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By J. J. Bodmer

Although the similarity between puzzolana, or trass, and blastfurnace slag, as seen by comparison of the analyses, is a well-known fact, blast-furnace slag has not been used commercially as a substitute for those cementing materials. The reason, the writer apprehends, lies in the fact that unless such slag is disintegrated or subdivided by rolls, the process must either be too costly, or the material is not in a fit and proper condition for the purpose. In order to produce a reliable slag cement, the slag must be ground together with the lime into an impalpable powder. The subdivided slag must, therefore, be perfectly dry, and, at the same time, friable. The stronger the hydraulic properties of the lime, the more reliable the slag cement will be, and practice has proved, that the slag from a gray-iron furnace gives the best results. The slag cement which has given the results shown in the annexed table, under pressure tests, was composed of six parts of slag, from a blast-furnace producing No. 3 foundry iron, and one part of lime, of medium hydraulic properties. The above-described class of cement bears storing as long as most Portland cements, and the cheapness of its production is self-evident.

Meeting of June 4, 1915.-The President announced the appointment of the following Committee on National Reserve Corps of Engineers: Dr. Henry S. Drinker, Chairman; Arthur S. Dwight, and Warren A. Wilbur; also, the appointment of Arthur F. L. Bell as Chairman of the Committee on Petroleum and Gas, and of James F. hemp as Chairman of the Committee on Mining Geology. All of these appointments were approved. It was voted that the following minute be, placed on record and a copy sent, by order of the Board of Directors, to the family of John Birkinbine: "The Board of Directors of the American Institute of Mining Engineers hereby records its sense of sorrow and loss in the death of John Birkinbine, a former President, and for many years an active member of the Institute, and contributor to its Transactions. "Mr. Birkinbine's eminence as an engineer, author and editor, intimately connected with the industrial progress of the United States, brought him into contact With the leaders of science and the captains of industry, among whom his genial and estimable personal character won for him many friends; and his departure in the prime of Strength and usefulness is mourned by a wide circle."

Jan 7, 1915

By F. W. DeVries

The subject article is an excellent comparison between two potential oxidants, molecular oxygen and hydrogen peroxide, as used in the Palangana field at the time of the trials. The tests showed no advantage to using hydrogen peroxide; however, it would be unwise to generalize that the experience in these trials was universally true. During the time of the work cited, extremely high levels of an unusual impurity were recycling in the lixiviant, which substance was a catastrophically destructive catalyst for peroxide. Since this material was not removed before recycle, it was not surprising that much of the peroxide fed was decomposing in the feed piping and never made contact with the uranium mineralization. Under these conditions, indeed, peroxide showed no improvement over oxygen. This is, however, perhaps the most adverse environment encountered to date in US in-situ uranium leaching. In other operations, peroxide has proved advantageous where two factors have been exploited: 1.Despite the tendency for Hz02 to decompose to water and oxygen in the in-situ leach environment, its higher redox potential before decomposition has provided higher leach rates. In some formulations, overloading beyond the O2 saturation equivalent with peroxide has allowed higher oxidant levels, and higher leaching rates, when overloading with molecular O2, led to vapor-locking.

Jan 1, 1983

By AIME

PERHAPS, back in the early eighties, the fates were advised that the world had need of a determined man, yet one who could always inspire teamwork; at any rate on Dec. 20, 1881, Louis Shattuck Cates was born to Edwin Wallace and Emily Allen (Johnson) Cates, in Boston. To his friends he has always seemed a little more determined than anyone else they knew-yet his capacity for organization and enlisting friendly co-operation from all with whom he became associated has perhaps been his greatest asset. His will and imagination set the goal, but his friendliness and qualities of leadership brought results. He was born just nine years after the great Morenci mine was opened by Robert Metcalf and his associates. Educated in the public schools of Boston, Mr. Cates was graduated from Boston High School, and since at that time Boston was headquarters for many of the great mining enterprises and promotions in the country, he chose Massachusetts Institute of Technology as the college which would best prepare him to succeed in the mining industry. He was granted a Degree of S.B. from "Tech" in 1902, but already his getting-along-with-people talent had won him honors. He was class president in his junior year, and "First Marshal" at graduation.

Jan 1, 1946

By L. M. Johnson, C. G. Janes

INTRODUCTION In May, 1966, the General Services Administration (GSA) announced a program to encourage additional domestic production of copper in the interest of national security. Upon learning of the copper production expansion program, Duval Corporation entered into negotiations with GSA for development of the Sierrita copper-molybdenum property under the program. Agreements between the GSA and Duval Sierrita Corporation, a wholly owned subsidiary of Duval Corporation, were concluded in 1967, with the Sierrita Concentrator beginning operation in 1970 at a designed capacity of 72,000 STPD. Subsequent additions and modifications have expanded capacity to 90,000 STPD. This property, located approximately 20 miles south of Tucson, Arizona, represents an investment including working capital of about $200 million. These funds were provided from an $83 million loan from GSA, repayable in copper valued at 38 cents per pound, $48.75 million of bank loans subject to U. S. Government V-loan guarantees, and Company capital contributions. Current general operating statistics for the concentrator are listed below: [Ore Grade 0.32% Cu., 0.030"/. Mo. Daily Tons Milled 90,000 STPD Annual Copper Product ion 94,600 Tons Annual Molybdenum Production 15,000,000 Lbs. Annual Silver Production 1,135,000 Ounces]

Jan 1, 1976

By Ben. B. Cox

The principal events during the year consisted in the exploitation of the Kirkuk field, the regular operation of the four-million-ton pipe line to the Mediterranean, and the discovery of low-gravity oil on three other structures in the West Tigris (Shergat) area. The Iraq Petroleum Co., Ltd. continued the systematic exploitation and exploration of its Kirkuk field, maintaining a carefully unitized operation. Bottom-hole pressure differentials and low gas-oil ratios were maintained. All crude was produced by flowing The cleaning up following the construction of the Mediterranean pipe line, which began deliveries in August, 1934, was completed during the first quarter of 1935. The line easily maintained its rated capacity for the remainder of the year. The Mosul Oilfields, Ltd., through its operating subsidiary, the B.O.D., Ltd., expanded its exploratory organization from 9 to 16 drilling rigs and discovercd 20" A.P.I. crude on the Sadid, Hibbarah and Qasab anticlines. Whether these discoveries will be commercial pools remains to be proved. The Qaiyarah-Najmah-Jawan field, which was discovered by the I.P.C. in 1928, was extended arid production was found in the Eo-Cretaceous as well as the "Main Limestone" (Eocene, Oligocene and Lower Miocene). Gas caps were found under each of the crests of the West Tigris structures. Negotiations are in progress between the Mosul Oilfields, Ltd. and the Iraq Government for the extension of the Anatolian Railway from the Turkish border to Mosul, with a view to tanking the heavy West Tigris crude to the Mediterranean. The subsidiary of the Anglo-Iranian Oil Co., Ltd.', the Khanaqin Oil Co., Ltd., continued to operate its Naft Khaneh field near the Iranian (Persian) border to supply the local Iraq market through the Rafidain Oil Co., Ltd. Somewhat more than 28 million barrels of crude was produced in Iraq during 1935. Crude delivcred to the pipe line for export during the years 1934 and 1935 was: Year BaRrels 1934................................................. 7,096,669 1935................................................. 27,014,904 Total as at Dec. 31, 193.5.............................. 34,111,573 ° Converted at an avcrage of 7.0 bbl. per ton.

Jan 1, 1936

The principal events during the year consisted in the exploitation of the Kirkuk field, the regular operation of the four-million-ton pipe line to the Mediterranean, and the discovery of low-gravity oil on three other structures in the West Tigris (Shergat) area. The Iraq Petroleum Co., Ltd. continued the systematic exploitation and exploration of its Kirkuk field, maintaining a carefully unitized operation. Bottom-hole pressure differentials and low gas-oil ratios were maintained. All crude was produced by flowing The cleaning up following the construction of the Mediterranean pipe line, which began deliveries in August, 1934, was completed during the first quarter of 1935. The line easily maintained its rated capacity for the remainder of the year. The Mosul Oilfields, Ltd., through its operating subsidiary, the B.O.D., Ltd., expanded its exploratory organization from 9 to 16 drilling rigs and discovercd 20" A.P.I. crude on the Sadid, Hibbarah and Qasab anticlines. Whether these discoveries will be commercial pools remains to be proved. The Qaiyarah-Najmah-Jawan field, which was discovered by the I.P.C. in 1928, was extended arid production was found in the Eo-Cretaceous as well as the "Main Limestone" (Eocene, Oligocene and Lower Miocene). Gas caps were found under each of the crests of the West Tigris structures. Negotiations are in progress between the Mosul Oilfields, Ltd. and the Iraq Government for the extension of the Anatolian Railway from the Turkish border to Mosul, with a view to tanking the heavy West Tigris crude to the Mediterranean. The subsidiary of the Anglo-Iranian Oil Co., Ltd.', the Khanaqin Oil Co., Ltd., continued to operate its Naft Khaneh field near the Iranian (Persian) border to supply the local Iraq market through the Rafidain Oil Co., Ltd. Somewhat more than 28 million barrels of crude was produced in Iraq during 1935. Crude delivcred to the pipe line for export during the years 1934 and 1935 was: Year BaRrels 1934................................................. 7,096,669 1935................................................. 27,014,904 Total as at Dec. 31, 193.5.............................. 34,111,573 ° Converted at an avcrage of 7.0 bbl. per ton.

Jan 1, 1936

The pattern of the coal industry west of the Mississippi River, so far as its history is concerned, is entirely different from that to the east of the "Father of Waters." When the Louisiana Purchase was consummated, one of Jefferson's first thoughts was to ascertain what sort of a country had been purchased, and to that end he sent Lewis and Clark to ascend the Missouri River and to reach the Pacific Ocean if possible, but above all to bring back a report showing the character of the country, its mineral and other resources, inhabitants, etc. This first expedition was supplemented by others to various parts of the vast domain for the same purpose; years later, when transportation routes were necessary to hold and develop the western country, a number of expeditions were sent to explore possible routes for railroads. The records of nearly all of these explorers, as will be shown later, contain references to coal in many localities, the possible value of which was realized but its potential value remained dormant for many years until increasing population and methods of transport made markets available. Missouri was the first state west of the Mississippi in which coal was produced and the names of a number of places show that the French were familiar with the coal deposits there. Lewis and Clark, soon after they left St. Louis, passed "a remarkable Coal Hill on the Larboard Side, called by the French Carbonere, this hill appeares to Contain great quantity of Coal."1 This hill was about seven miles below St. Charles. No other outcrops were seen by them until they had passed the present limits of the state. The Louisiana Gazette of April 9, 1805 contained an article on "The Missouri," author not stated, which said, "the short stay we have generally made among the savage nations has prevented us from making those researches, which would have supplied us with a more extensive information respecting the various mines found on the borders of the Missouri; we know with certainty only those of iron, lead and coal." In 1806 Pike passed through Missouri on his tour to Mexico. On August 17th, along the Osage River he remarked, "here the river-bank is

Jan 1, 1942

By L. C. Glenn

The account of oil and gas production in Tennessee, and of the geological factors related to such production, as given by the writer' a few years ago needs to be supplemented by brief statements as to production and development to bring it up to date. Activity in searching for favorable geological structures or in drilling given areas has never been comparable to the intensive work done in states of large production. It is not possible, therefore, to prepare a statement giving the details that may be readily available in such states, but instead one must be content with more general statements. In the past 10 or 12 years there has been a moderate amount of drilling for both oil and gas widely scattered over the state. Of much of this there is no available record. Morgan, Clay, Scott and Pickett counties have had more oil-drilling activity than any other counties, and likewise they have had almost all of the oil production. In Scott and Morgan counties production centers about Sunbright and Glenmary, the oil coming from the St. Louis limestone at a depth of 1200 to 1500 ft. Wells usually are small but generally hold up well. In Clay, Pickett, Fentress, Overton, Macon and Sumner counties there is a large area in which there are many small structural domes, some of which have been drilled. Wells vary from a few barrels to several hundred flush production and last for some years. The oil comes from porous weathered zones, mostly in the Trenton division of the Ordovician, though some comes from lower horizons beneath one or more bentonite beds that serve as horizon markers and are known as the "pencil cave." Wells recently drilled in the Central Basin and in the Western Highland Rim have been dry or have had only shows of oil. The horizons tested are also usually Ordovician in the Central Basin and usually either Ordovician or Mississippian; occasionally also Devonian on the Highland Rim. In the Gulf Embayment area of West Tennessee there has been but little activity. A well near Ridgely said to be over 2200 ft. deep is supposed to have entered Upper Cretaceous sands and clays in the lower

Jan 1, 1934

By S. J. Sindeband

J. WULFF*—It seems to me that the author could improve the quality of his high temperature material by using less nickel as a cementing agent in hot pressing. Furthermore, to avoid the presence of undilfused nickel which would not be oxidation resistant, permit me to suggest that he use a nickel-chromium powder containing a small percentage of boron. This would give him a liquid phase at a lower temperature and accelerate both sintering and homogenization. The commercial alloy known ascolrnonoy contains sufficient chromium to be heat resistant and sufficient boron to be of low melting point. Such an alloy may be applicable as a cementing agent in increasing the quality of Mr. Sindeband's alloys. Finally 1 believe the author unfair to himself in expecting a porous material to have properties equivalent to one of 100 pet density. S. J. SINDEBAND—Dr. Wulff's point is well taken. Early in the program we realized the fact that we were having difficulty with these low-melting alloys, and we had hoped, since the colmonoy alloys of which you speak are at the nickel-rich end of the diagram, that by going to the other end of the diagram (chromium boride-rich) we would not have this difficulty. Thus we tried to use very small percentages of binder; but for reasons which are not exactly apparent we found that when we did this it was necessary to raise the pressing temperature to a point which we were unable to attain. For all compositions which we tried using nickel, or for that matter any nickel iron or cobalt containing material as a binder, we found that we would get low melting boride phases, which as you point out are the commercial "strength" of the hard-facing materials. 1 personally believe these owe a great deal of their behavior and even hardness to the nickel boride which is considerable evidence when an alloy of chromium boride is made with nickel. Nickel boride itself is very hard. We did try pure chromium as a binder and found there was considerable difficulty in handling it, particularly since we could not just hot press under

Jan 1, 1950

By Gilbert Cady

EXTENSIVE Sampling of coal in Illinois during the past 10 or 12 years by the State Geological Survey, in cooperation with various organizations, such as the U. S. Bureau of Mines, the University of Illinois, and the Illinois Cooperative Mining Investigations, has made possible the delineation of two areas of low-sulfur coal in the southern part of Illinois. The sulfur content is less than 1.25 per cent., so that, if otherwise suitable, these coals can be employed for metallurgical uses and for the manufacture of water-gas and retort gas. One of these areas is small and lies in Jack-son County, near Murphysboro, the other is much larger and includes a large part of the famous Franklin County field. A small area of No. 2, or Murphysboro, coal has been worked for many years near the town of Murphysboro, Jackson County, Ill. In two mines, at least, the coal has a sulfur content of less than 1.25 per cent. It is doubtful, however, whether this field will ever be a source of large tonnage as the total area underlain by low-sulfur coal in workable thickness is probably less than 15 sq. mi. (24.14 sq. km.), and a large part of it has already been worked out. The location of the area of low-sulfur coal in the Franklin County field is shown in the accompanying map. The small area underlain by the Murphysboro low-sulfur coal is shown near the town of that name in the central part of Jackson County. The larger area lies in the west side of Franklin County, extending also about 6 mi. (9.65 km.) south into Williamson County, about 4 mi. (6.43 km.) west into northern Jackson and western Perry County, and northward an undetermined distance into Jefferson County. All but the northern limit of the area is fairly well defined by sampling in numerous mines. The inner cross-lined area is underlain by coal having less than 1 per cent. sulfur, the outer boundary surrounding the area Underlain by coal having less than 1.25 per cent, sulfur.

Jan 7, 1919

By J. F. Myers, F. M. Lewis

The purpose of the mill tests reported herein, was to determine the relative power efficiency of fast and slow rod mill speeds on the ores of the Tennessee Copper Co. The tests were carried out at the Isabella Mill of the Tennessee Copper Co. under normal operating conditions. Every effort was made to keep the ore supply and other conditions constant, but it will be noted that some slight variation did occur. The open circuit 6 by 9 rod mill, and ore, used in these tests have been previously described.' Four motor drive pinions were available and the tests were performed in the following manner: each pinion was used to drive the mill for a period of one week. Constant sampling prevailed during the test run, and a composite sample for each speed test was made. Realizing that some slight liner wear took place during the four-week test-run, and that some slight variation of the ore may have taken place, a second and then a third series of four-week test-runs were made with the four different pinions. The screen analysis of each of the three-week run samples at the various speeds were composited and the results are shown in Table 2. The authors feel that the 22 weeks of operation consumed during these test-runs would represent fairly the effect of each mil1 speed. The data of line 37 show that within the error of sampling and plant operation, the tons of minus 65-mesh material generated per horsepower hour was the same at all four speeds. Obviously, rod and liner consumption could not be determined for each mill speed in so short a time. The rod load was maintained at a uniform level throughout the series of tests. The authors have operated rod mills at various speeds over the past several years, and it is their observation that rod consumption is directly proportional to the mill speed. Likewise, that the rod consumption per unit of work performed is a constant, providing that all other operating factors remain the same. It is a well known fact that the efficiency increases in a ball mill as the speed decreases. This is due to lateral segregation of the large and

Jan 1, 1950

By Walter F. Pond, Kendall E. Born

Production of crude oil in Tennessee during 1935 approximated 20,000 bbl., an increase of about 5000 bbl. over 1934. The total production for the state is an estimate, since the only definite figures available are those for Scott and Morgan counties, where 12,377 bbl. were marketed during 1935, an increase of 4305 bbl. over the preceding year. The oil fields of Scott and Morgan counties are near the eastern margin of the Cumberland Plateau where Pennsylvanian sediments rest uncon-formably upon the Mississippian. Near Glenmary, in Scott County, the production is from the middle Mississippian, probably near the top of the St. Louis limestone. Accumulation is due to a low, east-west anticline which has been cut by a fault. This field is now 20 years old and only a few wells are pumped at present. Oil was Struck along Boone Camp Creek in Morgan County in 1924 and there has been small production since that time. The oil comes from the middle of the Fort Payne formation of lower Mississippian age at a depth of 1400 ft. Geologic work in the area has shown that a terrace and porosity conditions in the Fort Payne formation account for the accumulation. The production figures on a number of small producing wells in Clay and Overton counties are not available. As pointed out by Glenn1, the installation of small local skimming or topping plants in the fields has curtailed the shipment of crude oil out of the state and as a result it has been impossible to secure accurate production figures in these counties. The operators, in most cases, are reluctant to give information, and there is no state law requiring them to do so. Based upon information available to the writers, it is believed that between 7000 and 8000 bbl. is a fair estimate of the production in Clay and Overton counties during 1935. More than 500 wells have been drilled in Clay County, the majority of which were drilled east of Cumberland River. Some eight small oil fields have been developed in the county within the past 12 years, a

Jan 1, 1936

By R. Philip Hammond

MONAZITE has had a Cinderella-like history. Although nearly go per cent pure rare-earth compound (rare-earth phosphate) it was sought at first not for the rare earths but for the sake of a minor constituent-thorium. The thorium, essential for the Welsbach gaslight mantle, was present in only small quantities and the principal constituents, the rare earths, were largely discarded. Gradually, however, the rare earths have developed uses of their own and today have left the thorium far behind in value. OCCURRENCE Monazite was first produced commercially about 1886, in North Carolina, where it was collected in small sluices by farmers who found it in stream beds on their land. The deposits were later exploited on a larger scale, but were mostly abandoned in a few years, when monazite from Brazil came upon the market in far larger quantities. Domestic production ceased entirely in 1906. The Brazilian source is still active, together with Indian, Dutch East Indies, and Australian deposits. Several other localities in the United States have yielded monazite, but none of these has produced commercially as yet. Monazite occurs originally in pegmatites and gneisses, through which, unfortunately, it is scattered in highly dispersed form. All commercially useful deposits consist of transported monazite sands liberated by erosion and concentrated by the action of water, which has sluiced away lighter materials and concentrated the heavy (D = 5.0 to 5.2) grains of monazite, together with ilmenite, zircon, garnet, and other dense minerals. The Carolina deposits were in stream beds; most of the other deposits mentioned are on or near the seashore, where the action of the waves has served to concentrate the monazite. In most cases today, the sands are worked to obtain the ilmenite and zircon, as well as monazite. The minerals are separated by means of sluices, dry tables, and magnetic separators, and each is finally obtained nearly pure. No crushing or grinding is necessary. The concentrates are shipped in fiber bags. COMPOSITION OF MONAZITE As Table I illustrates, monazite is the anhydrous orthophosphate of the cerium [ ] group of rare-earth elements. A small amount of yttrium and terbium group phosphate is also present.* All the rare-

Jan 1, 1946

The opening session of the Institute was held at Hazle Hall, Tuesday evening, October 27th, with a large attendance of members. President Raymond called the Institute to order, and after a few introductory remarks, introduced Mr. I. Lowthian Bell, President of the Iron and Steel Institute of Great Britain, and Honorary Member of the American Institute of Mining Engineers. Mr. Bell was received with great applause, and made his acknowledgments in a brief speech, of which the following is the substance: He desired to thank the Institute personally for the honor conferred upon him in his election to membership, and also for the invitation extended last year to the body of which he was President. The difficulty felt by many members of the Iron and Steel Institute, of leaving for a long journey the works of which they had charge, aggravated by special industrial troubles at the time of the invitation, had obliged them to conclude that it could not then be accepted in a fitting manner. The iron .manufacture of this country is a subject of great interest to Englishmen, who look with pride upon the achievements on this side the water of the descendants of a common ancestry. His own reception in this country had far surpassed in cordiality even the well-grounded anticipations he had formed from the assurances of the President and other friends. Notwithstanding the flattering manner in which his friend, in introducing him to the Institute, had spoken of his contributions to the science of iron metallurgy, he could not take to himself alone the significance of this welcome. He knew it was a recognition of the services rendered by the body which he had the honor to represent; and he was glad to see present a member of that body, Mr. Thomas Whitwell, who had fortunately been able to make the journey at this time, arid whom he had had the pleasure of meeting on the shores of Lake Champlain. He had been requested to say something of his impressions of the American iron industry. It was not easy to digest so soon the vast

By Kendall E. Born, Walter F. Pond

Production of crude oil in Tennessee during 1935 approximated 20,000 bbl., an increase of about 5000 bbl. over 1934. The total production for the state is an estimate, since the only definite figures available are those for Scott and Morgan counties, where 12,377 bbl. were marketed during 1935, an increase of 4305 bbl. over the preceding year. The oil fields of Scott and Morgan counties are near the eastern margin of the Cumberland Plateau where Pennsylvanian sediments rest uncon-formably upon the Mississippian. Near Glenmary, in Scott County, the production is from the middle Mississippian, probably near the top of the St. Louis limestone. Accumulation is due to a low, east-west anticline which has been cut by a fault. This field is now 20 years old and only a few wells are pumped at present. Oil was Struck along Boone Camp Creek in Morgan County in 1924 and there has been small production since that time. The oil comes from the middle of the Fort Payne formation of lower Mississippian age at a depth of 1400 ft. Geologic work in the area has shown that a terrace and porosity conditions in the Fort Payne formation account for the accumulation. The production figures on a number of small producing wells in Clay and Overton counties are not available. As pointed out by Glenn1, the installation of small local skimming or topping plants in the fields has curtailed the shipment of crude oil out of the state and as a result it has been impossible to secure accurate production figures in these counties. The operators, in most cases, are reluctant to give information, and there is no state law requiring them to do so. Based upon information available to the writers, it is believed that between 7000 and 8000 bbl. is a fair estimate of the production in Clay and Overton counties during 1935. More than 500 wells have been drilled in Clay County, the majority of which were drilled east of Cumberland River. Some eight small oil fields have been developed in the county within the past 12 years, a

Jan 1, 1936

By Tracy Jarrett

IN making gold alloys possessing certain physical properties, such important factors as corrosion resistance, color, hardness and melting points must be considered. All of these requirements depend directly upon the composition. It is possible to obtain the same colored gold alloy by using different compositions, but in doing so one may bring in some undesirable property. Other investigations have been carried on in this field by F. E. Carter,1 E. M. Wise,2 and L. Sterner-Rainer.3 To make a complete study of the effect of composition upon these properties, a systematic investigation was carried on involving a range of copper content from 85 to 65 per cent. Elements such as zinc, silver and nickel were used to replace in part the copper content. The gold content in all the alloys remained constant. Only 10-karat gold alloys of those containing 41.6 per cent gold will be considered. All of the alloys were made in an induction furnace. Each alloy was cast in a 3 by ¼ by ¾ -in. ingot. The method of obtaining the melting points and making color determinations was described in a previous paper.4 The Rockwell B scale with the ball and 100-kg. weight was used for all hardness determinations. The submersion of test pieces in concentrated nitric acid is one of the standard corrosion tests used in the optical trade. A test piece in the 50 per cent cold-worked condition, ½ by 2 by 0.043 in., is blanked from a strip using a. die, and the weight, loss per square inch of surface is taken as a means of comparison. The time for this test is 2 ½ hr. of actual sub-mersion of the test piece in the acid. This standard test was applied to all of the 10-karat gold alloys discussed in this paper. The tensile tests were made upon strips of the dimensions shown in Fig. 1. The test pieces after blanking were annealed at 1300° F. for 20 min. and cooled in air. The "drop of the beam" method was used in determining the yield point, as there was a very marked "drop" when the yield point was reached.

Jan 1, 1939

By Y. P. Chugh, R. A. Missavage

Moisture has been known to influence strata failures in coal mines for a long the. A concise review of what is known about effects of moisture on strata control with emphasis on the Illinois basin coal mines is presented in this paper. Some approaches to mitigate the effects of moisture-leaving coal in the roof, guniting, shotcreting, application of sealants-are then briefly discussed.

Jan 1, 1982

By R. Gibson, F. S. Turneaure

The tin deposit of Monserrat, Bolivia, consists of one major vein 1600 m in length. The ore is unusual because of the notable quantity of teallite, even though cassiterite is the principal tin mineral. The deposit, formed at shallow depth under a wide range in temperature, may be classed as xenothermal. Polished sections reveal a complex history of replacement, with low-temperature minerals deposited before high-temperature minerals. THE Monserrat mine1'2 of the Compania Minera Monserrat is located 11 km east of Callipampa, a station on the Antofagasta and Bolivia Railway some 55 km south of Oruro. The mine lies in a group of low hills on the east slope of a broad valley of northerly trend. The valley is separated from the altiplano to the west by a prominent ridge that rises several hundred meters above the surrounding country (fig. 1). Callipampa is situated a short distance west of the ridge, near the east margin of the altiplano. The elevation at Callipampa is 3700 m and at the mine 4100 m. Monserrat is near the northeast limit of what may be called the Poopo-Pazna district, an area of northwesterly trend about 25 km in length and 15 km in width. The district includes the tin-silver prospects of Poopo to the north, the zinc-tin deposits of Salvador to the southwest, and the tin-tourmaline veins of Avicaya to the south. Along the prominent ridge already mentioned, which forms the western limit of the district, there are several tin and antimony prospects including the Trinacria mine, which is famous for its fine specimens of cylindrite. Although the principal ore mineral is cassiterite, the tin deposit of Monserrat contains an unusual amount of teallite. Cassiterite occurs in part as a finely granular mixture with sulphides of iron and zinc and in part as needle tin of late hypogene age. The regional structure is dominated by broad folds typical of the Andes of Central Bolivia and similar to those of the Llallagua district. The area adjacent to the Monserrat mine is underlain by thin-bedded shale somewhat variable in color but predominantly dark grey to black. The beds strike northwest and dip at low angles southwest, forming part of the northeast limb of a major syncline. A resistant sandstone formation, which underlies the black shale, crops out along a ridge east of the mine and also accounts for the high ridge to the west that was previously mentioned. No igneous rock of any kind is found at Monserrat. The nearest intrusive bodies known are the irregular dikes and masses of quartz porphyry at Avicaya about 10 km to the south. Mine Workings The Monserrat property includes one main vein, which can be followed on the surface for 1600 m, and two or three branch veins of distinctly minor importance. The principal haulage tunnel, referred to as the San Carlos adit or level III, extends northeasterly for 1700 m, following the main vein throughout most of this distance. Above the adit, there are

Jan 1, 1951

By F. S. Turneaure, R. Gibson

The tin deposit of Monserrat, Bolivia, consists of one major vein 1600 m in length. The ore is unusual because of the notable quantity of teallite, even though cassiterite is the principal tin mineral. The deposit, formed at shallow depth under a wide range in temperature, may be classed as xenothermal. Polished sections reveal a complex history of replacement, with low-temperature minerals deposited before high-temperature minerals. THE Monserrat mine1'2 of the Compania Minera Monserrat is located 11 km east of Callipampa, a station on the Antofagasta and Bolivia Railway some 55 km south of Oruro. The mine lies in a group of low hills on the east slope of a broad valley of northerly trend. The valley is separated from the altiplano to the west by a prominent ridge that rises several hundred meters above the surrounding country (fig. 1). Callipampa is situated a short distance west of the ridge, near the east margin of the altiplano. The elevation at Callipampa is 3700 m and at the mine 4100 m. Monserrat is near the northeast limit of what may be called the Poopo-Pazna district, an area of northwesterly trend about 25 km in length and 15 km in width. The district includes the tin-silver prospects of Poopo to the north, the zinc-tin deposits of Salvador to the southwest, and the tin-tourmaline veins of Avicaya to the south. Along the prominent ridge already mentioned, which forms the western limit of the district, there are several tin and antimony prospects including the Trinacria mine, which is famous for its fine specimens of cylindrite. Although the principal ore mineral is cassiterite, the tin deposit of Monserrat contains an unusual amount of teallite. Cassiterite occurs in part as a finely granular mixture with sulphides of iron and zinc and in part as needle tin of late hypogene age. The regional structure is dominated by broad folds typical of the Andes of Central Bolivia and similar to those of the Llallagua district. The area adjacent to the Monserrat mine is underlain by thin-bedded shale somewhat variable in color but predominantly dark grey to black. The beds strike northwest and dip at low angles southwest, forming part of the northeast limb of a major syncline. A resistant sandstone formation, which underlies the black shale, crops out along a ridge east of the mine and also accounts for the high ridge to the west that was previously mentioned. No igneous rock of any kind is found at Monserrat. The nearest intrusive bodies known are the irregular dikes and masses of quartz porphyry at Avicaya about 10 km to the south. Mine Workings The Monserrat property includes one main vein, which can be followed on the surface for 1600 m, and two or three branch veins of distinctly minor importance. The principal haulage tunnel, referred to as the San Carlos adit or level III, extends northeasterly for 1700 m, following the main vein throughout most of this distance. Above the adit, there are

Jan 1, 1951