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By S. T. Wlodek

The scale md subscale reaction products were identified and their rates of formation were studied in air over the range 1600" to 2000°F (871 " to 1149°C) for periods of up to 400 hr and for hoth the solution-annealed and aged conditions. The effect of prior sltrface preparation on suhscale oxidation was also studied The general oxidation behavior of both Ni-Cr-Mo-Al-Ti type alloys was similar. A surface film of a, Al2O3, forms immediately on exposure Subsequent oxidation continued at a linear rate (QL = 55 * 5 kcal per mole) as colonies of Cr2O3 nucleated at the A12O3/gas interface Further oxidation proceeded at a paraholic rate zvhiclz could he fitted to two successive rate constants. During paraholic oxidation, and depending on temperature, the scale consisted of Cr2O3, NiCr2O4 , and TiO2 with traces of NiO. In the case of Rene 41, the activation energy of both paraholic processes was 66 * 3 kcal per mole suggesting that diffusion of cations tlzrozrgh Cr2O3 was the rate -determining process. An unusual decrease in the oxidation of Udimet 700 at 1900°F where a spinel of Ni(A1,Crh0, zuas the predominant reaction product prevented the accurate assignment of activation energies for this composition. In both alloys internal oxidation of Al2O3 commenced shortly after parabolic scaling was observed. Prolonged exposure prod7tced intemal oxidation of TiN, and in Udimet 700 a complex Mo-Ni nitride was also found. At 1900oF, the subscale reactions in Udimet 700 undergo an inversion which parallels the decrease in surface oxidation; internal oxidation ceases hut is replaced by the formation of "spherodized" 3.' colonies. Surface-preparation techniqtles which introduce appreciable working, such as coarse surface grinding or grit blasting. increase the amount of alloy depletion and internal oxidation in Reni 41. The reverse is true of Udimet 700 for which electropolished or mechanically polished specimens show much more subscale oxidation than strongly worked stirfaces. The strongest commercial nickel-base alloys presently available are generic to the Ni-Cr-Mo-A1-Ti base which exploits the precipitation of Ni3(A1,Ti) as the main strengthening mechanism, while relying on solid-solution strengthening by molybdenum and chromium reinforced by the pre- cipitation of carbides to attain maximum properties. This study characterizes the oxidation behavior of Rene 41, the strongest alloy of the Ni-Cr-A1-Ti type commercially available in sheet form, and Udimet 700, whose higher aluminum and titanium content allows it to exhibit one of the more attractive combinations of high-temperature properties available in a wrought product. The scaling processes of complex, type nickel-base alloys have received relatively little attention. Malamand and vidal as well as Poulignier et al.2'3 have determined the composition gradients across the metal/oxide interface produced by high-temperature oxidation and considered the effect of surface perature, Limited weight-gain data has also been published by Fere 5 for alloys of this type and Radavich6 has identified the reaction products on Udimet 500 and Inco 702 after oxidation at 1832°F. Reference can, of course, be made to the excellent reviews of Kubaschewski and Hopkins7 or Ignatov and Shamgunova8 for a summary of the data available on the oxidation of binary and ternary alloy systems which are related to the more complex alloys considered here. EXPERIMENTAL The analyses of the different commercial heats studied are given in Table I. Using the experimental procedures previously established,9 continuous weight-gain data were obtained on both heats of Rene 41 sheet (A and B) and 150-mil-thick slices of cast Udimet 700. Subscale oxidation reactions were followed by static exposure of cylindrical specimens obtained from swaged Rene 41 (Heat C) and Udimet 700 (Heats E and F). In brief, continuous weight-gain tests were performed on specimens with a surface area of 10 to 12 sq cm. These were abraded through 600 grit Sic paper, electropolished to 2p rms in an electrolyte of 10 pct H2So4 in ethanol, and lightly etched in 10 pct HCl in ethanol before final washing and rinsing in ethanol. All continuous weight-gain data were obtained in dried (-70°F dew point) flowing (1 liter per min) air to an accuracy of +0.1 mg. Subscale oxidation processes were followed by the metallographic examination of 0.5-in-diam by 1.0-in.-long specimens. After an initial center-less grinding, various additional surface treatments were employed to determine the effect of surface preparation on subscale oxidation processes. Before exposure in zirconia crucibles, all samples were lightly etched in 10 pct HCl-ethanol, washed in ethanol, and dried. The depth of internal oxidation was measured to ±0.00025 in. on unetched specimens mounted so as to provide a taper mag-

Jan 1, 1964

By Frederick Rhines

PURE copper that has been allowed to oxidize at an elevated tempera-ture in the air is found to be covered with two distinguishable layers of oxide scale. The outer of these, which is very thin, is composed of cupric oxide, while the inner layer, comprising the bulk of the scale, is made up chiefly of cuprous oxide (Fig. 1a). If a small quantity of an alloying element, such as silicon, is present in the copper, silica particles are found disseminated through the cuprous oxide, deposited most abundantly near the metal surface, and, in addition, silica particles occur to a limited depth within the copper itself (Fig. 1b). It is this inner layer, composed of oxide particles precipitated in a matrix of metallic copper that is known as the "subscale" or the zone of internal oxidation. Under a low oxygen pressure it is possible to produce the subscale without the formation of external layers of copper oxides, thus leaving the metal surface bright and apparently clean while oxidation has occurred, in fact, to a considerable depth within the metal (Fig. 2). Although little is yet known in a detailed way of the mechanism of internal oxidation, the general nature of the process is evident. By virtue of the considerable solubility of oxygen in copper,1 it is possible to bring the alloying element in contact with oxygen within the metallic solid solution. If the oxide of the alloying element is more stable than cuprous oxide, the foreign oxide may form and, since most oxides are relatively insoluble in copper, it will not long remain in solution, but will separate as a precipitate. As the metallic solute is exhausted in the zone of precipitation, oxygen that is constantly being supplied at the surface diffuses farther into the alloy and thus produces an ever-thickening shell of subscale. The distribution of the reacting elements in the subscale and adjoining zones must be somewhat as indicated in Fig. 3. The conditions requisite to internal oxidation to be anticipated are thus: (1) a solubility of oxygen in the alloy, (2) the ability of oxygen to diffuse at an appreciable rate into the alloy, (3) the possibility of the

Jan 1, 1940

By Thomas B. Douglas

INSTRUMENTATION in the process industries can no longer be regarded as a convenience, but rather an absolute necessity. Although many chemical processes must already be conducted with instruments, every properly designed application of automatic process control will improve operation: 1) the product will be more uniform and of higher quality; 2) the manual labor saved will reduce cost; 3) uniformity of flow and uniform control of process will increase production; and 4) surges will be eliminated, making it possible to operate equipment near ultimate capacity at all times. Industrial instruments fall into two general classifications—those that measure and those that measure and control. The cement industry has been using instruments for a number of years, particularly in the burning process, primarily for indicatlng and recording. Automatic process control makes additional use of these instruments, and others, to control variables. Assisted by the instrument manufacturers, engineers at Ideal Cement Co. achieved considerable progress in determining how well the usual recording instruments could be made to control various phases of cement-making. The results of these experiments were used to make the new plant at Houston as wholly automatic as possible. The original Houston plant, built in 1937 by Gulf Portland Cement Co., consisted of only one 8 x 220-ft kiln and the necessary grinding mills and accessory equipment and had a capacity of 900 bbl per day (300,000 bbl annually). Ideal Cement Co. purchased this plant in 1940 and almost immediately started plans to increase its production. In 1941 a 9 x 220-ft kiln was installed and grinding and storage capacity were increased. The growing demand for cement in the Houston area necessitated a third kiln (9 ft 6 in. x 250 ft) in 1947. This brought the plant up to its present capacity of about 1.3 million bbl per year. Calcium silicates in cement are produced in a burning operation at high temperatures from raw mix of argillaceous and calcareous materials that have been crushed, mixed, and ground to a fine powder. The composition of this mixture must be kept consistent within narrow limits. Raw mixing and grinding may be done either wet or dry, but in both instances the materials must be correctly proportioned, finely ground, and thoroughly intermixed before entering the kiln. As the raw mix passes through a long horizontal rotary

Jan 1, 1959

By William P. Shinn

IT seems proper to present in the Transactions of the Institute, from time to time, formal record of the advances made in the arts and sciences to which our organization is devoted-milestones in the highway of progress-from which our successors may measure what they in their turn have gained. The admirable address of the Hon. Abram S. Hewitt, then president elect of the Institute, on "A Century of Mining and Metallurgy in the United States," read at the opening of the meeting held in this hall in June, 1876, forms a point of departure, and the conclusion of the eighth decade of the nineteenth century and the end of the first five years of our country's second century seem to offer a fitting time for again making up our record. The period since 1875 has been marked by a degree of activity in mining and metallurgical industry never before equalled in our history, while the progress made in the science and art has been, if possible, still more noticeable. Whether we consider the mining of iron, ore, and coal, or of the precious metals,-the advances made in smelting the former and in reducing the latter, the extraordinary increase in the production of Bessemer steel, or the science of Thomas and. Gilchrist, which makes the hitherto rejected phosphorus the corner-stone of success,-the past five years are alike memorable for the progress they have shown and to some of the most marked features of this progress I will now oriefly call your attention. It may be of interest in this connection to note the following figures, showing the growth of the population of the United-States during the last three decades :

Jan 1, 1881

The accompanying sketch shows the interesting position of Salt Lake City with reference to Western mining areas and justifies its title "The Center of Western Mining." In the last twenty years, the area embraced within a circle of 600 miles radius with Salt Lake City as its center has produced 79.87% of the gold, 91.9% of the Silver, 77.47% of the copper, 53.61% of the lead and 26.55% of the zinc produced in the United States, including Alaska. This area also contains the greatest coal deposits of the continent, some of the greatest oil deposits, great iron deposits and many other important mineral resources. The 600-mile circle contained 69% of the active operators of other than coal mines and 40% of the men employed in mines other than coal mines of the United States, including Alaska, for the four-year period ended with 1923.

Jan 1, 1925

The Industrial Minerals Division met jointly with the Materials and Equipment Division of the American Ceramic Society at State College, Pa, Sept 24-26 Headquarters were at the Nittany Lion Inn Thurs- day afternoon was devoted to a tour of inspection of the Bell Mine, American Lime and Stone Co , Bellefonte, Pa The party returned to State College for dinner and in the evening the Division's executive committee held a brief session There were four technical sessions Friday morning, Mining, afternoon, Beneficiation, Saturday morning, Industrial Minerals and Beneficiation There was an informal banquet at the Nittany Lion Inn Friday night with 93 present Edward Steidle was toastmaster Brief talks were made by President F C Flint and Secretary Ross Purdy, of the American Ceramic Society, Oliver Bowles, Chairman, Industrial Minerals Division, Adrian Morse, assistant to the president, Pennsylvania State College, and George Otis Smith, past president A I R'I E

Jan 1, 1937

On Sept. 22 to 26, the Institute will hold its 120th meeting in Chicago. The program arranged provides for technical sessions on: Mine Taxation, Non-ferrous Metallography, Coal and Gas, Milling, Oil, Industrial Organization, Geology, Non-ferrous Metallurgy, Mining and Local Resources, Iron and Steel, Symposium on Sulfur Coals, Symposium on Pyrometry. Inspection trips have been arranged to: Gary Steel Plant. La Salle District: Zinc smelters, coal mines, cement works, America's first permanganate plant, many varied industries, scenic trips. North Chicago and Milwaukee: Mining-machinery manufacturing plants, tungsten and molybdenum reduction plants. East Chicago and Whiting: Lead refinery, oil refinery. Franklin and McCoupin: Coal fields. Chicago: Nearly every kind of metallurgical and manufacturing industry. MONDAY, SEPT. 22d Morning Registration, Non-ferrous Metallurgy, Coal and Gas. Afternoon Coal and Gas Milling Industrial Geology, etc. Evening Smoker. TUESDAY Morning Gary. Afternoon Gary. Iron and Steel. Evening Oil, Iron and Steel.

Jan 9, 1919

By AIME AIME

Further details of the 97th meeting of the Institute, at Spokane, have been sent to members in the Special Circular of May 8, 1909, and for convenience a summary of the additional information is given later in this announcement. In spite of the present small number who have joined the party, final arrangements have been made to complete the itinerary given in the circular. It is greatly to be desired, both in behalf of the Institute and in recognition of the special courtesies to be extended on the trip, that the party be made larger. Exceptional facilities to visit the many mines and smelters have been freely provided; and members are requested to make all reasonable effort to attend the meeting at Spokane and participate in the excursions. . For those who cannot take the entire trip, it may be possible to provide special Pullman accommodations after leaving the Yellowstone Park. In order to make the necessary arrangements, however, the names of members and guests contemplating this partial trip should be sent at once to Mr. Theodore Dwight, .39 West 39th St., New York, N. Y. A special train of Pullman cars will leave Chicago September 16. This train will be side-tracked at all places visited, and the sleepers will be available for lodging and the dining-car for meals (luring the entire trip, except while taking the tour through the Yellowstone Park. The general cost of the trip per member will be $300, which includes transportation, berth, and meals for the entire trip from Chicago back to Chicago, almost 6,000 miles, and the tour through Yellowstone Park, occupying in all about 30 days. Special accommodations on the train will be furnished at the following rates

Aug 1, 1909

By Alfred H. Bell

The upswing in oil production and drilling activity in Illinois that began in 1937 gained momentum in 1938 and promises to bring a new and higher peak in the state's annual production in 1939. In 1938 the production totaled 23,929,000 bbl., as compared with 7,426,000 bbl. in 1937, more than a threefold increase. The number of producing oil wells in the new fields was 230 at the end of 1937 and it increased to 2157 at the end of 1938. Daily production for the whole state increased from approximately 35,000 bbl. at the end of 1937 to approximately 135,000 bbl. at the end of 1938, nearly a fourfold increase. Of a total of 2539 wells completed in 1938 in Illinois, 1984 produced oil, 26 produced gas and 529 were dry holes. Of the total, 377 are classified as "wildcat" wells, defined as wells drilled outside of proved territory and more than one mile from the nearest production. The remainder, 2162 wells, were drilled in or near proved fields. Of the 377 wildcat wells (Table 2) 32 were successful in discovering oil or gas in commercial quantities, either new fields or extensions of old fields. Four of these discovery wells mere gas wells, which are not yet commercially productive owing to lack of pipe-line facilities. A special effort was made to ascertain the reasons for the locations of as many as possible of the wildcat wells and the results of this investigation are set forth in the following table:

Jan 1, 1939

By Alfred H. Bell

The upswing in oil production and drilling activity in Illinois that began in 1937 gained momentum in 1938 and promises to bring a new and higher peak in the state's annual production in 1939. In 1938 the production totaled 23,929,000 bbl., as compared with 7,426,000 bbl. in 1937, more than a threefold increase. The number of producing oil wells in the new fields was 230 at the end of 1937 and it increased to 2157 at the end of 1938. Daily production for the whole state increased from approximately 35,000 bbl. at the end of 1937 to approximately 135,000 bbl. at the end of 1938, nearly a fourfold increase. Of a total of 2539 wells completed in 1938 in Illinois, 1984 produced oil, 26 produced gas and 529 were dry holes. Of the total, 377 are classified as "wildcat" wells, defined as wells drilled outside of proved territory and more than one mile from the nearest production. The remainder, 2162 wells, were drilled in or near proved fields. Of the 377 wildcat wells (Table 2) 32 were successful in discovering oil or gas in commercial quantities, either new fields or extensions of old fields. Four of these discovery wells mere gas wells, which are not yet commercially productive owing to lack of pipe-line facilities. A special effort was made to ascertain the reasons for the locations of as many as possible of the wildcat wells and the results of this investigation are set forth in the following table:

Jan 1, 1939

By J. M. GLEDHILL

(Washington Meeting, May, 1905.) A Discussion of Mr. J. M. Gledhill's paper, read by title at the Lake Superior meeting, but presented first at the New Yolk meeting of the Iron and Steel Institute (October, 1904), and here published under a mutual agreement. Between the two Institutes. Discussion. MR. E: WINDSOR RICHARDS, Past-President, said that at a recent meeting of the Institution of Mechanical Engineers a paper was read on tool steel, and he called the attention of the members to the high-speed tool steel at the Bethlehem Works. They would have the pleasure of seeing those wonderful works and would see 60, 70, 80 and 100 tons oil lathe with half-a-dozen of these high-speed tools running. PROP. H. M. HOWE (Columbia University) said that they all looked upon these high-speed tool steels as of very great importance, particularly to the machine shop. One point occurred to hire : Had it really been shown that Swedish steel is necessary, or better than equally pure steel that is not Swedish; and is cemented steel really necessary, and is there any advantage in using that, rather than equally pure open-hearth steel'! It might be well if the author could indicate the kind of evidence on which lie bases his assertion that it is necessary to have cemented Swedish steel. Many were hoping for the development of high-speed steels from elements which exist in great quantities, such as silicon, manganese and chromium, rather than from rarer metals like molybdenum, vanadium and tungsten, the supply of which is likely to be soon exhausted. If the high-cutting speed was to last more than a generation, it. seemed to him that they would have to draw upon the common ele¬ments and not upon the rare ones. MR. Tom WESTGARTH (Middlesbrough) said he fully appreci¬ated what had been said about the advantages of using high-speed steel, because great benefit had been derived from the

Mar 1, 1905

By Eugene McAuliffe

AS anthracite is no longer used to a marked extent by the rail- ways of the United States (1,513,000 tons in 1933), that portion of the mining industry engaged in the production of bituminous coal is, and will continue to be, the one chiefly concerned with the future use of its product by the railways. In a period such as the present, when all enter- prise is unsettled, when fundamental principles of industrial management and control are being swept aside or else changed overnight, it is difficult to predict what will happen. The relation between the total production of bituminous coal and the volume consumed by the steam rail- ways of the United States, Classes I,

Jan 1, 1936

By AIME AIME

AT FOUR O'CLOCK members gathered in the auditorium for the annual business meeting of the Institute which, according to its charter, must be held on the third Tuesday of February each year. President Turner presided and after the usual formal action on minutes announced that he would create a precedent by transferring the President's annual address (which by tradition has always been delivered at the banquet on Wednesday evening) to the business meeting, and, furthermore, would only present a brief abstract of it. Since it appears in full on pages 127-131 of this issue it can be followed with the careful attention its thoughtful analysis of current conditions deserves.

Jan 1, 1933

By Sherwin F. Kelly

SINCE we used Chief Buehler's name last year to give our annual report a semblance of respectability, we can follow the good precedent thus established by telling of the work his Missouri State organization has been carrying on, as reported by H. S. McQueen. Considerable value is set upon their magrletorneter working which has covered over 13,000 sq. mi.), for the indications it gives of the major structural features of the region. Numerous geological problems have been tackled Ly resistivity techniques, among which are the locating and outlining of filled sink deposits of sulphides, of iron ore, and of fire clay; tracing of faults and solution channels; mapping of the preglacial structural pattern; measurement of depth of overburden; and

Jan 1, 1937

By J. J. Forbes

Probably the newest thing in mining safety, or safety for mines, is the apparent dissatisfaction on the part of the mineral industries, as represented by both management and labor, and the general public of the Nation, with the safety record of the mining industry. This is reflected by published comments and papers in the technical press;1-8 in labor periodicals, 10 11 in popular journals and periodicals,12 13 and in the daily press; also by discussions of the Safety Committees sponsored by the National Safety Council, 9, 14-15 the American Mining Congress, 1, 16 the American Institute of Mining and Metallurgical Engineers, 2, 4 the Mine Inspectors' Institute of America,6,8,17,18 the Coal Mining Institute of America, 5, 19, the American Standards Association, and others.20,21

Jan 1, 1949

By Verne C. Fryklund, S. Warren Hobbs

The Coeur d'Alene district in the panhandle of Idaho is one of the major lead-zinc-silver producing areas in the world. The value of recorded production to date has exceeded $2 billion. Country rock comprises six formations of the fine-grained, highly siliceous, and slightly metamorphosed Precambrian Belt Series. Small stocks of monzonitic rocks and several varieties of dikes intrude the sediments. The district is at the intersection of a north trending major anticlinal uplift and the west northwest-trending Lewis and Clark line of which the Osburn fault is the dominant feature. The district structure is complicated and comprises folds, some of which are overturned, and a complex of faults of diverse ages and directions of movement. Late Cretaceous stocks but are also probably Cretaceous in age. The productive veins are localized within a series of 12 subparallel, straight mineral belts that trend approximately N65°W and that appear to be controlled by deep fractures in the basement rocks. The mineral belts are in two groups, separated by 15 miles of post-mineralization movement on the Osburn fault. Veins and ore shoots are variously disposed within each mineral belt. Many crop out at the surface, but others apex several thousand feet beneath it. Local controls that influence the position of ore shoots within the mineral belts include the brittle character of host rock attitude of bedding relative to the mineralized fracture, and the amount and direction of movement on faults. Depth appears to have had little effect on the occurrence or type of ore. Ore occurs in a series of steeply dipping replacement veins of relatively simple mineralogy. Six periods of mineralization, ranging from Precambrian to Tertiary in age, are recognized. The productive galena sphalerite-bearing and tetrahedrite-bearing veins-of the main period of mineralization-are younger than the

Jan 1, 1968

By F. L. Sizer

SOME old-time views which have recently come into my possession have inspired me to record that part of the early history of Leadville, Color- ado, with which I am familiar, the years 1878 to 1882, in the hope that others will add to what is here mentioned. My first appearance in Leadville was in June, 1878, immediately after graduation from the University of Michigan, and I found a congenial and lively crowd of young men, already there. The old log hotel, at the corner of Pine and State streets, housed some distinguished guests in the summer and fall of 1878. It was my good fortune there to make the acquaintance of James B. Grant, afterwards Governor of Colorado, in July of that year, when we were both glad of the accommodation afforded by cots in the second floor loft of the hostelry presided over by Herman Hibschle. Grant was then building his smelter and our associates were Eddy and James, August R. Meyer, and Berdell and Witherell. The Grand Hotel-Harris and Walsh, pro- prietors-was the first-class hotel of the place; but in a very few months there were many competitors.

Jan 1, 1924

By J. P. Smith

DURING the winter of 1946 to 1947 potash operations in Germany, France and Spain were visited by the author. The U. S. Department of Commerce, through its Field Intelligence Agency Technical, sponsored the inspection of German properties by representatives of the American Potash Industry. Vast deposits of potash salts occur in the above-mentioned countries, and the production and marketing of these salts are important in their respective economies. Germany An area of some ten thousand square miles of north central Germany is underlain by lenses of potash salts interbedded with greater thicknesses of sodium chloride or common salt. These salt measures are relict deposits from the evaporation of an arm of the Zechstein (Permian) Sea which formerly covered northern Europe. During the peak year of 1940, Germany produced salts containing 1,860,000 tons of K,O and, next to coal, potash is its most important mineral raw material. The German deposits are found in the synclinal areas flanking the Flechtingen, Hartz Mountain and Thuringian uplifts, and, to the north they lie beneath the plains of Hannover. The regional dip of the salt measures is to the north, hence, lenses of potash found at depths of 500 to 1000 m* in the Two general depositional provinces of potash concentrations are recognized: (1) the main basin, and (2) the subsidiary basin. The main basin embraces the producing districts of Stassfurt, Sud Hartz, Halle, and Hannover-Braunschweig. From J. P. SMITH, Member AIME, is Clzief Geologist, U. S. Potash Co., Carlsbad, New Mexico. New York Meeting, February 1948. TP 2621 H. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received May 26, 1948. 40 to 45 pct of the German production comes from this basin. The Werra-Fulda district, producer of 50 pct or more of the German potash, lies in the subsidiary basin. Salt Stratigraphy: Five commercial potash zones or beds are recognized. The three beds present in the main basin are: The Stassfurt bed that occurs near the top of the older salt, and the Ronnenberg and Riedel beds in the younger salt occurring 200 to 300 m, respectively, above the Stassfurt bed. The Stassfurt bed is found over the entire main basin, while the Ronnenberg and Riedel are restricted to the Hannover area. Two potash beds occur in the Werra basin. These are the Thuringian, or lower bed and the Hessen or upper potash bed that occurs 60 m above. These beds lie 210 and 150 m, respectively, below the position of the Stassfurt bed, and are restricted to the Werra basin. The upper bed is 2.5 to 11.5 m in thickness, and the principal ores are hartsalz with varying thicknesses of carnallite. The lower bed averages 3 m in thickness, and contains hartsalz. The upper bed is presently being mined, and the

Jan 1, 1951

By J. P. Smith

DURING the winter of 1946 to 1947 potash operations in Germany, France and Spain were visited by the author. The U. S. Department of Commerce, through its Field Intelligence Agency Technical, sponsored the inspection of German properties by representatives of the American Potash Industry. Vast deposits of potash salts occur in the above-mentioned countries, and the production and marketing of these salts are important in their respective economies. Germany An area of some ten thousand square miles of north central Germany is underlain by lenses of potash salts interbedded with greater thicknesses of sodium chloride or common salt. These salt measures are relict deposits from the evaporation of an arm of the Zechstein (Permian) Sea which formerly covered northern Europe. During the peak year of 1940, Germany produced salts containing 1,860,000 tons of K,O and, next to coal, potash is its most important mineral raw material. The German deposits are found in the synclinal areas flanking the Flechtingen, Hartz Mountain and Thuringian uplifts, and, to the north they lie beneath the plains of Hannover. The regional dip of the salt measures is to the north, hence, lenses of potash found at depths of 500 to 1000 m* in the Two general depositional provinces of potash concentrations are recognized: (1) the main basin, and (2) the subsidiary basin. The main basin embraces the producing districts of Stassfurt, Sud Hartz, Halle, and Hannover-Braunschweig. From J. P. SMITH, Member AIME, is Clzief Geologist, U. S. Potash Co., Carlsbad, New Mexico. New York Meeting, February 1948. TP 2621 H. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received May 26, 1948. 40 to 45 pct of the German production comes from this basin. The Werra-Fulda district, producer of 50 pct or more of the German potash, lies in the subsidiary basin. Salt Stratigraphy: Five commercial potash zones or beds are recognized. The three beds present in the main basin are: The Stassfurt bed that occurs near the top of the older salt, and the Ronnenberg and Riedel beds in the younger salt occurring 200 to 300 m, respectively, above the Stassfurt bed. The Stassfurt bed is found over the entire main basin, while the Ronnenberg and Riedel are restricted to the Hannover area. Two potash beds occur in the Werra basin. These are the Thuringian, or lower bed and the Hessen or upper potash bed that occurs 60 m above. These beds lie 210 and 150 m, respectively, below the position of the Stassfurt bed, and are restricted to the Werra basin. The upper bed is 2.5 to 11.5 m in thickness, and the principal ores are hartsalz with varying thicknesses of carnallite. The lower bed averages 3 m in thickness, and contains hartsalz. The upper bed is presently being mined, and the

Jan 1, 1951