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By Robert B. Schlosser

Anaconda's Jackpile uranium mine is a multi- million-ton open pit sandstone deposit, producing some 3000 tpd for the company mill. With minor exceptions, the orebody is in equilibrium, and the backbone of ore-grade control is the radiometric assay, which fortunately is dependable. Preparatory Sample Drilling: Before it is stripped, the orebody is diamond-drilled on 200-ft centers N-S and 100-ft centers E-W. Drill core is logged, split, and assayed radiometrically, and several samples are assayed chemically to check the equilibrium status. This information establishes the pit outline and the first rough estimate of ore. After stripping, diamond drill data is supplemented by rotary drillholes on 50-ft centers. Dry chip samples, collected every 2 ft, are prepared and assayed radiometrically at the mine. Details of the orebody are then available for study, and the basic mining plan is drawn up.

Jan 10, 1958

By F. H. Ellinger

TI HE crystal structure of neodymium has been re-A ported by Quill1 and by Klemm and Bommer"s to be hexagonal-close-packed, Strukturbericht-type A3, with a, = 3.650.4, c, = 5.890.4, c/a = 1.614. Klemm and Bommer,% owever, pointed out that the observed intensities of the lines of the neodymium powder pattern agreed only in part with the intensities calculated for the type A3 structure, and that the neodymium powder pattern showed extra lines which could not be traced to impurities. They found that these extra lines could be accounted for by doubling the c-axis, but apparently they did not consider their evidence to be sufficiently conclusive to justify reporting the doubled c-axis. In the present work, the structure of neodymium was found to be double hexagonal-close-packed. The neodymium metal used in the present investigation was obtained through the courtesy of F. H. Spedding of the Ames Laboratory. Its major impurity was stated to be 0.03 pct Ca. The author's spectrographic analysis indicated high purity and carbon was determined to be less than 30 ppm. X-ray powder specimens were prepared from filings stress relieved in vacuum at 200°C for 50 hr. Powder photographs were taken in an 114.6 mm diam camera (Straumanis film mounting) at room temperature and in a 19 cm diam Unicam high temperature camera at elevated temperatures. Copper x-radia-tion was used for all the photographs. The powder pattern of neodymium was found to index to a hexagonal unit cell with dimensions, as determined from the high angle Ka doublets, of: a.= 3.655+0.001.4; c, = 11.796+0.004.4; and c/a = 3.227 at room temperature. The measured density of neodymium shows that this cell contains 4 atoms, the calculated density is accordingly D, = 7.02 g per cu cm. The diffraction data for the first 15 lines of the powder pattern are listed in Table I. In a double hexagonal-close-packed unit cell, the 4 atoms would be in the positions (0,0,0), (0,0,%), (1/3, 2/3, 1/4), and (2/3,1/3,%) of space group P 6,/mmc. On the basis of these positions, the relative intensities of the reflections were calculated using the expression: 1+cos2 20 I oc \Frp 1 ' sin2 0 cos 0 where F is the structure factor and p is the multi- plicity factor. Since absorption was not taken into consideration, comparison of observed and calculated intensities should be made only for neighboring reflections. Each atom has 12 neighbors, 6 in the basal plane at a distance of 3.655.4 and 3 above and 3 below at the closer distance of 3.626.4. These distances correspond to an average radius of the neodymium atom of 1.820.4. The description of this structure in terms of A, B, and C close-packed layers of atoms is ABAC ABAC. ...... The structure repeats every fourth layer and the stacking sequence of the second, third, and fourth layers corresponds to cubic-close-packing of atoms. A series of powder photographs taken at successively increasing temperatures up to 680a10"C revealed that the double hexagonal-close-packed structure is stable up to this temperature. Acknowledgments The authw wishes to thank W. H. Zachariasen and A. S. Coffinberry for their helpful comments on this work and also Marion Gibbs for measuring the diffraction films. This work was sponsored by the United States Atomic Energy Commission.

Jan 1, 1956

By C. R. Ince

THE term "differential flotation" is used to denote a flotation operation in which separation is effected between two or more minerals of the same class; e. g., lead sulfide from zinc sulfide, pyrite from blende, chalcopyrite from pyrite, chalcopyrite from blende. At present, so far as published work shows, there seem to be two theories as to the mechanics of differential flotation. The earlier and more generally accepted theory is that the so-called depressing agents alter the surface of one or more of the sulfides in the ore, either by chemical action or adsorption, so that it is no longer amenable to flotation, but that these depressed sulfides can be revived, after the unaffected sulfide has been floated, by reagents which react chemically with the altered surface and make it amenable to flotation. More recently, Professor Taggart1 has advanced the theory that slime adsorption is an important factor in differential flotation. He believes that, with the proper use of a class of agents, which he calls .dispersion agents and which include practically all the depressing agents, one can cause the slime to adsorb differentially on sulfide surfaces. A gangue-slime coated sulfide surface will act as a gangue particle and will not float. If, subsequently, an agent that will remove the gangue-slime coating is added, the sulfide again assumes its original surface and can be floated as an ordinary sulfide. This-is the basis of the slime theory of differential flotation. Timber Butte mill at Butte, Mont., is a typical lead-zinc flotation concentrator. Neihart ore, chosen for investigation in this work, is one of the custom ores treated at that mill. Practice at Timber Butte mill in February, 1928, was as follows: A combined lead-zinc concentrate was first made using 0.2 lb. per ton on the ore of potassium xanthate and 0.03 lb. per ton of Cleveland Cliffs oil after 1.5 lb. per ton of lime and 1 lb. per ton of calcium chloride has been added just before the ball mill. The concentrate was then thickened to 70 per cent. solids. Potassium cyanide to the amount of 0.3 lb. per ton and zinc sulfate in the quantity of 0.5 lb. per ton were added to the thickened pulp and the whole

Jan 1, 1929

By Charles H. Snow

In vol. xxxviii. (1889) of the American Journal of Science, under the heading " Pseudomorphs of Native Copper after Azurite from Grant County, New Mexico," Mr. W. S. Yeates describes a most interesting mineral form. His account is, that a material having the appearance of native copper, but brittle and much lighter than native copper (its specific gravity being but 4.15), was submitted to him by the United States National Museum for examination. The substance was reported to him as occurring in masses, varying in weight from one ounce to seventy pounds, and composed of tabular crystals, variously grouped. The specimens, when submitted, ex hibited on the outride a covering of clay; and they were subse quently found to consist of particles of the same clay, intimately mixed with others of native copper, producing the aspect, without the weight, of pure copper. The forms of the azurite crystals, found at Bisbee, Arizona, having been suggested by the specimens, actual goniometer-measurements were made; and the two crystallizations were thus proved to be identical. To these statements I may be permitted to add some further in formation, derived from personal examination, and illustrated with a suite of characteristic specimens collected by myself (Fig. 2).* Grant County, New Mexico, in which these specimens were found, is a region noted for variety of mineral species. The sixth edition of Dana's Mineralogy mentions many of the silver, copper, and lead minerals, and also turquois, aragonite, wulfenite, barite, fluorite, vanadinite, etc. I have noticed also green and red garnet, molybdenite, native alum, smithsonite, bornite, etc., some of which presented peculiar modes of occurrence. The green garnet, for instance, was in masses formed of separate crystals, each of pea-size and not unlike that vegetable in tint and smooth opaqueness. The crystallization was

Jan 1, 1893

By G. V. Sullivan

This report describes an investigation by the Bureau of Mines of flotation techniques for the recovery of chromite from fine-grained disseminated ores. Reported work on the concentration of chromiferous materials shows that flotation has been applied almost exclusively to slime-free pulps. Therefore, chromium recoveries that could be obtained by flotation were related to the amount of slime rejected. However, results of recent studies by the Bureau of Mines showed that des liming is not a requisite to selective concentration of chromite. Laboratory-scale tests on seven ore types from the more important chromium-bearing areas of the Pacific Northwest showed flotation to be technically feasible for treatment of all but one of the samples. Concentrate grades were affected more by the composition of the chromite mineral than by the grade or character of the ore. Test results from three of the samples showed that, without prior desliming of the pulp, 78 to 91 percent of the chromium could be recovered in concentrates of 90 percent or more chromite; two samples responded to similar treatment, resulting in concentrates of more than 80 percent chromite with recoveries of 85 and 89 percent chromium. One sample of mill products, subjected to severe weathering, required removal of the primary slime to obtain a concentrate of 65 percent chromite with only 75 percent chromium recovery.

Jan 1, 1960

By W. S. Gresley

The traces of fossils herein described were discovered in or upon piles or heaps of iron-ores upon the docks at Erie, Pa. The author has worked among these ore-piles since 1890, when his attention was first directed to what looked like organic remains upon certain specimens collected. All the specimens described and figured herein were found by him, and, as no ironore is used at Erie, and no other iron-ores, save those of the Lake Superior region, find their way to the stock-piles at this place, there can be no question but that the specimens in question are genuine ore transported from that region over the great lakes, and cannot have been brought in from other ironore regions. The author has reason to think that no fossil remains have been reported hitherto as occurring in the iron-ores of the Lake Superior region, and he believes that these specimens, however imperfect, rank among the oldest forms of which man has any knowledge. The illustrations are engraved from photographs of drawings. The specimens themselves have not been photographed, because their condition would have prevented bringing out, by that process of reproduction, all the markings as clearly as is necessary, and would have rendered the specimens otherwise less distinct by reason of the blotchy character of their colors, the presence of cracks, or of marks more or less in contact with those of the organisms. In drawing these remains, therefore, I left out everything upon the specimens of ore that did not seem to belong in any way or contribute to their value as illustrations of the fossils. According to information obtained from the dock superintendent at Erie, Pa., the majority of these specimens came from the Chapin mine, Iron Mountain, Menominee range, Mich. As to the rest of them, I stupidly failed

Jan 1, 1897

By Robert C. Speck

Floor heave or deformation of the mine floor into the mine opening is a problem which has plagued coal mines in this country and others. In mining areas where room and pillar mining is practiced, floor heave generally occurs when the stress applied to the floor material by a coal pillar exceeds the bearing capacity of the floor strata. When the floor strata beneath the coal pillar fail, the pillar moves downward and displaces the material under it. This material, in turn, moves outward and upward into the mine opening (Figure 1). As the underlying materials fail, the load supported by the coal pillar may be transferred to adjacent pillars. If these are marginally stable, they too may become overloaded and push into the floor. Thus, floor heave can spread through a large portion of the mine in a progressive manner. As the pillars push into the floor, differential movement and flexure of the roof strata may cause them to weaken and fail, resulting in subsidence of the ground surface above the mine. This paper describes the problem as it was manifested in the Zeigler Coal Company No. 5 and Murdock room and pillar coal mines near Murdock, Illinois, and reports the results of a U. S. Bureau of Mines- sponsored study conducted by the University of Missouri-Rolla. During the course of the study, floor heave in the two mines hindered the transportation of men, machines, and coal to and from the working mine-face, interrupted ventilation plans, drastically increased roadway maintenance costs, intensified safety and strata control problems, destroyed large pieces of equipment, and, several times, pre- vented access to otherwise minable coal resources. The ultimate objective of the study was to develop one or more simple procedures to allow detection of a potential floor heave problem during the exploration phase of mine design--before initiation of production mining.

Jan 1, 1981

By Pei-Yung Huang, Carle R. Hayward

IN order to understand more fully the actual state of copper lost in copper reverberatory slags, a systematic study on the various reactions between certain metallurgically important copper compounds and synthetic copper reverberatory slags was undertaken by the authors in the Massachusetts Institute of Technology from 1942 to 1945.1 This paper, being only a part of the work completed, is published first because it furnishes the first experimental evidence of the formation of copper ferrite from reactions between cuprous oxide and copper reverberatory slags. CHOICE OF SLAG COMPOSITION The choice of the composition of the synthetic reverberatory slags to be used was much deliberated. Commercial copper reverberatory slags, neglecting minor constituents, average:2.3 45 to 47 pct FeO; 38 to 42 pct Si02; 5 to 6 pct CaO; 5 to 6 pct A1203. Since the ternary system CaO-FeO-SiO2 has been much more thoroughly studied4 and is much simpler than the quaternary system CaO-FeO-Si02-A1203, it was decided to use calcium oxide only instead of calcium oxide and alumina in the synthesis of the slags. Fortunately the composition of the average copper reverberatory slag with calcium oxide substituted for alumina lies in the region of the phase diagram clarified by the investigators. A survey of the phase diagram (Fig I) suggested two compositions: (I) the com¬position near the invariant point S, which is made up of 46 pct ferrous oxide, 37 pct silica and 17 pct calcium oxide; (2) the composition near the invariant point K with 45.5 pct ferrous oxide, 43 pct silica and 11.5 pct calcium oxide. Composition S has the advantage that the percentages of ferrous oxide and of silica almost exactly coincide with those of the average reverberatory slags, and that of the lowest melting point (1093° ± 3°C) in the whole ternary system. The calcium oxide content, however, obviously is high. Since we have already substituted calcium oxide for alumina, and since calcium oxide is more basic than alumina, the resulting slag is decidedly too basic. Composition K has a slightly higher melting point (1105° ± 3°C) and a higher silica content, but this is preferred because the slag is saturated with respect to tridymite and thus should not corrode siliceous refractories. Besides, it is less basic than composition S. The final slag composition, therefore, was chosen to

Jan 1, 1947

By Edward F. Fitzhugh

Quantitative appraisal of the chances of finding various tonnages and grades of ore clarifies any exploratory development proposal. Ways are discussed of appraising chances in conformance with probability principles, and graphs are suggested to show tonnages, grades and the corresponding judged expectancies. Introduction When exploratory development of a mineral deposit is contemplated, three interrelated questions normally must be answered before a sound decision can be reached. How much will the program cost? How much will the anticipated ore add to the immediate value of the mine? And what is the chance of developing this ore? To justify development, the deposit should present a favorable disparity between the three factors, cost, chance and return. If, for example, there is a 50-50 chance of success, the ore that is sought should have an immediate worth (after deducting all subsequent charges that it must bear) of more than twice the cost of the development. Likewise, if the chance of finding the ore is but one in five, that ore should enhance the immediate value of the mine by more than five times the cost of developing it- With sound economic and operating assumptions, the cost of exploratory development and a present value of anticipated ore may be estimated within reasonable limits. Less general attention has been given to appraising ore chances in comparable terms. The exploratory experience of the mining industry is broad enough that knowledge, vision and judgment may be combined to yield more tangible evaluations of Ore expectancy than are now customary' A way of making such appraisals is suggested herein. The mathematics of probabilities cannot be applied directly to the search for ore. By coupling applicable principles of probability, however, with pertinent experience gained in mineral exploration, an estimate often can be made of the chance of finding a certain tonnage and grade of Ore in a specific location. Such estimated, or judged, expectancies for the several blocks of ground in a deposit may be combined in a simple chart to show the relationship of the various exploratory possibilities and the potential magnitude of the deposit' An engineer or geologist may find that the quantitative thinking required for an appraisal of this type is an aid in clarifying and coordinating his views and recommendations. For a person wishing to understand these views, an ore-expectancy

Jan 1, 1949

By Edward F. Fitzhugh

Quantitative appraisal of the chances of finding various tonnages and grades of ore clarifies any exploratory development proposal. Ways are discussed of appraising chances in conformance with probability principles, and graphs are suggested to show tonnages, grades and the corresponding judged expectancies. Introduction When exploratory development of a mineral deposit is contemplated, three interrelated questions normally must be answered before a sound decision can be reached. How much will the program cost? How much will the anticipated ore add to the immediate value of the mine? And what is the chance of developing this ore? To justify development, the deposit should present a favorable disparity between the three factors, cost, chance and return. If, for example, there is a 50-50 chance of success, the ore that is sought should have an immediate worth (after deducting all subsequent charges that it must bear) of more than twice the cost of the development. Likewise, if the chance of finding the ore is but one in five, that ore should enhance the immediate value of the mine by more than five times the cost of developing it- With sound economic and operating assumptions, the cost of exploratory development and a present value of anticipated ore may be estimated within reasonable limits. Less general attention has been given to appraising ore chances in comparable terms. The exploratory experience of the mining industry is broad enough that knowledge, vision and judgment may be combined to yield more tangible evaluations of Ore expectancy than are now customary' A way of making such appraisals is suggested herein. The mathematics of probabilities cannot be applied directly to the search for ore. By coupling applicable principles of probability, however, with pertinent experience gained in mineral exploration, an estimate often can be made of the chance of finding a certain tonnage and grade of Ore in a specific location. Such estimated, or judged, expectancies for the several blocks of ground in a deposit may be combined in a simple chart to show the relationship of the various exploratory possibilities and the potential magnitude of the deposit' An engineer or geologist may find that the quantitative thinking required for an appraisal of this type is an aid in clarifying and coordinating his views and recommendations. For a person wishing to understand these views, an ore-expectancy

Jan 1, 1949

By Alan C. Noble

Ore reserves are often less than 30% of geologic resource estimates that are initially prepared by exploration geologists. Differences of this magnitude between resources and reserves can lead to serious . problems in the early valuation of properties when the geologic resource estimates are interpreted to represent ore reserves and are later found to be misleading and gross overstatements of ore reserves. The geologist can avoid such difficulties by considering the implications of mining, metallurgical recovery, and economics early in the project and by using appropriate qualifiers in the resource statement Examples using typical deposit characteristics are used to demonstrate how cutoff grade, stripping ratio, dilution, mining extraction and metallurgical recovery affect ore reserve estimations.

Jan 1, 1992

By R. L. Templin

THE modulus of elasticity is defined as the ratio of stress within the proportional limit to corresponding strain. This property, as thus defined, is a constant for each kind of material; and in tension or compression is usually designated by the symbol E. The modulus of elasticity serves as an index of the stiffness of a material or a measure of its ability to resist change of shape under stresses not higher than the proportional limit. In view of the frequency with which the modulus of elasticity is used in engineering calculations, it is surprising to note the uncertainty that exists as to authentic values, and the marked lack of published information relating to the variation of the constant E within individual alloy systems. A value of 10,000,000 lb. per sq. in. has been quoted as representative of aluminum and its alloys. This value has been found to be approximately correct for pure aluminum and aluminum alloys in which the total percentage of the alloying elements is low, but seriously in error in the case of alloys that contain relatively large amounts of the alloying elements.

Jan 1, 1930

By Atsuo Inoue, Toshihiro Ogata, Hideaki Sugihara

Generally in Japan, since ANFO has easy handling and low-price, it is most used as industrial explosives. However, ANFO is very easy to dissolve in water, it is difficult to use under existence of water and the consumer have desired water-resistant ANFO which has perfect water resistance. Then, we have developed the Water-Resistant Granular Explosive (It is written as following WRGE.) in which the surface of the explosive was covered by waterproof film, so that WRGE is able to use in hole with water. We ran various performance tests about the WRGE developed in the laboratory. Consequently, WRGE has water resistance of over 6 hours, and it has been checked that a performance and handleability were equivalent to the conventional ANFO. Then, we carried out the field test in the consumption site, and did performance evaluation on an on-site level. As compared with ANFO, fragmentation (size and volume) and handleability are almost equivalent. However, some problems which the WRGE is not settled out smoothly in hole with water and need more time for loading were also clarified. We are going to continue some advanced improvements through field tests.

Jan 1, 2005

By E. H. Sellards

PHOSPHATE rock like most other mineral substances is found in nature in varying degrees of purity. Of the impurities that are present some are constituents of the rock itself; others are inclusions of a foreign substance within the rock; while still others represent merely associated materials or minerals, either clinging to the rock or found in cavities and natural depressions, and hence largely removed in mining. Some of these impurities are distinctly deleterious to the processes of manufacture for which the phosphate is mined, while others, although neutral in action or nearly so, yet by their presence reduce the average grade of the rock and thus acid useless bulk to the shipment. It is the object of refined processes of mining to bring the product, as delivered from the mine, to the highest possible grade consistent with the market requirements and demands. This, however, is not accom-plished without actual loss in the form of discarded phosphate. It is evident, therefore, that the devising of methods for reducing this loss in mining, and yet maintaining the grade of the rock which the market requires, is one of the serious problems that the producers have to face.

Jan 9, 1914

By M. Q. Xu

During the flowsheet development for a potential commercial Cu/Ni separation plant at the In-co?s Sudbury operation, extensive laboratory and miniplant studies were carried out. There are two potential feed streams for Cu/Ni separation at the existing operation. It is shown that Cu/Ni separation from the rougher concentrate is relatively simple without need of regrind. However, Cu/Ni separation can be difficult from the bulk concentrate because of the presence of excess flotation reagents in the bulk concentrate slurry and locked particles. Excess flotation reagents created excess froth increasing entrainment. By replacing the slurry water with tap water and with addition of some hydrogen peroxide, entrainment is minimized and good Cu/Ni separation is achieved on the bulk concentrate. Fine regrind is required to increase liberation of the locked particles for ultimately high copper recovery at the minimal nickel content.

Jan 1, 2014

By Charles H. Shamel

I fear most of the Institute members are already weary of the perennial controversy about the apex law. I feel that way about it myself now, though I have been guilty of considerable contribution- to the discussion in the past. The discussion does not seem to perceptibly influence previously held views and I would not again break into print on the subject but for the urgent invitation of the Chairman of our Law Committee. This energetic and able member has firmly determined to secure a revision of the mining law and among other things to eliminate the so-called apex provision from the U. S. mining statutes. He is, however, fair about it and has invited me to make ((the strongest possible argument in its favor." I am suspicious that he is acting on the psychological principle that it is usually easier to convince an audience against a cause vigorously but unsuccessfully defended than against one wholly mute. Nevertheless, I realize that personally he wishes me no harm, much as he hates the apex law, and so am willing that the Institute have whatever benefit may accrue from my taking up again the unpopular side of the discussion. I say this because the attitude of a large part of our "articulate" membership seems irreconcilably hostile; their minds are made up; favorable consideration is foreclosed; and they become impatient and even sarcastic at any attempt to elucidate a favorable view of the apex law. The exact question for discussion at the present time is not whether on abstract, or any other considerations, the apex law is the best possible rule, but the very different proposition whether, after nearly 50 years of statutory life and much longer as a practically universal miners' custom, it is now just and expedient to repeal the apex law. At this point it seems to me that we may profitably devote a paragraph or two to the subject of the origin of law in general, as we are presumed to be considering the subject from the high viewpoint of the general welfare of the nation. The most comprehensive and accurate definition of law in the legal sense is, that it is the body of rules for the regulation of human conduct which is enforced by the State, that is, by the nation.l Legal

Jan 1, 1915

By Robert B. Hopler

Hercules Incorporated has designed, developed, and begun introducing a new non-electric delay blasting cap system which is radically different from anything presently available. This system, called Hercudet™, utilizes no wires or detonating cord. Instead, each cap has two plastic tubes attached to it. These tubes contain no coating or other materials other than dry nitrogen to extend storage life. In use, after connecting the tubes together with external sleeve connectors, the circuit is checked with a specially designed tester. When the blast area is cleared, the circuit is filled with a gas consisting of an automatically proportioned mixture of fuel and oxidizer gases. When the circuit is fully charged the gas is initiated by special means within the Hercudet™ blaster. The reaction that then travels throughout the circuit has no distruptive effect on the tubing, and virtually no noise is produced.

Jan 1, 1975

By Donald C. Clark

The Blasting Contractor as an Insurance Risk involves a discussion of changing times in the insurance market and changing methods of operation in the construction industry. Since the advent of Internal Revenue Service~1 and Occupational Safety and Health Act~2 regulations by the Federal Government in the early 1970's, operations have changed. Many small users of explosives have discontinued any use in favor of subcontracting the drilling and blasting to specialists. This change in operations along with the change in the insurance market has created coverage problems which is the subject of discussion of this paper. Although no definite conclusions are reached, it is an attempt to promote understanding and further the efforts toward equitable solutions.

Jan 1, 1977

By Juan P. Camus

One of the most important decisions in mine development is the selection of the mining method. Open pit or underground methods are selected depending on the shape of the deposit, and its position with respect to the surface. When the decision is not clear or evident, then the common rule is to compare underground and open pit projects to choose the one which yields the maximum return. However, in some circumstances' the best alternative is to start-up the operation with an open pit until a point where mine operating costs make more convenient to employ an underground method. In this case, the final pit limit is not directly related with commodity prices and its position is a funtion of capital and operating costs associated with both methods. The goal of this paper is a mans of establishing the proper ultimate pit considering a potential underground mine. The methodology is quite simple and can be implemented to work with a variety of available routines for pit optimization, such as Lerchs-Grossmann, floating cone, network flow and the Lemieux moving cone optimizing algorithm, which is the tool used by the author.

Jan 1, 1992

By C. J. P. Ball

Prior to 1939 the bulk of the magnesium metal produced outside of the united Stater was extracted directly from the ore and ifi the United States from magnesium chloride obtained as a by-product from the treatment of natural brines. A typical brine is one containing about 0.25 to 0.75 per cent bromine, 11 to 14 per cent sodium chloride, 9 to 11 per cent calcium chloride and 3 to 10 per cent magnesium chloride. The state of Nevada was known to possess large deposits of magnesite ore (MgCOs, the carbonate of magnesium), in Gabbs Valley, near Luning, approximately 350 miles north of Boulder Dam. Deposits mined in Europe were supplying magnesite giving 97 per cent MgCOs with about I per cent each of silica, lime and oxides of iron and aluminum. parts of the Luning de-posits Were almost equally rich, and the general average was of sufficiently high grade for production of magnesium. power to the amount of 200,000 kw. was available immediately from Boulder Dam, and water from Lake Mead, and it was this combination of available power, water, and ore that led to the initial proposal to erect a magnesium reduction plant in southern Nevada to reduce the magnesite ores from Gabbs. The extraction of magnesium metal from these magnesite deposits had been considered by the I. G. Farbenindustrie of Germany as far back as 1929. Mine and Oxide Plant The mine and oxide plant of Basic Magnesium Incorporated are perched upon the oride slope of the Paradise Range, at an altitude of 5000 ft., overlooking the 30 mile desert panorama of Gabbs Valley, Nevada. , Ore Occurrence The Gabbs magnesite ores occur in a thick series of flat, westerly dipping dolomites of Upper Triassic age. The mag-"esite bodies are exposed in steep canyon "areas encircling the north and east edges of a northerly projecting tongue of a roughly elliptical stock of granodiorite, which intrudes the dolomite. The magnesite mineralization is considered to be a a of calcium by magnesium through the agency of hydro-thermal solutions associated with the intrusion of the granodiorite. The ore bodies are of very irregular shape and distribution. Incomplete evidence points to deep pipelike replacement shapes that mushroom out erratically at various elevations. A wide latitude in the degree of magnesium replacement is reflected in a variance of quality from pure magnesite to magnesitic dolomite. The, ore is a massive crystalline mag-nesite. Though some differences in characteristics occur between ore bodies, in general the ore is a medium-grained carbonate varying in color from white, through all shades of gray, to black. Recrystallized dolomite, which encloses and occurs as

Jan 1, 1944