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By Henry N. Toler

Development in the Jackson gas field, Hinds and Rankin counties, for 1935 continued at a slow pace, there being only nine wells drilled on the structure, of which five resulted in gas producers and four in dry holes. There were no wells drilled deep enough during 1935 to test any of the horizons below the producing Selma chalk. There are 113 producing gas wells in the Jackson gas field, with three wells on the southeast edge of the field making some oil with a large quantity of salt water; this oil comes from the same horizon as the gas. The combined open flow of the 113 gas wells is about 4,100,000,000 cu. ft. The proven area of the field is approximately 8000 acres. The production of 10,291,000,000 cu. ft. for 1935 represents the largest yearly pull from the field by almost a billion cubic feet. The total production from the field to date is 45,104,000,-000 cu. ft. It is interesting to note that the rock pressure has dropped from 1010 lb. per sq. in. initial to 943 Ib. at the end of 1935, a decline of only 67 lb. in 6 years. There is a difference of opinion as to the age of the deepest formation tested on the Jackson structure; some people holding that it is Tuscaloosa, others, Trinity, and still others that it is Paleozoic, probably Pottsville. The production of the Amory gas field, Monroe County, continued to decline and the capacity was far under the demand. Originally there were four producing wells in the field with a combined open-flow capacity of approximately 15,000,000 cu. ft. and a rock pressure of 680 lb. per sq. in. At the end of 1935 only two wells were producing with a combined open-flow of less than 1 million cu. ft. and the rock pressure down to 100 lb. or less. No attempt has been made to drill new wells in the immediate field but three wells are being drilled in the county in an effort to secure new supplies of gas. The wildcat operations for 1935, with only 11 wells drilled, were the lowest since 1932, just about one-half the number drilled during 1934. None of the wildcat wells drilled in 1935 resulted in producers and, so far as the writer is aware, did not uncover any large structures. The 11 wells drilled were abandoned or junked at comparatively shallow depths, except the well drilled in George County to 6928 ft. by the United Gas

Jan 1, 1936

By Charles Clayton

IN connection with certain coöperative work carried on between the Ordnance Department of the U. S. Army, the U. S. Bureau of Mines, and the U. S. Geological Survey during the year 1918, it was the writers' privilege to make metallographic examinations of a great many test bars and other pieces of nickel-steel gun forgings. The material studied came from many different steel plants throughout the country and consisted both of forgings that had been accepted by the Ordnance Department and those that had failed to pass the specified physical tests. In general, these tests require a minimum tensile strength of 95,000 lb. (42,091 kg.), an elastic limit of 65,000 lb. (29,483 kg.), an 18 per cent. elongation, and a 30 per cent. reduction in area. An average chemical composition of the steel studied is 0.38 per cent. carbon and 2.9 per cent. nickel. The steel was of both basic electric and basic open-hearth manufacture. The object of the metallographic work was two-fold: to assist in detecting defects in the steel and, if possible, to suggest remedies for the same; and to obtain as much information as possible in regard to the relation of the microstructure of the metal to its physical properties. The greater part of the investigation was devoted to defective metal that failed to pass the ordnance specifications. Many types and kinds of more or less serious defects thus came under observation, but most of these were due to the attempts by the manufacturer to meet the enormous demand for ordnance steel with more or less inadequate equipment, and were soon remedied. Two defects, the so-called "flakes" or "snowflakes" and a certain "fibrous" or "woody" fracture, were encountered so frequently and were so disastrous to the steel that the greater part of the study was devoted to them. As a result much information as to their nature and their effects

Jan 2, 1919

By John A. Hansuld

Molybdenum presents a series of baffling geo- chemical puzzles. It can exist in six different valence states, possessing three different coordination numbers. As a result, it combines with other elements to form a wide variety of negatively and positively charged ions and complexes whose exact chemical nature are relatively unknown. Its rather complex chemistry might be described as "ambidextrous, bi-sexual and polygamous". It is little wonder then that the geochemistry of molybdenum is relatively unknown, and compared to most common metals its geochemical behavior is somewhat unique. The behavior of a particular element or metal, such as molybdenum, in a given dispersion media is largely controlled by the stability relations among its various oxidation products. Recognition of these products and an understanding of their stability relations is therefore a prerequisite to a proper understanding of its observed behavior. Because most secondary dispersion media represent aqueous chemical systems, stability relations are best expressed as functions of Eh and pH.

Jan 12, 1966

By D. D. Pollock, G. P. Conard II

Equations of the form of the Mott and Jones equations for the absolute thermoelectric powers of metals are derived primarily from a thermodynamic approach. The behaviors of transition thermoelements in common use are then examined and compared with this simple theory. MOTT and ones' derived a general expression for the absolute thermoelectric behavior of metals and alloys using the approach of the solid state physicist. This expression was then applied to specific cases.1,2 The present work develops equations of the same form principally by a thermodynamic approach. These relationships are then employed to gain some insight to the behavior of the transition thermoelements in common use. I) DERIVATION OF AN EXPRESSION FOR ABSOLUTE THERMOELECTRIC POWER First consider a metallic conductor which is maintained in a temperature gradient with no current flowing. At constant pressure, there will be a gradient of the free energy (F,) given by:

Jan 1, 1963

By F. S. McNicholas

IN the first big blast at Climax, a "loop back" (three-wire system) was used (Fig. 1), with the idea of securing a wiring system that would give to all series the same amount of current. Single-phase, 60-cycle, 13,800-volt FIG. 1.-Loop BACK. A THREE-WIRE SYSTEM WITH BRANCHES VARYING IN LENGTH. power was furnished to the blasting transformers, each of which has a rated capacity of 600 amp. at 480 volts. Two blasting leads were taken from these transformers, giving a blasting current of single phase, 60 cycle, 480 volts, with an instantaneous capacity of more than 600 amp. The blasting switch was on the secondary leads from the transformers, to avoid lag in energizing them.

Jan 1, 1938

By Alfred H. Bell, George V. Cohee

In 1939 Illinois produced 94,302,000 bbl. of oil—almost three times the amount of oil produced at the peak in 1908, when development in the southeastern Illinois field was at its height (Fig. I). It represents nearly a fourfold increase over the 24,075,000 bbl. produced in 1938 (Table 6). This rapid increase in oil production in Illinois is largely due to development in the Salem and Louden fields (Table I). During 1939 daily production for the state increased from 135,000 to 332,572 bbl. A notable increase in production for 1940 is expected as a result of the drilling of the Devonian limestone in the Salem and Centralia fields,

Jan 1, 1940

By Alfred H. Bell, George V. Cohee

In 1939 Illinois produced 94,302,000 bbl. of oil—almost three times the amount of oil produced at the peak in 1908, when development in the southeastern Illinois field was at its height (Fig. I). It represents nearly a fourfold increase over the 24,075,000 bbl. produced in 1938 (Table 6). This rapid increase in oil production in Illinois is largely due to development in the Salem and Louden fields (Table I). During 1939 daily production for the state increased from 135,000 to 332,572 bbl. A notable increase in production for 1940 is expected as a result of the drilling of the Devonian limestone in the Salem and Centralia fields,

Jan 1, 1940

By M. A. Olade

Biotite, magnetite and quartz feldspar separates from rocks around porphyry copper deposits in the Highland Valley have been analyzed for copper, zinc and other related trace and major elements. Results show high copper concentrations in mineral samples close to mineralization, with a strong positive correlation with whole-rock copper contents. Zinc, on the other hand, shows no cleat-cut systematic relationship to mineralization, although there is a subtle decrease in the dues obtained for anomalous biotite samples. Manganese, cobalt and nickel in biotites show similar patterns as zinc. Using a sulfide-selective leach, it is show that the enhanced copper dues in mineral samples proximate to mineralization can be accounted for by the presence of minute inclusions of sulfides. In contrast zinc seems to occur in isomorphous substitution for femic elements, in a form that is leachable by hydrothermal activity. Results also show that copper content of biotite has a positive correlation with the modal proportion of biotites and their iron contents, whereas a negative relationship with manganese is apparent Geochemical contrast for copper between background and anomaly is not better in mineral fractions than whole rocks, consequently the use of minerals as sampling media shows no obvious advantage for mineral exploration purposes in the Highland Valley district.

Jan 9, 1979

By Carl H. Beal

DURING the latter part of 1915 and the first half of 1916, the writer held the position of geologist in connection with the conservation work instituted by the U. S. Bureau of Mines, on oil and gas land belonging to the Indians of the Five Civilized Tribes in Oklahoma. The duty of the geologist was to correlate formations containing oil, gas, and water, and to determine the relations of these substances in the different formations so that the conservation agents might carry on their work most intelligently. On account of the rapid development of the Cushing field, which lies in the western part of the Creek Nation, much work was done there by the inspection force. In the course of the geologic studies a large amount of information was collected, which, on analysis, has disclosed some interesting facts worthy of publication. The report, of which the following remarks are an abstract, has been prepared and submitted to the U. S. Geological Survey for publication. This report is now (June, 1917) in the press and will doubtless be issued in a few weeks. Methods Used In addition to the structure maps showing the folding of the Pawhuska limestone, which crops out in several places in the Cushing field, separate structure maps of the three most important productive sands—the Lay-ton (Fig. 2)) Wheeler, and Bartlesville—have been prepared. These structure maps were prepared by obtaining the logs of nearly all the wells

Jan 1, 1918

By Ronald W. Klusman, Erik B. Nelson

The Front Range portion of the Colorado Mineral Belt is an extensive area of mineralization with mining activity dating from 1859 with the discovery of large gold deposits. After an initial boom period and gradual diminishing production, present activity is restricted to molybdenum in Clear Creek County, uranium in Jefferson County, and several small operations extracting gold and silver in Clear Creek and Gilpin Counties. Gold and silver have dominated the production in the Front Range, though the complex mineralization created milling and smelting problems and it is postulated that considerable amounts of precious metals remain in the mine dumps. This area is plagued by a severe mine drainage problem, with Clear Creek most impacted by many draining mines and tailings in the basin. Boyles et al. Moran and Wentz, Wentz, Wildeman et al., have examined various aspects of the impact of mine drain¬age in the Clear Creek basin. The primary objective of this study was to collect data on the tailings, drainages, and leaching experiments in order to make preliminary suggestions for reducing the impact while recovering metal values to offset treatment costs. A variety of leaching experiments were performed on tailings from the Nevada Gulch area in the Central City mining district. Leachings were performed in vertical tubes indoors and wooden boxes exposed to the outside environment. In the leaching experiments, the leaching solution, grain size, and residence times were varied, while forced aeration was used in some experiments. Bacterial nutrient 9K° and mine drainage were used in some of the experiments. A total of 14 additional tailings samples were analyzed for base and precious metals. The composition of the mine drainage and tailings used in the leaching experiments, as well as data on the additional samples are shown in [Table 1]. Leachate samples were taken periodically for analysis until compositions leveled off. Results and Discussion Leaching with distilled water was used as a control and best illustrates the basic behavior of the leaching process for zinc in a vertical tube [(Fig. 1)]. More acidic leachings increased concentrations of metals as did smaller grain sizes, though the time required increased significantly. Mine drainage with its high concentration of dissolved iron sometimes decreased the heavy-metal concentration in the leachate due to oxidation of Fe 2 and precipitation of Fe(OH)9 which absorbs some of the dissolved heavy metals. In the larger scale experiment carried out in the simulated leaching pad, substantial concentrations of metals were attained in the final leachate after one month. In this experiment the leachate was not recycled, but allowed to saturate the tailings continually with evaporation loss made up by additions of Quartz Hill drainage and nutrient 9K. The concentration of the metals in the leachate and the increase over the input solution are given in [Table 2]. Heap leaching of low-grade copper and uranium ores is successfully carried out in many districts, enhanced by the metabolism of autotrophic bacteria of the Thiobacillus-Ferrobacillus group. These ubiquitous organisms enhance metal leaching, and general aspects of heap leaching are discussed by Malouf, Trudinger, Pings, and Duncan et al. Conclusions and Recommendations Returning to the primary objective, how to reduce the mine drainage impact and recover metal values, we need to consider how the data may suggest avenues toward this objective. Boyles, et al., considered various

Jan 1, 1977

By P. Payson

Intergranular corrosion in corrosion-resistant chromium-nickel steels has been widely discussed in the last few years. So far as the author knows, nothing has been published which definitely shows that this tendency can be eliminated, although suggestions have been made that a remedy is possible if certain specifications are satisfied. Strauss, Schottky and Hinnüberl suggested an increase in chromium content to an extent that would prevent the impoverishment of chromium on carbide precipitation sufficient to cause impaired corrosion resistance in the matrix. Pilling2 suggested an increase in nickel, so that the stability of the austenite matrix would be increased. Aborn and Bain3 say that "intergranular attack—may be eliminated by preventing carbide precipitation (e. g., by lowering the carbon content or somehow raising its solubility) or by precipitating it permanently under conditions which will not remove chromium from solid solution so drastically at any points." In a later paper Aborn and Bain4 state that many different metallic elements, tungsten, vanadium, copper, aluminum, molybdenum, titanium and zirconium, have been added in small percentages to increase the stability of these alloys, but that it has been reported that according to the copper sulfate test these added elements act only to retard the intergranular corrosion. and that increased nickel and chromium contents have similar effects. Newell5 showed that the lower the quenching temperature before reheating, the less severe was the intergranular attack.

Jan 1, 1932

By Thomas F. Bates

ANALYSIS of the chemical and structural differences in minerals often results in a better understanding of the differences in the geological conditions under which they were formed. The minerals in the kaolinite group differ in the amount of interlayer water and in the nature and amount of ordered and/or random shifting of each 1:1 layer with respect to those above and below it. This paper is a progress report resulting from research on the morphology, structure, and origin of fine-grained minerals, supported by Contract N6onr26914 with the Geophysics Branch of the Office of Naval Research. The purpose of the paper is to present data obtained in the laboratories at The Pennsylvania State College and elsewhere, which reveal some of the details of structure of the minerals in the kaolinite group, and to suggest a number of interpretations that bear upon the conditions of origin of these minerals. Be¬cause most of the work in this investigation thus far has been concerned with the relationships of kaolinite, halloysite (4H2O; endellite), and halloysite (2H2O), must of the discussion deals with these members of the group. The first step in the analysis of the differences in two sets of geological conditions is an evaluation of the differences in the minerals that result. Thus the chemical differences between the montmorillonite and the kaolinite clays corroborate other evidence in support of the view that the montmorillonites are commonly formed when solutions are alkaline and leaching poor, while kaolinite usually is associated with acid solutions and good drainage condi¬tions. It is obvious that the greater the differences in the minerals, the more divergent may be the conditions that give rise to them and the more readily one condition can be distinguished from the other. In the kaolinite group, differences between individual members are small, therefore the differences in condition of origin are presumably subtle and difficult to define. At the same time, the very fact that the minerals differ only slightly makes them more sensitive indicators of the exact conditions under which they and the minerals associated with them were formed. Since clay minerals are being used more and more to evaluate the nature, value, and mode of formation of economic mineral deposits, an attempt to define these subtle differences would appear worth while. For purposes of the present discussion, the minerals nacrite, dickite, kaolinite, the so-called "fireclay mineral," halloysite (4H2O), halloysite

Jan 1, 1952

H. 0. HOFMAN, Boston, Mass (written discussion*).-The paper by Mr.. Pyne gives clear evidence of the difficulties the metallurgist is likely to encounter when he tries to recover in the blast furnace the metal from old chromite lining used as a refractory material in the copper reverberatory furnace. It appears that chromite cannot be fluxed at temperatures which usually prevail in copper blast furnaces. This calls to mind the freezing-point curve drawn by M. Simonis1 of mixtures of chromite and kaolinite. The chromite used in the experiments contained 52.9 per cent. Cr203, 22.6 FeO, 4.8 AI203, 9.6 Si02, .10.1-MgO; FIG. 1. the kaolinite was clay from Zettlitz with 98.5 per cent. clay-substance: The accompanying curve shows that the eutectic mixture with 35 per cent. kaolinite and 65 per cent. chromite freezes at Seger cone No. 15 (1435° C.), while kaolinite fuses at cone No. 35 (1770° C.) and chromite at cone No. 42 (2000° C.). The curve indicates that the difficulty in the blast furnace can be overcome by having at the smelting zone a temperature much higher than is usual in copper smelting; a charge composition similar to that prevailing at the Mansfeld copper smeltery -which gives with 23 per cent. coke a, slag of the composition Si02, .49.09; .(FeMg)0, 5.58; (CaMg)0, 16.02; A1203,-16.02-might flux and fuse chromite.

Jan 3, 1918

By Walter H. Bruckner, George B. Clark

SINCE the end of World War II interest has been increasing in the use of shaped charges in the mining industry and in other industries using explosives for blasting purposes. Shaped charges employ the principle known as the "Munroe effect," which was discovered by Charles E. Munroe more than 50 years ago (in 1888). Details of their design have been explained e1sewhere.l,2,3 Fig I shows the essential features of design of two types of shaped charges (with conical and hemispherical cavities) and a schematic sketch of their action upon detonation. The following discussion deals with the behavior of the metal in the cavity liners when they are subjected to intense pressures exerted when the explosive charge is detonated. Among the conclusions reached in research on shaped explosive charges, the following have been established concerning cavity liners: 1,2 I. The optimum wall thickness of a conical cavity liner is dependent upon the apex angle of the cone as well as on the base diameter of the charge. Acute apex angles require thinner walls for optimum performance and more obtuse angles require thicker walls for the same base diameter. 2. Cones were more effective in forming a penetrating jet when the walls were tapered; i.e., the thickness of the wall of the cone increased from the apex down. 3. The physical and mechanical proper- ties of metals have a marked effect upon their performance as cavity-liner material. Boiling point, ductility, malleability, tensile strength, and hardness are among the properties that influence the effectiveness of a metal used as a cavity liner. Lead, for example, makes a wide, flat crater in steel plates. Aluminum makes a deeper crater than lead, and an aluminum alloy having a high tensile strength makes a deeper hole, but slightly smaller in diameter. Cast iron makes a deep, narrow hole. These findings, together with the following analysis under Metallographic Survey of Slug, offer solutions to many of the problems involved in solving the mechanism of the formation of Munroe jets. It has been fairly well established that cavity liners collapse in a manner similar to that indicated in Fig 2. Conical liners are known to collapse upon themselves while hemispherical liners are believed to turn inside out in the process of jet formation. The first has been definitely proved by recovery of collapsed portions of cones, while liners from partly detonated charges show that hemispheres may turn inside out. Fig 3 shows a sketch of a recovered slug from a 6-in. shaped charge using a 45° cone made of cast iron. (This size of charge drilled holes up to 3 ft in depth in solid granodiorite.)

Jan 1, 1947

By R. Schuhmann, O. W. Moles

at temperatures of 1150°, 1250°, and 1350°C for liquid copper sulphides ranging in composition from saturation with Cu to about 21.5 pct S. From the experimental data, activities of Cu, S, and Cu2S in the melts were calculated. Also, the results furnish a new determination of the location of the curve showing the compositions of Cu-saturoted sulphide melts in the CU-S constitution diagram. THE "white metal" made as an intermediate L product in converting copper matte to blister copper is a matte approximating Cu2S in composition. It has long been known that liquid Cu-S mattes can exist at a given temperature over an appreciable composition range, with S:Cu ratios ranging up from a lower limit corresponding to equilibrium of the matte with a liquid Cu phase. The Cu-saturated matte has somewhat less S than Cu2S, although previous measurements of the compositions of Cu-saturated mattes are not in good agreement.'" As the S:Cu ratio approaches and slightly exceeds that for Cu2S, the partial pressure of sulphur gas over the liquid matte rapidly approaches atmospheric pressure,5 so that Cu-S melts with much more S than Cu2S can be made and handled only in pressure apparatus. Accordingly, the liquid copper sulphides of interest in copper smelting and readily studied experimentally fall in a relatively narrow composi- tion range about Cu2S. The freezing points of Cu-S mattes show a maximum of 1129°C near the composition Cu, dropping to 1105oC for Cu-saturated mattes having less S and dropping under 1100°C for higher S mattes.' Estimates of the sulphur pressure and other thermodynamic properties of liquid Cu,S were made by Kelley; based on extrapolations from equilibrium measurements on solid Cu,S. More recently, Cox and coworkers' studied equilibria in the reaction: Cu,S + H, e 2Cu + H,S over the temperature range 700" to 1250°C. They measured equilibrium H2S:H2 ratios presumably with both the sulphide and the metal phase present, so that their data above the melting point of Cu,S should measure the S pressure of Cu-saturated sulphide melts. The sulphur pressures of liquid copper sulphides of several S:Cu ratios at their freezing points can be estimated from data given by Posnjak, Allen, and Merwin." However, beyond these few data, no systematic study seems to have been made of the relations of sulphur pressure and other chemical properties of liquid copper sulphides to composition and temperature. The measurements of the sulphur pressures of liquid copper sulphides reported in this paper represent a first step in the quantitative study of the chemistry of mattes. Similar work is planned on

Jan 1, 1952

By R. W. Raymond

There is apparently no end to the doubts, inconsistencies and absurdities in which the courts of our mining States and Territories are involved in their attempts to apply to conditions of ever-increasing complexity the provisions of our anomalous mining law. In previous papers, I have called this statute " the law of the apex," because it based upon that vague, novel and mysterious condition the most important grant of title. But the apex is scarcely a more essential feature than the end-lines and the side-lines; for the rights which it may confer may be limited in various ways by these; so that we have, in many a case, the most ridiculous result that the United States, in return for the money of a citizen, conveys to him with much solemnity, under its broad seal, nobody knows what, bounded nobody can tell how. A decision recently made at Butte by Judge De Wolfe, of the United States District Court of Montana, in the case of King et al. vs. The Amy and Silversmith Mining Company, furnishes a fresh illustration of this criticism. The diagram on the following page, constructed without precise regard to courses and distances, simply to assist in the statement of the essential features of the case, will, 1 hope, make clear the principles . involved : The plaintiff occupies a location (the Nonconsolidated) adjoining on the north the defendant's location, a b c d (the Amy), and the disputed mining-ground lies, let us say, in depth under the point W, that is, on the dip of the vein, VD, but not under the surfacelocation, a b c d. The defendant has the prior title, and claims this ground under its extra-lateral right. It is admitted that the apex does not cross the end-line, a d, and does cross the side-line, a b. Whether it crosses, at the other end of the location, the end-line, b c

Jan 1, 1889

By R. B. Hoy, Stanley J. LeFond, K. Reckling

World production of natural diamonds prob¬ably exceeds 50,000,000 carats a year. The Republic of Zaire is the leading producer, with an output which is primarily industrial rather than gem grade. The USSR ranks second, and the Republic of South Africa third. Diamonds are also mined in South-West Africa, Angola, Ghana, Sierra Leone, and other African coun¬tries. In the western hemisphere, Brazil and Venezuela are the principal producers (Fig. 1). A very small output of diamonds is mined today in India, which was the first source of commercial production. In the U.S., efforts at commercial diamond mining have been con¬fined to a small area near Murfreesboro, Ark. The first diamond was found in a kimberlite pipe there in 1906. Small-scale trial mining has not, however, proved economical. Since diamonds were first discovered over 2000 years ago, only about 130 tons have been mined. In order to obtain 1 g (5 carats) of diamonds, it is necessary to remove and process approximately 25 tons of rock. Recovering this small percentage involves a combination of highly developed techniques in mining, quarrying, and earth-moving, and extremely sophisticated recovery processes. End Uses Diamonds are used for two unrelated end uses; gem diamonds are jewels of great beauty while industrial diamonds are essential ma¬terials of modern industry. Although imitation stones are substituted for the gem diamond, none of these matches its properties sufficiently well to offer real competition. Synthetic indus¬trial diamonds are now of a quality that per¬mits wide substitution in the fine-grained sizes. Gem Diamonds A diamond is a natural prism. It has the ability to bounce light rays (reflection), to bend them (refraction), and to break them into all colors of the rainbow (dispersion). This ability to "modify" light gives the diamond three characteristics for providing beauty. First is brilliance, the reflection of light back to the eye. Second is fire, dispersion of light into the colors of the spectrum. Third is scintillation, the "twinkling" that occurs when the diamond is moved (Bauer, 1969). The skill of the diamond cutter is required to unlock the brilliant, fiery beauty of a gem dia¬mond (Fisher, 1966). Diamond-cutting skills have gradually developed over the centuries. The first cutters, in India, learned how to grind one rough diamond against another to remove their "skins" and to give them various shapes. This revealed some fire and beauty, but little compared to that of the diamonds that are cut today. About 1475, a Flemish cutter named Van Gerquem discovered that diamond dust on an iron wheel would polish facets on a diamond to provide more brilliance and fire. Cutters continued to experiment with facets, and shortly before 1700 a Venetian cutter named Peruzzi developed the 58-facet brilliant cut. With the development of the science of optics, cutters have learned more about the behavior of light within the diamond. Early in the 20th century, they learned how to angle Peruzzi's

Jan 1, 1975

By Frederick L. Knouse

THE south border of Espirito Santo begins about 400 km. north of Rio de Janeiro and extends along the Atlantic Coast northward some 325 km. and inland 100 to 150 km. The area under consideration, where quartz crystal of strategic grades has been mined, extends from 19° to 21° and 30" south latitude; and from 40° to 41° and 30" west longitude. This includes the central part of Espirito Santo, chiefly south of the Rio Doce from the Atlantic ocean, and west across the border into Minas Gerais near the town of Aimores, in the municipalities of Aimores, Minas Gerais; Baixo Guandu, Santa Teresa, Santa Leopoldina, Colatina, Joao Neiva, Fundao and Domingo Martines, Espirito Santo (Fig. 1). During 1943 and the first half of 1944, this region accounted for approximately 3 to 5 per cent of the quartz crystal produced in Brazil. Shipments of crystal have been made chiefly by rail to Rio de Janeiro. This region is serviced by the E. F. Minas-Vitoria and E. F. Leopoldina to Rio de Janeiro through Vitoria; and by the E. F. Minas-Vitoria and E. F. Central do Brasil through Bello Horizonte, Minas Gerais to Rio de Janeiro. The major deposits are accessible from the railheads by dirt roads, some being 5 to 30 km. off the road, reached by trail. In 1943 and the first half of 1944, the bulk of the production was from inter mountain marshes and adjoining hillside alluvial placer deposits in the zone surrounding the town of Santa Teresa. Most of these deposits were formed from the erosion of pegmatites, quartz veins and pockets in the gneiss, with minor quantities produced from miarolitic cavity fillings in the granitic rock. EARLY OPERATIONS Mining of quartz crystal in this region began in 1928, and has been stimulated by the market demand for military uses. Before 1936 little attention was given to it, either in Espirito Santo or eastern Minas Gerais. From 1936 to 1941 the Japanese sent agents to various points of production or potential production to acquire quartz through purchase. They bought crystal as small as 10 grams. Since 1941 only the United States and Great Britain have received quartz from Brazil. The United States purchases crystals of loo grams and larger for strategic purposes. The first known discoveries were made either in the municipalities of Aimores, Minas Gerais, or in Baixo Guandu, or Domingos Martines, Espirito Santo. Marketable quartz crystal was first found either in the massive quartz replacement veins of the Victor Hugo mine in the municipality of Domingo Martines, or in the large cores of quartz in the pegmatites near Baixo Guandu, extending into Minas Gerais. PRODUCTION The production of quartz in Espirito Santo from 1936 through 1941 as recorded

Jan 1, 1946

By Reinhardt Thiessen

Under sulfur in coal, is usually understood that form of sulfur which is combined with iron and known as pyrite. It occurs in the form of balls, lenses, nodules, continuous layers, thin sheets, or flakes, both in horizontal planes and vertical cleavage fissures. But pyrites also occur as very fine microscopic particles, or nodules, disseminated through the compact coal. This form has had but very little consideration. Finally, there is sulfur in coal in an amicroscopic form (not visible with an ordinary microscope), probably combined with the organic matter that exists in the coal. This form has had considerable attention from a scientific standpoint, but has probably not been recognized enough on the economic side. One or the other, or both, of these two latter forms may comprise the larger part of the sulfur content of coal, especially after it has been washed or otllerwise prepared for use. Pyrites in Microscopic Particles All coals that have been examined by the author contained a varying amount of sulfur in very small globules, or particles, of pyrite. These particles are seen in a thin [section as roughly rounded opaque dots, Figs. 1 to 10. When isolated, they are generally shown to be approximately spherical in shape, with a rough outer surface. They vary in diameter from a few microns to a hundred microns, the majority messuring from 25 to 40 microns; relatively few exceed the latter diameter. They are, therefore, very small objects. Their size is best appreciated by comparing the illustrations, in which they are shown. at a magnifiea tion of 100 diameters, with some known area like the period used in the ordinary printed page. The period is about 0.6 mm. in diameter, and . when magnified 100 times, will cover a circular area of about 2 1/2 in. in diameter, or all but the corners of the illustrations. The illustrations, therefore, represent an area about as large as an ordinary period, and the pyrite globules form but a small part of the total area. Very frequently a number of these particles are joined together in horizontal rows; oc-

Jan 1, 1920

By David H. Y. Tang, Syd S. Peng

In general, the strata sequence of the immediate roof in the under- ground coal mine openings can be divided into three types. They are: (A) each stratum deflects independently, (B) some stratum (or strata) loads on the underlying stratum, and (C) each stratum loads on its underlying stratum. The flexural behavior of the immediate roof which is made up of multiple strata not only depends on the material property, geometry, and external loading of rock strata, but also on the strata sequence. A computer program based on the beam-column theory is written for determining the bending stress and deflection for the generalized immediate roof. The flexural behavior of the immediate roof in various strata sequences are investigated for the following effects: roof span, horizontal stress, thickness and Young's modulus of the lowest stratum. In addition, some of the results are compared with the results of the finite element method.

Jan 1, 1983