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INTRODUCTION Porphyry copper deposits have been reported from the Caribbean area by Pease (1966), Cox, et al. (1973), Guild (1974), Kesler, et al. (1975), and others. This chapter summarizes the most widely known characteristics of those deposits. Only one deposit that conceivably can be classed as a porphyry copper occurrence is in production (Pueblo Viejo, Dominican Republic), but others are known whose tonnage and grade are of economic interest. Deposits in this province may be classified as copper-gold or copper-molybdenum types (Kesler, 1972), but deposits associated with quartz-rich plutons that have high Na2O:K2O and high gold:copper but low molybdenum: copper ratios dominate. Porphyry copper occurrences are reported in the literature from Puerto Rico, Haiti, the Dominican Republic, Jamaica, and Cuba. Only the porphyry copper deposits from Puerto Rico are extensively described in the literature; consequently the Caribbean porphyry copper province in general is not as well documented as the southern Cordilleran orogen. Because past published technical descriptions are incomplete, some data presented here are new to the literature. The Caribbean includes the island arcs between North and South America. Porphyry copper occurrences are known from the Greater Antilles, the generally east-west trending group of islands that lies south of North America. Fig. 48, therefore, only covers the Greater Antilles portion of the Caribbean. Porphyry copper deposits in this area are not described by the Lowell and Guilbert (1970) model in details of metallization (general paucity of molybdenum), alteration (scarcity of orthoclase), or petrography (preponderance of quartz diorite). Therefore, this model should be modified to include deposits associated with quartz-bearing plutons such as those found in the Caribbean. In the Meme deposit on Haiti ore occurs in skarn adjacent to the quartz diorite phase of a composite quartz monzonite-granodio-rite-quartz diorite pluton (Kesler, 1968). This deposit, with a K-Ar 66 m.y. date, is not included in Fig. 48 as a porphyry copper deposit because metallization is restricted largely to the intruded rocks. Although the intrusive rocks at the Meme deposit may contain sulfide near skarn contacts they are otherwise essentially unaltered. Porphyry molybdenum deposits as defined by Clarke (1972) have not been reported in the Caribbean area.

Jan 1, 1978

By L. W. Saperstein, W. W. Kaufman

Stimulated by the hearing protection clauses in the 1969 Coal Mine Health and Safety Law, attempts were made to determine what safety hazards, in terms of warning signal discrimination, are attendant upon the wearing of hearing protectors. Warning signals of dangerous roof conditions were collected and analyzed from 11 different coal mines in four different coal seams. Primarily, signals of audible level emanating from roof, floor, or coal were recorded. The interpretations of these signals were seen to be very dependent upon coincident visual and tactile signals. Acoustic character of such signals is shown to be dependent upon the spectral energy distribution of the pulses. Roof talk signals generally have broad-band spectra concentrated below 5 kHz. Reverberation times of acoustic pulses are generally less than 0.5 sec in duration. Indications have developed which link the coal mine entry dimensions with the nature of noises recorded there. Related experiments suggest that roof talk can be discriminated from background noise equally well when wearing protection as when not. This conclusion is only appropriate when noise levels warrant the wearing of protection. When quiet, the wearing of protection somewhat reduces discriminatory ability.

Jan 1, 1976

By W. S. Burbank, B. S. Butler

STUDY of the ore deposits of Colorado has disclosed, in numerous places, sharp changes in both mineralogy and metal content of the primary or hypogene deposits with change in depth. A clear understanding of the meaning of these changes is requisite to form intelligent conclusions that can be applied in the exploration of such ore deposits. This paper is an attempt to set forth some of the geologic and chemical relations of minerals that bear on this problem. The effect of the differing electrode potentials of elements on the order of oxidation and on the order of displacement of one metal by another metal in supergene sulfide deposits has been studied for many years by several investigators. The results all agree rather closely with the original Shurmann series of replaceability of metal sulfides, as Wells has shown.1 So far as the writers are aware there has been little attempt from the geologist's viewpoint to correlate the electrode potentials of the elements, other than those of the common metals, with the positions and mode of combination of the elements as found in ore deposits, and in particular in hypogene deposits. Wells2 discusses electrochemical activity between solutions and certain ore minerals and mentions the possibility of its effect in precipitation reactions. The senior writer for a number of years has emphasized the importance of oxidation-reduction reactions as a factor in the formation of certain hypogene ore minerals, and as the electrode potentials are a measure of the relative Oxidizing and reducing power of the elements and their ions, it seems possible that a study of them may offer some suggestions on certain problems. The data at present available for such a line of

Jan 1, 1929

By H. G. Doll

A new electrical logging method is described which measures the resistivity of small volumes of material near and behind the wall of the bore holes. The very small electrode systems used are supported in the face of the flexible insulator pad of appropriate dimension maintained in contact with the wall. The measurements are recorded simultaneously with two different electrode spacings. This method provides a very detailed record of the formations and particularly of the permeable beds traversed by the bore holes. The application of MicroLog to the location of permeable zones within compact formaltions, such as limestone, and to the determination of the amount of sand existing in sequences of thin shale and sand streaks is discussed. The possibility of quantitative determination, providing a step toward the evaluation of formation porosity and mud cake thickness, is also examined. Field examples illustrate the essential features of the method. INTRODUCTION In conventional electrical logging, the spontaneous potential (SP) log is used to delineate the permeable beds, and the resistivity logs are used primarily to provide indications concerning the fluid content of the beds. When the formations are much more resistive than the mud, as happens, for example, in limestone fields, the SP currents are short-circuited by the more conductive mud column, with the result that the SP log is quite rounded. In that case, the SP log generally gives the approximate location of the permeable formations but it cannot be used for an accurate determination of the boundaries of each permeable bed.' Solutions for the problem of obtaining a better determination of the permeable beds in limestone fields were developed from two angles. One approach consisted in improvements to the logging of the SP, as given by Selective SP logging and Static SP logging. These new methods, which have been described in an earlier paper,' give good results when the mud is not too salty, but they are still in a somewhat experimental stage, mostly because the development efforts have lately been concentrated on another approach to the problem, i.e., the MicroLog.

Jan 1, 1950

By R. V. Higgins, A. J. Leighton

A fast method is needed for calculating thoroughly the performance of two-phase flobr~ in reservoir rock with complex geotrietry. The authors present such a method and .slzow its accuracy by romparison with laboratory performrrnce of a five-spot pattern. In making the performance c.alculations, the octant of the five-spot pattern was divided into four channels. The computer tinle required for the culculation was one rllinrcte. This is rorighly about minute per channel. INTRODUCTION By using an electronic computer it is now possible to make reservoir performance calculations in which fewer assumptions and more significant variables are included than was possible with a desk calculator. These performance calculations include such variables as the properties of the reservoir rock and its contained fluids, properties of the rock-fluid system and even different well-spacing patterns. Usually, the more variables that are included the higher the computer cost—and time on the computer is expensive. As a result, a short procedure is needed so the many variables will be included and accurate performance calculations will result. If a reservoir is composed of alternate layers of permeable and impervioi~s rock, and if each conducting layer has a different relative permeability, the combined computer cost for calculating each layer by the present long computer programs (which includes different well-spacing patterns and other variables) would be expensive. The performances of complex spacing patterns in a field often are studied by a potentiometric model, but in these model studies the analogy is to the flow of only a single phase. This paper presents a procedure to calculate the performance of a five-spot pattern with two phases flowing using a potentiometric model as a guide for the dimensions of channels and other related data. The time required to calculate the complete performance is about one minute on the IBM 7090 or four minutes on the IBM 704. The procedure can be extended to calculate the performance of more complex well spacings or an entire field with little modification. The procedure has been tested on the performance of the laboratory water floods of a five-spot pattern reported by Douglas, et alThe range of viscosity ratios in the laboratory experiments is from 0.083 to 754, which is extensive. The accuracy of the performance calculations is excellent as shown by the plotted points in Fig. I. The recovery as influenced by the geometry of the five-spot, taking into account the deviation from true radial character, has been predicted by Aronofsky and Ramey." The authors used a potentiometric model to determine the sweep efficiency to breakthrough of the flooding agent. Dyes, Caudle and Erickson,' by means of a laboratory model, show the influence of mobility ratio on recovery after breakthrough of the injected material. Dyes, et ai, used the X-ray shadowgraph technique and miscible phases in their studies. Craig, Geffen and Morse from the analysis of the performance of their laboratory model correlate many variables, including average saturation of a flooding agent determined by permeability relationship. Craig, et al, used X-ray shadowgraphs to determine the sweep efficiencies in sandstone models. In this report the sweep efficiency is not needed, and the important effect of continuously changing saturation gradients before and after breakthrough

By G. R. Rubly, H. J. Steele

The San Manuel property is in town&ips 8S and 9S, range 16E, Gila and salt River Base and Meridan, State of Arizona. This area is in the Old Hat mining district, southern pinal county, and is about 31/25 miles southwest of the town of Mammoth on the San Pedro River And one mile south of the Mammoth mine at Tiger, Arizona, The property consists of over 150 contiguous lode claims. The old Hat district was prospected prior to the civil war, but there was little or no production until 1881.1 The chief producers have been the Mammoth and Mohawk mines, now consolidated and operating as the st. Anthony Mining and Development Co., Ltd. Production to 1936 was $5,200,000, of which 83 pet was gold.2 Since 1940 the production has been chiefly lead and zinc, and some molybdenum and vanadium. There are a few small properties in the vicinity that have produced very minor tonnages of copper ore. In the San Manuel group there are claims which have been held continuously from 1906 to the present time, and at least two churn-drill holes were put down on or near the outcrop in 1917. No logs for these holes are available, but it is assumed that the grade of copper encountered was not sufficient to encourage further exploration. A small amount of ore has been shipped from open cuts on the San Manuel outcrop area, but there is no record of the tonnage Or grade. It is estimated that not more than 50 tons were mined. These cuts, plus a few shallow shafts and some short adits indicate limited and unenthusiastic prospecting at San Manuel. In 1942, through the efforts of James M. Douglas, R. B. Giffin, Victor Erickson, and Henry W. Nichols, owners of the Sari Manuel group, the Reconstruction Finance Corporation and War Production Board authorized the United States Geological Survey to investigate the property, and by their recommendation, the United States Bureau of Mines was authorized to put down a limited number of churn-drill holes. The Bureau of Mines carried On drilling from November 1943 to February 1945 Seventeen holes were drilled, varying from 305 to 1990 ft in depth. The property was brought to the attention of Magma Copper Co. in June 1944, and an option agreement was made with the Owners. Subsequently, a group of claims lying north of the original group and held by the Apex Lead Vanadium Mining Corp, and a group to the east held by the Quarelli family, were optioned. A drilling program was laid out to conform to the Bureau of Mines pattern, and drilling started in December 1944 Sari Manue1 Copper Corp. was incorporated September 1945, and has carried on the exploration program to the present time. Geology General The mineralized outcrop, chief copper mineral of which is chrysocolla, is a tri-

Jan 1, 1949

By G. R. Rubly, H. J. Steele

The San Manuel property is in town&ips 8S and 9S, range 16E, Gila and salt River Base and Meridan, State of Arizona. This area is in the Old Hat mining district, southern pinal county, and is about 31/25 miles southwest of the town of Mammoth on the San Pedro River And one mile south of the Mammoth mine at Tiger, Arizona, The property consists of over 150 contiguous lode claims. The old Hat district was prospected prior to the civil war, but there was little or no production until 1881.1 The chief producers have been the Mammoth and Mohawk mines, now consolidated and operating as the st. Anthony Mining and Development Co., Ltd. Production to 1936 was $5,200,000, of which 83 pet was gold.2 Since 1940 the production has been chiefly lead and zinc, and some molybdenum and vanadium. There are a few small properties in the vicinity that have produced very minor tonnages of copper ore. In the San Manuel group there are claims which have been held continuously from 1906 to the present time, and at least two churn-drill holes were put down on or near the outcrop in 1917. No logs for these holes are available, but it is assumed that the grade of copper encountered was not sufficient to encourage further exploration. A small amount of ore has been shipped from open cuts on the San Manuel outcrop area, but there is no record of the tonnage Or grade. It is estimated that not more than 50 tons were mined. These cuts, plus a few shallow shafts and some short adits indicate limited and unenthusiastic prospecting at San Manuel. In 1942, through the efforts of James M. Douglas, R. B. Giffin, Victor Erickson, and Henry W. Nichols, owners of the Sari Manuel group, the Reconstruction Finance Corporation and War Production Board authorized the United States Geological Survey to investigate the property, and by their recommendation, the United States Bureau of Mines was authorized to put down a limited number of churn-drill holes. The Bureau of Mines carried On drilling from November 1943 to February 1945 Seventeen holes were drilled, varying from 305 to 1990 ft in depth. The property was brought to the attention of Magma Copper Co. in June 1944, and an option agreement was made with the Owners. Subsequently, a group of claims lying north of the original group and held by the Apex Lead Vanadium Mining Corp, and a group to the east held by the Quarelli family, were optioned. A drilling program was laid out to conform to the Bureau of Mines pattern, and drilling started in December 1944 Sari Manue1 Copper Corp. was incorporated September 1945, and has carried on the exploration program to the present time. Geology General The mineralized outcrop, chief copper mineral of which is chrysocolla, is a tri-

Jan 1, 1949

By J. W. Rutter, K. T. Aust

Observations are presented of the formation of annealing twins during the growth of a recrystallized grain into a striated, melt-grown crystal of high-purity lead. The formation of an annealing twin resulted in replacement of the original migrating boundary by a large-angle grain boundary of the caincidence-site type or by a near-twin boundary. The results support the Fullman-Fisher theory of annealing twins and demonstrate the usefulness of the coincidence-site model. FULLMAN and Fisher1 have advanced the following theory to account for the formation of annealing twins during grain growth. Whenever a grain A grows into a matrix of grains S1 and S2, a twin A' of grain A may form, as shown in Fig. 1, if the following energetic condition is satisfied: where "E" and "a" refer to the specific interfacial free energy and the area, respectively, of the boundaries indicated by the subscripts. In effect, the twinned grain will persist when the energy of the boundary between the twin(A') and the matrix grain (S, or S,) is less than that of the boundary between the original growing grain (A) and the matrix grain by an amount which exceeds the energy of the coherent twin boundary between A and A'. Experimental observations on the changes in grain boundary free energy accompanying the formation of twins1 are in agreement with the theory outlined in Eq.[l]. Direct observations of the formation of annealing twins at moving grain corners1"3 and the depend-

Jan 1, 1961

By AIME AIME

ON April 7 the twentieth national Open-hearth Conference of the A.I.M.E. will be held in Birming¬ham, Ala., in conjunction with a meeting of the Committee on Blast Furnaces and Raw Materials. At least 300 engineers and operators are expected to attend. Birmingham, the industrial city and iron, and steel center of the South, has been called the "Magic City." Men actively engaged in business in Birmingham today have seen practically every building in the business district erected, have witnessed the establishment of every existing industry, and have hunted birds cm the site now one of the busiest corners of the business district. Incorporated as a town in 1871, the city today has a population of more than 380,000 in its metropolitan area. It is

Jan 1, 1937

By Paul R. Smith

Preparation for flotation begins with dragline mining, pumping, washing, screening, and desliming. Slimes, nominally -150 mesh material, constitute large quantities of phosphate and water which are a disposal problem. Older techniques involve sizing at about 35 mesh for separate coarse and fine treatment. The plus 14 mesh fraction does not require concentration. Coarse treatment includes agglomerate spiralling, belt flotation, thickening, scrubbing with sulfuric acid, de-oiling for reagent removal, and cationic flotation of fine quartz. A recent trend is to screen at coarser than 35 mesh size and eliminate coarse particle treatment, sacrificing some grade of this product. Techniques for flotation concentration of the fine size fraction are discussed.

Jan 1, 1976

By Paul R. Dingess, Edward H. Hare, Douglas C. Brockie

Mining in the Tri-State district of Missouri, Kansas, and Oklahoma has been nearly continuous from about 1848 until the present day, although the major activity was from about 1880 to 1955. The district, which has produced over $2 billion in zinc and lead concentrates, ranks as one of the greatest mining districts in the world. Unlike other Mississippi Valleytype deposits in the United States, which occur in Cambrian and Ordovician limestones and dolomites, the Tri-State district ores occur in Mississippian limestones containing abundant chert. Zinc is 5 to 6 times more abundant than lead. In the Picher Field, the principal sub-district which has accounted for 61 percent of the total district production, most of the ore has been mined from the single horizon, M bed. Most ore bodies, other than those of the "Sheet Ground" or blanket-type, are in large, essentially flat-lying breccia zones and have a definite mineral zonal pattern. An irregular, generally elongated central dolomitic core is surrounded progressively outward by the main ore run, the jasperoid zone, the muddy or shaly and bouldery zone, the sparry calcite limestone zone, and the fossiliferous, dominantly crinoidal, limestone zone. Some of the zones may be absent or nearly so and may overlap to some extent with an adjacent zone. Although the district has been studied by many authors, much controversy still exists about such items as genesis, paragenesis, and time of emplacement. These subjects are discussed in the paper.

Jan 1, 1968

By R. W. Gurry

When a steel in the austenitic state, with all its carbon in solution, is maintained, at constant temperature, in contact with a gas that removes the carbon from the surface, yet without otherwise altering the composition of the steel, the change in weight of the specimen, after any period of exposure, is a direct measure of the amount of carbon it has then lost. The purpose of the present paper is to show how, by application of established mathematical reasoning based on the fundamental diffusion law and on certain postulates, this loss of weight yields a complete picture of the distribution of carbon throughout a specimen of regular shape after any period of exposure, with all the accuracy required in any practical occurrence of decarburization. Precisely the same is true for the gain in weight during the reverse process of carburization, or for the gradual gain or loss of any element, so long as the steel comprises only a single phase at temperature, provided always that the experimental conditions conform to the postulates. The change in carbon content from surface to center of the specimen is always continuous, when everything is in solution, even though under the microscope the decarburized zone (or carburized rim) may appear to be sharply defined. The experimental procedure is described and some typical results are presented, which are then interpreted by application of the diffusion law. Experimental Procedure Initially an endeavor was made to follow the gain of weight during the process of carburization in a hydrogen-toluene atmosphere, but it was soon found that the specimen became coated with graphite, which could not be removed without some loss of metal; therefore it was decided to continue carburization until the steel was saturated throughout, to remove all graphite from the surface of the specimen, and then to follow the loss of weight during decarburization in a moist hydrogen atmosphere at the same temperature as that used for carburizing. The carburizing procedure has been described in an earlier paper;' it suffices to state here that the carburization lasted about I40 hr. at 760°C. (1760°F.) and 44 hr. at iiio°C. (2030°F.), these periods being long enough-—on the basis of the calculations presented later—to ensure that the specimen was about 99.9 per cent saturated at each temperature. The specimen was a cylinder about 3.8 cm. long and 0.475 cm. in diameter; the materials were carbonyl iron, a commercial low-metalloid iron, and a steel with 3.6 per cent nickel and the usual proportion of other elements. The fully carburized specimen, after cooling at the top of the furnace tube, was placed in a lathe and sandpapered to remove all graphite; then the diameter was measured with a micrometer caliper, and the initial weighing (corresponding to complete saturation) was made. By means of a

Jan 1, 1942

By R. W. Gurry

When a steel in the austenitic state, with all its carbon in solution, is maintained, at constant temperature, in contact with a gas that removes the carbon from the surface, yet without otherwise altering the composition of the steel, the change in weight of the specimen, after any period of exposure, is a direct measure of the amount of carbon it has then lost. The purpose of the present paper is to show how, by application of established mathematical reasoning based on the fundamental diffusion law and on certain postulates, this loss of weight yields a complete picture of the distribution of carbon throughout a specimen of regular shape after any period of exposure, with all the accuracy required in any practical occurrence of decarburization. Precisely the same is true for the gain in weight during the reverse process of carburization, or for the gradual gain or loss of any element, so long as the steel comprises only a single phase at temperature, provided always that the experimental conditions conform to the postulates. The change in carbon content from surface to center of the specimen is always continuous, when everything is in solution, even though under the microscope the decarburized zone (or carburized rim) may appear to be sharply defined. The experimental procedure is described and some typical results are presented, which are then interpreted by application of the diffusion law. Experimental Procedure Initially an endeavor was made to follow the gain of weight during the process of carburization in a hydrogen-toluene atmosphere, but it was soon found that the specimen became coated with graphite, which could not be removed without some loss of metal; therefore it was decided to continue carburization until the steel was saturated throughout, to remove all graphite from the surface of the specimen, and then to follow the loss of weight during decarburization in a moist hydrogen atmosphere at the same temperature as that used for carburizing. The carburizing procedure has been described in an earlier paper;' it suffices to state here that the carburization lasted about I40 hr. at 760°C. (1760°F.) and 44 hr. at iiio°C. (2030°F.), these periods being long enough-—on the basis of the calculations presented later—to ensure that the specimen was about 99.9 per cent saturated at each temperature. The specimen was a cylinder about 3.8 cm. long and 0.475 cm. in diameter; the materials were carbonyl iron, a commercial low-metalloid iron, and a steel with 3.6 per cent nickel and the usual proportion of other elements. The fully carburized specimen, after cooling at the top of the furnace tube, was placed in a lathe and sandpapered to remove all graphite; then the diameter was measured with a micrometer caliper, and the initial weighing (corresponding to complete saturation) was made. By means of a

Jan 1, 1942

By W. W. Whitaker, C. W. Manry, R. H. McLean

In an eccentric annulus, cement may favor the widest side and bypass slower-moving mud in the narrowest side. Tendency of the cement to bypass mud is a function of the geometry of the annulus, the density and flow properties of the mud and cement and the rate of flow. Bypassing can be prevented if the pressure gradient protluced from circulation of the cement and buoyant forces exceeds the pressure gradient necessary to drive the mud through the narrowest side of the annulus at the same velocity as the cement. In the absence of buoyant forces, one requirement for this balance is maintenance of the yield strength of the cement greater than the yield strength of the mud multiplied by the maximum distance from the casing to the wall of the borehole and divided by the minimum distance. If the yield strength of the cement is below this value, bypassing of mud cannot be prevented unless buoyant forces or motion of the casing significantly aid the displacement. INTRODUCTION Successful primary cementing leaves no continuous channels of mud capable of flow during well treatment and production. Prevention of channels requires care. Tep-litz and Hassebroek provide evidence of channels of mud after primary cementing in the field.' Channeling of cement through mud in laboratory experiments has also been reported.'-' Recommendations for improving the displacement of mud include (1) centralizing the casing in the borehole,'-" 2) attaching centralizers and scratchers to the casing and moving it during displacement,18 "3) thinning the isolating the cement by plugs while it is circulated down the casing,%( (5 establishing turbulence in the cement," and (6) holding the cement slurry at least 2 lb/gal heavier than the mud and circulating the cement slurry at a very low rate of flow.' Although much has been written about the above parameters, the relative importance of each has not been well defined. In this investigation, the mechanics of mud displacement are described through results from analytical models and experiments. The model chosen — a single string of casing eccentric in a round, smooth-walled, impermeable borehole — is analagous to casing centralized in a borehole which is not round and to placing more than one string of casing in a borehole. In each, some paths for flow are more restricted than others. A fluid flowing in the borehole may seek the least restricted, or most open, path. This tendency for uneven flow can lead to channeling of cement through mud unless preventive measures are taken. The analytical models describe channeling and give means of balancing the flow. Experimental data test the analytical models and illustrate effects of motion of the casing, differences in density and mud's tendency to gel. Results are encouraging. Piston-like displacement of mud by an equal density cement slurry is possible through proper balance of the flow properties of the mud and cement slurries to the eccentricity of the annulus. The more eccentric the annulus, the thicker must be the cement relative to the mud. If proper balance is not achieved. bypassing of mud by cement cannot be prevented without assistance from motion of the casing or buoyant forces. Increasing the rate of flow can help to start all mud flowing but cannot prevent channeling of cement through slower moving mud in an eccentric annulus. Thinning the cement slurry tends to increase channeling although the extent of turbulence in the annulus may be increased. Description of flow in an eccentric annulus begins in the next section. It is assumed that (1) the casing is eccentric and is stationary, (2) the mud and cement slurries have the same density and (3) the gel structure of the mud has been broken and the mud and cement follow the Bingham flow model. Effects related to these restrictions will be discussed. FLOW PATTERNS SlNGLE FLUID IN ANNULUS Flow of a single fluid through an eccentric annulus is illustrated in Fig. 1. Part A shows laminar flow of a Newtonian fluid. This distribution of flow was calculated by Piercy, Hooper and Winney.' In fully developed turbulent flow, the velocity distribution around the annulus is less distorted, but the flow still favors the widest part of the annulus Parts B, C and D of Fig. 1 are a qualitative representation of the flow of a Bingham fluid. The yield strength of the fluid increases the severity of bypassing compared to Newtonian flow. At a very low rate of flow, all flow is confined to that portion of the annulus which has the minimum perimeter-to-area ratio. The fluid shears on the perimeter of that area when the pressure gradient multiplied by the area just exceeds the yield stress of the fluid multiplied by the perimeter. Whether or not the minimum perimeter-to-area region encompasses all of the annulus or only a part (as shown in Part B) depends on the geometry of the annulus. If only a part begins to flow, increasing the rate of flow increases the area flowing until finally there is flow throughout the annulus.

By Karl J. Dreher, Charles C. Hennig, Gregg A. Scott

INTRODUCTION Theodore Roosevelt Dam is a cyclopean-masonry, gravity-arch dam located on the Salt River northeast of Phoenix, Arizona. Construction of the dam began in 1903 and was completed in 1911. The dam is about 85 m high with a total reservoir capacity of about 1.7x109 m3. Raising the dam is now being considered to provide additional water storage and flood control. This paper describes preliminary analyses performed to assess foundation stability for increased loading resulting from raising the dam and reservoir water surface about 12 m. The foundation of Theodore Roosevelt Dam consists of variably metamorphosed limes tones, sands tones, mudstones, and shales. Bedding uniformly strikes nearly normal to the river (N 40º W) and dips upstream at 25 to 30º. The rock is cut by four prominent joint sets as indicated by the joint contour diagram shown in figure 1A. The diagram was developed from surf ace observations and vertical drill core oriented relative to the bedding. Sampling biases account for the differences in concentrations of various joint sets. However, field observations indicate that all sets are relatively prominent, planar, and continuous. SEEPAGE ANALYSES Consistent with practice at the time of construction, no foundation drainage was installed at Theodore Roosevelt Dam. Finite element seepage analyses were therefore performed to study the potential for large uplift pressures in the foundation. The dam has steep abutments and is curved in plan as shown in figure 1B. The effects of modeling the seepage two-dimensionally, radially symmetric about the dam's axis center, and three-dimensionally were therefore com-

Jan 1, 1982

By William E. Ford, Edward Salisbury Dana

In their action upon the senses a few minerals possess taste, and others under some circumstances give off odor. 444. Taste belongs only to soluble minerals. The different kinds of taste adopted for reference are as follows: 1. Astringent: the taste of vitriol. 2. Sweetish astringent: taste of alum. 3. Saline: taste of common salt. 4. Alkaline: tast'e of soda. 5. Cooling: taste of saltpeter. 6. Bitter: taste of Epsom salts. 7. Sour: taste of sulphuric acid.

Jan 1, 1922

By Roshan B. Bhappu, Ronald J. Roman, Dexter H. Reynolds

The reaction between manganese dioxide and molybdenite in a water- sulfuric acid medium was studied at atmospheric pressure and from 25° to 103°C. Both solids are dissolved to give, as final products in solution, Mo(VI), S(VI), and Mn(II). Stoichiornetric relationshifis are most simply represented by the equation MoSz + YMnO2 + 15H+ - HMoO-4 + 2HSO-4 + 9Mn++ + 6H20 The rate of this reaction was found to be dependent on temperature, manganese sulfate concentration, acid concentration, and, in a complex way, the surface areas of both manganese dioxide and molybdenite. Both the total amount of manganese dioxide and tnolybdenite and the ratio of manganese dioxide to molybdenite played a part in determining the over-all rate of the reaction. The effect of acid concentration on the rate was also dependent on the ratio of manganese dioxide to molybdenite. SEVERAL reports in the literature describe reactions using manganese dioxide in water-sulfuric acid media as an oxidizing agent. Nearly all previous work describes interactions between an ion and manganese dioxide, such as the oxidation of ferrous to ferric iron,' or the interaction between a molecule in solution and manganese dioxide, such as the oxidation of toluene to benzaldehyde.2 Only a few references describe the use of solid manganese dioxide to oxidize another solid in sulfuric acid. One report3 states, "Manganese dioxide in dilute sulfuric acid solutions had no beneficial effect (in leaching copper from chalcopyrite), but in more concentrated acid solutions the rate of solution was about the same as that for permanganate." In 1902 a German patent4 described a process which used manganese dioxide in strong (50°Be') sulfuric acid for oxidizing chromite ores to soluble iron and chromium salts. The process consisted of mixing the sulfuric acid with the finely ground ore and manganese dioxide. The pulp was then heated to about 120°C and an electric current passed through it. The manganese dioxide apparently dissolved in the strong, hot acid solution, oxidized the iron and chromium and itself was reduced to manganese 11! then was oxidized at the anode back to manganese dioxide, and the cycle repeated. An extensive study5 of the kinetics of the oxidation of pyrite with manganese dioxide indicated that in dilute sulfuric acid solutions (about 0.1 N) and at elevated pressures the dissolution of the pyrite was brought about by air oxidation of the iron to ferrous sulfate, followed by manganese dioxide oxidation of the ferrous sulfate to ferric sulfate. The mechanism proposed by the authors involved the oxidation of the iron at the surface of the manganese dioxide. Also! the oxidation of sulfide sulfur to sulfate was credited to the oxygen in the air, not to the manganese dioxide. Since the metallurgical literature is lacking in information concerning the use of one solid to oxidize another solid. the current investigation was under-

Jan 1, 1965

By I. Milton LeBaron

Operation of the phosphate flotation plant at the Peace valley mine of the International Minerals and Chemical Corporation, Florida, began in the summer of 1942. Since that time several changes have been made in the flowsheet, with resultant increases in metallurgical results. Three flowsheets, together with the comparative plant results, are given in this paper, together with a discussion of the desliming circuit used for preliminary washing of the flotation feed. Fig. I lists the essential units in the original flowsheet at the Peace Valley plant. The figures for tonnage and grade are average for a period of two months. Mineral Separation Airflow cells are used for both the fatty acid and the amine float. Three immediate difficulties presented themselves in the use of this flow sheet: I. Floating a maximum amount of phosphate in the rougher section to give good recovery sent a low-grade concentrate to the silica float, resulting in high costs for amine reagent in that section.

Jan 1, 1947

By I. Milton LeBaron

Operation of the phosphate flotation plant at the Peace valley mine of the International Minerals and Chemical Corporation, Florida, began in the summer of 1942. Since that time several changes have been made in the flowsheet, with resultant increases in metallurgical results. Three flowsheets, together with the comparative plant results, are given in this paper, together with a discussion of the desliming circuit used for preliminary washing of the flotation feed. Fig. I lists the essential units in the original flowsheet at the Peace Valley plant. The figures for tonnage and grade are average for a period of two months. Mineral Separation Airflow cells are used for both the fatty acid and the amine float. Three immediate difficulties presented themselves in the use of this flow sheet: I. Floating a maximum amount of phosphate in the rougher section to give good recovery sent a low-grade concentrate to the silica float, resulting in high costs for amine reagent in that section.

Jan 1, 1947

By G. R. Rubly, H. J. Steele

LOCATION AND HISTORY THE San Manuel property is in townships 8S and 9S, range 16E, Gila and Salt River Base and Meridan, State of Arizona. This area is in the Old Hat mining district, southern Pinal County, and is about 3;2 miles southwest of the town of Mammoth on the San Pedro River and one mile south of the Mammoth mine at Tiger, Arizona. The property consists of over 150 contiguous lode claims. The Old Hat district was prospected prior to the Civil War, but there was little or no production until 1881.1 The chief producers have been the Mammoth and Mohawk mines, now consolidated and operating as the St. Anthony Mining and Development Co., Ltd. Production to 1936 was $5,200,000, of which 83 pet was gold.2 Since 1940 the production has been chiefly lead and zinc, and some molybdenum and vanadium. There are a few small properties in the vicinity that have produced very minor tonnages of copper ore. In the San Manuel group there are claims which have been held continuously from 1906 to the present time, and at least two churn-drill holes were put down on or near the outcrop in 1917. No logs for these holes are available, but it is assumed that the grade of copper encountered was not sufficient to encourage further exploration. A small amount of ore has been shipped from open cuts on the San Manuel outcrop area, but there is no record of the tonnage or grade. It is estimated that not more than 5o tons were mined. These cuts, plus a few shallow shafts and some short adits indicate limited and unenthusiastic prospecting at San Manuel. In 1942, through the efforts of James M. Douglas, R. B. Giffin, Victor Erickson, and Henry W. Nichols, owners of the San Manuel group, the Reconstruction Finance Corporation and War Production Board authorized the United States Geological Survey to investigate the property, and by their recommendation, the United States Bureau of Mines was authorized to put down a limited number of churn-drill holes. The Bureau of Mines carried on drilling from November 1943 to February 1945. Seventeen holes were drilled, varying from 305 to 1990 ft in depth. The property was brought to the attention of Magma Copper Co. in June I944 and an option agreement was made with the owners. Subsequently, a group of claims lying north of the original group and held by the Apex Lead Vanadium Mining Corp., and a group to the east held by the Quarelli family, were optioned. A drilling program was laid out to conform to the Bureau of Mines pattern, and drilling started in December 1944. San Manuel Copper Corp. was incorporated September 1945, and has carried on the exploration program to the present time. GEOLOGY General The mineralized outcrop, chief copper mineral of which is chrysocolla, is a tri-

Jan 1, 1947