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By Charles A. Schffer

Several months ago, some specimens of the minerals occurring at the Etta tin mine, Dakota, were received at the laboratory of the Cornell University. On examining the heavy brownish-black portion, which I presumed was the tin-stone, I was surprised to find only a faint indication of tin. Further investigation showed the mineral to be tantalite. On searching carefully all the fragments received, a considerable quantity of that mineral was found, and only a single streak of cassiterite, which was attached to a mass of spodumene. Another lot of specimens, from the same locality, consisted of

Jan 1, 1885

By E. Gybbon Spilsbury

Everybody who has had his attention turned to the gold-deposits of the Southern States, is acquainted with the undisputed fact of the existence, at least in the Carolinas and Georgia, of enormous areas of gold-bearing rocks. Long before the discovery of the precious metal in California, gold-mining on a very extensive scale mas a well-estab-

Jan 1, 1887

The practice of fine-grinding is now being so succeesfully carried on in some fields, notably in West Australia, and its advisability has been so frequently pointed out,l that the matter in this paper is not put forward as new; its chief object being to call attention to the importance of fine-grinding in the treatment of comparatively low-grade oree. I' have been engaged daring the last five years in the cyanide-treatment of ores in the Ohinemuri district (North Island), New Zealand, and I consider that, in the near future, extremely fine-grinding (almost sliming) will become a very im-

Jan 1, 1906

By A. C. Boyle

PaGE I. Introduction.........68 II. Location of the District,....... • 70 .. III. Stratigraphy...........73 Description of the Rocks.......73 Triassic Eruptives (Andesite Flows and Tuffs) ....73 Triassic Sediments (Shales and Slates)..75 Areal Geology ............75 Structure...-.......76 Folds............. 76 Faults..........79 Shear ...........80 Intrusives..........81 Alaskite Dike.........81 Andesitic Intrusion.......82 IV. PetrogRaphy of thE Rock Types......83 Andesite Flows.........84 Tuff 8...........84 Andesite Tuff........84 Rhyolite Tuff.....-.......85 Alaskite-Porphyry.......89 Andesite Dike........91 V. Description of the Mines......92 VI. Metalliferous Deposits ........ 95 Character of the Ores...........97 Mineralogy of the Ores.......97 Metallic Minerals.......97 Microscopic Character of the Ores...98 Secondary Enrichment....... 103 Genesis of the Ores ...........104 VII. The Sulphate Deposits.......109 Gypsum ..... HO Anhydrite......... ,... 110 Barite............ 110 Origin. with special reference to Gypsum....111 VIII. Summary.............. 113 IX. BIblYogRaphY.............114

Jan 1, 1915

By T. C. Sandford

Thermal conductivity measurements of intact rock specimens do not reflect the effects of natural rock discontinuities, and large scale insitu tests are location specific and costly. To allow extrapolation of laboratory measurements to rock masses with discontinuities, the effects of discontinuities on rock thermal conductivity were measured using divided-bar techniques. The introduced discontinuities lowered the thermal conductivity in all cases, and conductivity decreased systematically with increasing roughness of the discontinuity. Conductivity increased with increasing pressure on the discontinuity.

Jan 1, 1984

By G. R. St. Pierre, L. M. Adelsberg, R. Speiser

OXIDE platelets have been observed'-3 in oxidized tantalum adjacent to the metal-oxide interface, Fig. 1. The origin and identity of the platelets are important with respect to the proposal of an acceptable mechanism of tantalum oxidation. At reaction temperatures below 750°C, it has been established that the platelets

Jan 1, 1967

By T. F. Witherbee

THE Fletcherville Furnace was built in 1864 and 1865, making its first blast from August until October of the latter year, when it was blown out to prevent its "bunging-up." Repairs were made in time to enable it to be blown in again December 12th, 1865, the blast ending October 7th, 1866. Total product 1921.15 tons iron, an average of 6.8.2.5 tons per day, from ores yielding 44.8 per cent. Consumption of charcoal 223.2 bushels per ton of iron. The furnace journal up to this time shows no record of furnace dimen¬sions, or temperature of the blast, but as near as can be ascertained, they were as follows, viz. Height of stack, 42 feet. Diameter of bosh, 11 feet. Angle of bosh, 7 1/2 inches to 12 inches rise, about 58°. Diameter of open tunnel head, 42 inches. Number of tuyeres 3; each 3 inches in diameter. Dam 15 inches high. Tuyeres 24 inches high. Tymp 22 1/2 inches high. Diameter of steam cylinder, 20 1/4 inches. Stroke 5 feet. Diameter of blast cylinder, 64 inches. The engine is direct-acting horizontal non-condensing. December 26th, 1.866, the furnace was again put in blast, having been considerably altered in the crucible; the height of stack, bosh, and tunnel head remaining as before. Six tuyeres were put in, three in each of the side arches. The hearth or crucible was rectangular in form, 3 feet wide x 32 feet long x 62 feet high. Inclination of bosh 58°. Height of tuyeres 26 inches ; nozzles 2 1/4 inches diameter. Temperature of blast estimated to be about 500°.

Jan 1, 1874

By Alan E. Bland, Jerry G. Rose, Thomas L. Robl

This paper describes the observed variability of the chemical composition of coal preparation plant refuse for the major producing seams of Kentucky. Both the Appalachian Coal Field of eastern Kentucky and the Eastern Interior Coal Field of western Kentucky are represented. Also reported is the variability observed in the chemistry of the coal refuse due to cleaning, and the observed chemical variations between past and present production samples. This represents part of a larger study directed toward characterization and utilization of Kentucky coal refuse.

Jan 1, 1978

By D. M. S. Bhatia, Richard D. Hagni

Five sulfide minerals from the Magmont mine, southeast Missouri were sampled for 31 trace elements in over 300 samples by laser microprobe spectrographic analysis of polished sections. The concentration of several trace elements shows a pattern of progressive variation with depth (space) and variation with different paragenetic stages (time) of each mineral. Factor analysis of the geochemical data shows sympathetic correlation both in space and in time of Bi, Cd, Ge, and Sn in galena and sphalerite, and Ni and Co in sphalerite and marcasite.

Jan 1, 1981

By Cyril Smith

IN the study of the structure or the properties of a series of alloys or nonmetallic compounds, it is often advantageous to express the com-position not as percentage by weight, according to which the material is always made up and analyzed, but as the atomic percentage of the two constituents. The conversion from the one to the other is repre-sented by the formulas: 100A 100x Y x 100 ? x/A A [1] A+ B x + A/B(100-x) X _ 100yA 100y [2] yA+(100-y)B or y+A(100-y) where x and y are the weight and atomic percentages respectively of the element of atomic weight A, and (100 - x) and (100 - y) are the per-centages by weight and by atoms respectively of the element of atomic weight B. While calculations according to these formulas are simple, they are' time consuming if several conversions have to be made. In 1931 Water-man' constructed a nomograph for performing the conversion, but this did not permit an accuracy greater than about 1 per cent to be obtained in the neighborhood of 50 per cent. Olander2 has proposed a graphic method simpler than Waterman's and one that gives a uniform precision throughout the entire scale. The possible accuracy is about 0.5 per cent of the whole, depending on the size and accuracy of the coordinate paper used. Recently, Hermann3 has described a slide rule for making the calculations. These devices make use of the simple rearranged equation:

Jan 1, 1933

By Carlton D. Hulin

The usual concurrence in time and space of intrusive igneous activity, favorable structural disturbance and mineralization, which is so manifest in the mineralized district necessarily indicates a close interrelationship between these events. Evaluation of available evidence leads to the recognition that an appreciable time interval exists between the emplacement of the igneous intrusive and the formation of associated ore deposits. During this interval known portions of the intrusive are completely solidified, highly differentiated magma facies are injected as dikes, and important faulting occurs, which may fracture and shatter the solidified intrusive body. The highly differentiated dike types could only have originated in some deep portion of an underlying plutonic body that had reached an advanced stage of magmatic differentiation. Appearing after these dikes, the mineralizing solutions may likewise be presumed to have originated at great depth. Certainly no source for these solutions can be found in near-by portions of the intrusive igneous body. The association of igneous intrusives and clustering ore deposits must be recognized as resulting from structural control. The emplacemerit and the subsequent solidification and cooling of the intrusive set in operation forces that are responsible for the favorable structural disturbances that control the mineralized district. The emplacement of the body of fluid magma weakens the crustal rocks to the extent that failure due to strains originally present in the rock body may occur. Faulting of any type and of any magnitude may be the result. Subsequently, owing to the change of state from fluid magma to crystalline granitic rock, volume decreases approximating 10 Per cent may Occur, with resultant shrinkage and collapse within the rock body. Following solidification, thermal contraction, induced by cooling of the rock body, causes a further volume reduction of 6 per cent. This thermal contraction, extending over a lengthy period of time, results in a succession of minor fault movements. These small fault movements, occurring progressively throughout the period of mineralization, are responsible for maintaining the permeability of the rock body, without which access of the mineralizing solutions and the formation of the ore deposits of the mineralized district would be impossible. Introduction A proper understanding of the causes that have localized our mineralized districts should be of considerable value to geologist and engineer alike. under current conditions the known ore reserves of productive mining camps are being rapidly depleted. Although ore of the future will be derived in part from deposits now known and from Ore bodies that are still to be discovered within the limits of productive mining districts, in part at least it must come from mineralized districts whose existence or importance yet remain to be recognized. The mining geologist is thus faced with two problems of paramount importance: (I) the location of new ore bodies within known mineralized areas and (2) the location of new mineralized districts within whose confines, previously unknown, valuable Ore deposits may occur. Any contribution to our knowledge concerning the causes for the localization of mineralized districts

Jan 1, 1949

By Carlton D. Hulin

The usual concurrence in time and space of intrusive igneous activity, favorable structural disturbance and mineralization, which is so manifest in the mineralized district necessarily indicates a close interrelationship between these events. Evaluation of available evidence leads to the recognition that an appreciable time interval exists between the emplacement of the igneous intrusive and the formation of associated ore deposits. During this interval known portions of the intrusive are completely solidified, highly differentiated magma facies are injected as dikes, and important faulting occurs, which may fracture and shatter the solidified intrusive body. The highly differentiated dike types could only have originated in some deep portion of an underlying plutonic body that had reached an advanced stage of magmatic differentiation. Appearing after these dikes, the mineralizing solutions may likewise be presumed to have originated at great depth. Certainly no source for these solutions can be found in near-by portions of the intrusive igneous body. The association of igneous intrusives and clustering ore deposits must be recognized as resulting from structural control. The emplacemerit and the subsequent solidification and cooling of the intrusive set in operation forces that are responsible for the favorable structural disturbances that control the mineralized district. The emplacement of the body of fluid magma weakens the crustal rocks to the extent that failure due to strains originally present in the rock body may occur. Faulting of any type and of any magnitude may be the result. Subsequently, owing to the change of state from fluid magma to crystalline granitic rock, volume decreases approximating 10 Per cent may Occur, with resultant shrinkage and collapse within the rock body. Following solidification, thermal contraction, induced by cooling of the rock body, causes a further volume reduction of 6 per cent. This thermal contraction, extending over a lengthy period of time, results in a succession of minor fault movements. These small fault movements, occurring progressively throughout the period of mineralization, are responsible for maintaining the permeability of the rock body, without which access of the mineralizing solutions and the formation of the ore deposits of the mineralized district would be impossible. Introduction A proper understanding of the causes that have localized our mineralized districts should be of considerable value to geologist and engineer alike. under current conditions the known ore reserves of productive mining camps are being rapidly depleted. Although ore of the future will be derived in part from deposits now known and from Ore bodies that are still to be discovered within the limits of productive mining districts, in part at least it must come from mineralized districts whose existence or importance yet remain to be recognized. The mining geologist is thus faced with two problems of paramount importance: (I) the location of new ore bodies within known mineralized areas and (2) the location of new mineralized districts within whose confines, previously unknown, valuable Ore deposits may occur. Any contribution to our knowledge concerning the causes for the localization of mineralized districts

Jan 1, 1949

By H. R. Aldrich

This paper is not a treatise on the theory and practice of magnetic surveying. It presents a diagram upon which have been plotted observations taken with the simplest form of magnetic instrument, the lowly dip needle, over a large area astride the Lake Superior syncline of northern wisconsin. The exposures of the underlying formations are not sufficiently great in number nor fortunate in distribution to have provided the fuller understanding of the geology which has been secured by the use of the magnetic observations as an auxiliary tool or accessory in the hands of the geologist. The diagram (Fig. 2) in large part speaks for itself if studied in connection with the geological map (Fig. 1) for which it is the main control. It is presented to demonstrate the extent to which the use of such methods may aid in the solution of geological problems in a covered country. The diagram is probably unique in assembling the expression of such a wide range of formations, affected by so wide a range of secondary processes, and deformed by so many different structures in terms of magnetic variation. Few geologists outside of the Lake Superior country have had any first-hand experience in the taking of magnetic observations and the interpretation of the results in terms of geological conditions; nor have the Lake Superior men gone with the methods far afield from the mere tracing of iron formations. In more recent years the oil companies have gone heavily into investments in magnetometers, balances, and dip needles in the quest of concealed structural anomalies which are the favorable loci of petroleum accumulation. But these geophysicists come back from the fields with their collections of observations facing the question of interpreting the geological meaning of their magnetic anomalies. It is considered probable therefore, and certainly it is the hope of the writer, that the appended charts, or magnographs, which show how character of the country rock and its changes, structural strike and dip and their changes, depth of burial and its variation, contact metamorphic

Jan 1, 1929

By J. W. Whitlow, P. K. Theobald, W. C. Overstreet

Monazite placers in a region of the Carolinas ex- in 1951-1954 by the USGS are estimated to contain at least 53,000 short tons of thorium and 4600 short tons of uranium. None of these deposits is being mined. The 5200-sq mile area investigated extends northeast along the western Piedmont from the Savannah River in South Carolina to the Catawba River in North Carolina. Much of the region is 700 to 1100 ft above sea level. Gentle hills and broad interfluves give a local relief of 100 to 200 ft. This increases to 1700 ft at the west margin of the area where the east flank of the Blue Ridge is approached in South Carolina and the South Mts. are entered in North Carolina. This report is restricted to placers in the Piedmont. Monazite deposits in the Blue Ridge and coastal plain were not covered by the investigation. Monazite Mining in the Carolina Piedmont: Discovered in 1879 by W. E. Hidden,' the monazite placers in the Carolina Piedmont were first mined in 1886. The area was a major world source for thorium and the lanthanides until 1895, when Brazilian monazite entered the trade. Total output from the Carolina Piedmont has been nearly 5500 tons of monazite,2 but the placers have been idle since 1911, except for 48 tons produced between 1915 and 1917. Monazite mining was revived in the Carolinas in 1954 when a dredge operated by the Heavy Minerals CO. opened a fluviatile placer along Horse Creek in the coastal plain near Aiken, S. C. Geology and Mineralogy: Two recent papers",' have described the geology of the monazite placer district in the Piedmont between the Savannah and Catawba rivers; the general geology of the region has been reviewed by P. B. King.' These reports show that the placers are in locally derived alluvial sediments that cover the floors of shallow, narrow valleys in an area underlain by monazite-

Jan 1, 1960

By Richard Bosustow, Van Dyne Howbert

The Presidio mine of The American Metal Co. is situated in the "Big Bend" region, some 45 miles over state highway south of Marfa, a station on the Southern Pacific R.R. It lies 20 miles by road north of the Mexican border, in semidesert surroundings typical of this general section of the United States and the adjoining part of Mexico. All supplies are hauled in by truck from Marfa under contract. The concentrates and precipitates produced by the mill are carried by the same trucks to Marfa, from whence they are shipped, respectively, to the El Paso and Selby plants. History The mine was discovered about the year 1880 and was soon thereafter taken over for development by some army officers stationed at Fort Davis, Texas. It was later operated by the Presidio Mining Co., which treated the ore in a small pan-amalgamation mill from 1883 until 1913, when a cyanide plant was erected which has been in continuous operation ever since. When the present company, a subsidiary of The American Metal Co., Ltd., took over the mine in April, 1926, the ore-bearing zone had been worked for about 2200 ft. to the east of I the outcrops down the dip of the formation, at which point it is at a I vertical depth of 500 ft. below the surface. Up to that time the mine had produced some 1,150,000 tons of ore averaging about 17 oz. silver. After a development campaign the company started milling again in February, 1927. Since then the production has been approximately 4700 tons per month of ore; of which the yearly average grade has varied from 19.7 to 23.2 oz. silver, $0.20 to $0.50 gold, and 2.0 to 2.5 per cent. lead. No other property in this district has ever produced tonnage of any importance.

Jan 1, 1931

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Jan 1, 1946

[Trans. No. Place Date Vol. Page 1. Wilkes-Barre, Pa.* May, '71.. 1 3 2. Bethlehem. Pa Aug., '71.. 1 10 8. Troy, N. Y Nov., '71.. 1 1S 4. Philadelphia, PaFeb., '72.. 117 5. New York, N. Y.*May: '78.. 120 5. Pittsburgh, PaOct., '72.. 125 7. Boston, MassFeb., '78.. 128 8. Philadelphia, Pa.* May, '78.. 2 3 9. Easton, POct., '78.. 27 10. New York. N. YFeb.. '74.. 2 11]

Jan 1, 1946

[Trans. No. Place Date Vol. Page 1. Wilkes-Barre, Pa.*...May, '71.. 1 3 2. Bethlehem, Pa Aug., '71.. 1 10 3. Troy, N. Y Nov., '71, , 1 13 4. Phildelphia, Pa Feb., '72.. 1 17 5. New York, N. Y. May, '72 120 6. Pittsburgh, Pa Oct., 7. Boston, Mass Feb., '73.. 1 28 8. Philadelphia, Pa.* ... May, '73.. 2 3 9. Easton, Pa Oct., '73.. 2 7 10. New York, N. Y Feb., '74.. 2 11 11. St. Louis, Mo.* May, '74.. 3 3 12. Hazleton, Pa Oct., '74.. 3 8 13. New Haven, Conn.... Feb., '75.. 3 15]

Jan 1, 1940

By M. R. TECK, N. Rudd, L. K. Thomas, D. L. Katz

The authors are to be congratulated for presenting the first comprehensive paper on the theory and practice of threshold pressure determination in connection with underground gas storage. It is of particular value since most previous experimental work on this subject has been proprietary to the commercial laboratories engaged in such testing and to their clients. This dlscussion is presented in amplification of the subject paper, not in criticism, and is based upon our experience with approximately 5,000 threshold pressure determinations. Our comments are directed primarily to the experimental procedures as described by Thomas et al. It should be noted that, while clay mineral-rich lithologies are the most common caprock materials, the samples used (Table 1) include low permeability sandstones and carbonates, but do not include shales or other formations in which clav minerals exert a dominant effect. While our experience on samples analogous to those investigated by the authors generally confirms their findings, we have found that even more rigorous experimental conditions must be imposed where clay minerals are the controlling factor. These additional conditions result from the well-known molecular character of the clay minerals themselves in which water is interlaminated with, and bonded to, silicate sheets, thus becoming an essential component of the molecule. In many clay minerals the character of the intersheet bonding, and thus the dimension of the lattice, is strongly affected by variations in the identity and concentration of cations present in the intersilicate water. On a supermolecular scale, adsorbed water films on particle or "flakes" of shale provide much of the cohesive force necessary to maintain mechanical strength. The thickness of these films is variable and inversely proportional to intergranular pressure within the dimensional limits involved in caprock investigation. The thickness of the intersilicate water layers may also be subject to pressure under some conditions. These considerations are reflected in several necessary modifications of the experimental procedures described by the authors. Two of these are, in our judgment and experience, of such importance that they cast real doubt on the validity of data obtained on argillaceous materials without their application. The very careful resaturation procedures proposed by the authors should give good results in connection with the relatively "inert" lithologies used in their experiments. Our experience suggests, however, that they would create more problems than they would eliminate if applied to argillaceous materials. 1. Drying of the sample at the temperature and for the duration indicated by the authors not only will dessicate the sample with consequent shrinkage cracking, parting along bedding planes, and even total disassociation in the case of fissile shales, but it may also alter the character of the clay minerals themselves — in some cases irreversibly. 2. Prolonged evacuation to 2 microns Hg further dessicates the sample and is even more effective in reducing the intersilicate water content. 3. Resaturation with water differing in pH or chemical content from that existing originally in the sample also serves to alter the nature of the sample, particularly its structure and strength. 4. Our experience has been that, even with the thorough precautions proposed by the authors, complete resaturation of very fine grained materials is rarely obtained. Yet our experience confirms the

Jan 1, 1969

By E. W. Edson, F. W. Hertal

In some fields the problem of mud fluid is simple and easy of solution. But in the Ventura Avenue field the acquisition and disposal of good drilling mud is not the least of the problems that confront the operator. In fact, mud fluid in the Ventura Avenue field is a very important factor in the drilling of the wells. It is quite probable that many of the factors affecting mud in this field will not be found in most of the fields with which the reader is familiar. However, in the fields where the mud fluid causes no apparent problem it is probable that some of the points brought out in this paper could be used to economic advantage. In fields where caving and squeezing formations and high gas pressures are present, as in the Ventura Avenue field, it is believed that application of methods outlined will be of great assistance in drilling wells. On account of the sandy nature of the formation and the lack of suitable shale bodies in the strata drilled through in the Ventura Avenue field, the wells make practically no mud during drilling. It is necessary therefore to supply drilling mud to the wells that will carry the drill cuttings to the surface, and also will " wall up" the drill hole and prevent the sandy formations from caving. Mixing and Handling Mud Fluid The clay used to make the mud fluid is obtained from a shale stratum in the upper Pico (Plioccne) formation found about a mile on either side of the field. Since high gas pressures and caving formations were first encountered in the Ventura Avenue field and mud fluid was needed to combat them, the mixing of this mud fluid has gone through a process of evolution. First, the clay was mined and hauled to the derrick, where it was shoveled into the well and left for the churning action of the bit to mix into a mud in the hole. The next move was the construction of a mixer to mix the clay to a mud fluid which was pumped into the well. These mixing

Jan 1, 1930