiation included size reduction to grain size, about 600 um, by jaw, roll and cone crushers, and grinding in a muller-mixer. Removal of fines was achieved by attrition scrubbing and washing. Further removal of impurities was achieved by reverse flotation of pyrite, iron oxide, feldspar, and carbonate minerals employing both anionic and cationic collectors. Flotation resulted in a substantial improvement in the quality of most samples; analyses of quartz concentrates showed 98.5 to 99.7% Sial> 0.022 to 0.156% Fe203&apos; and 0.07 to 0.62% A1203. Further reduction of the iron content by wet magnetic separation and acid leaching also was investigated. On the basis of the samples submitted, sands/ones from six of the seven deposits studied have potential as sources of glass sand. Foundry sand tests were inconclusive because of the small quantities available for study."

Jan 1, 1986

By R. D. Westervelt

IN JULY 1954, the first iron ore from the deposits in the Knob Lake vicinity was mined and shipped to Seven Islands. The beginning of the production may well be the greatest advance in Canadian economy in the past fifty years. In 1955, the Canadian iron ore output was more than twice that of 1954, an in-crease due principally to the iron ore shipments from the Knob Lake area. Previous to this, Canada&apos;s iron production was 1.85 per cent of the world&apos;s output. Now, this percentage has risen to approximately 5.5 per cent and shows every indication of increasing further as the production rate from the area is increased. In 1955 the Iron Ore Company of Canada shipped over 7 million tons of iron ore and expects to ship over 10 million tons in 1956. Present facilities may be enlarged to handle up to 20 million tons per year. If the expected I 0 million tons per year are exported, Canada&apos;s iron exports will be second only to her wheat and newsprint exports. Before production began from the Knob Lake deposits, years of development were necessary in the area. Geologists spent several summers mapping the general area in order to unravel the complicated stratigraphy and petrology. Particular attention was paid to the mapping of the iron formation and all stages of alteration from fresh iron formation to ore were observed.

Jan 1, 1957

By X. W. Yi, Z. J. Li, G. W. Ma

In this paper, the compressive strength and failure patterns of reinforced cemented paste backfill (CPB) were studied aiming to promote the stability of backfilled stopes. The concept of ductile backfill was proposed and a series of unconfined compression tests were carried out on both non-reinforced and reinforced cemented paste specimens. Portland cement (3% to 5% by weight of tailings) and five different types of ductile materials (0 to 0.5% by weight of solids) were employed in this experiment for the specimen preparation. The test results showed that inclusion of ductile materials enhanced the unconfined compressive strength (UCS), reduced the post peak stress loss and transformed the failure behaviour of specimens from classical brittleness to ductility. The strength of CPB reinforced with different proportions of polypropylene fibres was compared. The stress-strain curves illustrated that both cement and fibres contributed to the increase of UCS, but higher strain values at the peak stress were achieved by fibre reinforcement. CT sliced images acquired from X-ray computed tomography (CT-scan) demonstrated that the reinforced specimen developed irregular crevices at the edge of cross sections and gained the capacity of bearing large displacements owing to the mobilised tensile strength of fibres. It leads to the potential of avoiding unexpected falling blocks of CPB when adjacent mining occurs. This finding highlights a strategy to improve the self-supporting capacity of the fill mass with less cement usage and reduce the ore dilution rates when excavating to adjacent stopes.

Jan 1, 2015

By R. H. Seraphim

"The Phoenix Camp, in the Boundary Creek district of southern British Columbia, produced before 1920 about 15 million tons of ore averaging more than l ·5 per cent copper, about 0.03 ounces per ton in gold, and 0·5 ounces per ton in silver. Attwood Copper Mines Ltd. conducted an exploration program in the Phoenix area from 1951to1953.Publications on the camp are listed in the bibliography. Brock's work was not sufficiently detailed to unravel the structural and stratigraphic pro bl.ems. The work of LeRoy and McNaughton is referred to later.The stratigraphic column is as follows:Tertiary.Midway Formation: Volcanics and hypabyssals; dacitic to basaltic flows, with associated dykes and sills of syenite (pulaskite in part) and augite porphyry.Jura-Cretaceous.Intrusives of quartz diorite and diorite (nearest outcrop two miles from Phoenix).Late Palaeozoic or Triassic (Attwood Series).Brooklyn Formation: Sharps tone conglomerate, limestone, grey-wacke and/ or andesitic tuff, with minor shale and basalt. Rawhide Formation: shale with minor conglomerate.Early Palaeozoic.Knob Hill Formation: Chert and andesite, with minor limestone, shale, and serpentine.This column differs from that of LeRoy in two important respects: (I) Attwood's work indicates that the Rawhide shale is basal to, rather than stratigraphically above, the Brooklyn formation. The shale contains conglomerate lenses, which become more abundant and thicker toward the top, and grades upward into Brooklyn conglomerate. Ripple marks indicate that the shale is right side up."

Jan 1, 1949