POTASH IN THE PERMIAN SALT BASIN H.I. SMITH U. S. Geological Survey, Washington, D. C.
potash mineral, polyhalite, was identified in a well drilled for oil in Texas ; 4 years later sylvite was discovered in a well drilled for oil in New Mexico. After the discovery of sylvite, a mineral that contains approximately four times as much potash as polyhalite, active prospecting by core drilling was begun by both private and government agencies, and early in 1931 production of sylvite on a commercial scale began in the United States.
The Permian Salt Basin in Texas and New Mexico has long been considered by geologists as a potential source of potash for American needs. The salt horizons in which potash may occur lie at considerable depth from the surface, and the probability of making a discovery was lacking except at scattered locations where wells were drilled for water, oil, or gas. Potash was discovered in the brine of a well drilled for water in Texas in 1912. Nine years later the
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THROUGH SYLVITE DEPOSITS FIWJRE 1. CROSSSECTION EASTOF CARLSBAD, N. MEX. $,. ~
854
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HE Permian Salt Basin of New Mexico, Texas, Colorado, Oklahoma, and Kansas is largely a subsurface feature, the boundaries of which have not been clearly defined. The surface over the salt area, particularly in its western part, has long been known to contain small shallow saline lakes, which, even prior to the Civil War, were a source of salt that was hauled to points as far distant as Mexico. That the deposits, composed largely of red beds, gypsum, salt, and anhydrite, attracted the att.ention of the early explorers is shown by the report of Marcy (f); in 1852 he traced gypsum beds for 350 miles in a southwest direction from the Canadian River in Oklahoma. In 1878 Hill (8) called attention to the enormous deposits of salt and gypsum in what was then already known as the Permian Basin (although it was not fully accepted as of that age); he stated that it was once a n inland sea, the deepest part of which was not far from the southern border. Much material of scientific and economic interest concerning different parts of the area has been published since 1WZ in reports of the Geological Survey, in state reporta, and in technical literature. Two basic reports are of particular interest in outlining the Permian Basin boundaries and its characteristics. The first was published by Adams ( 1 ) in 1904 and included a description of the gypsum deposits in the Perinian Basin states. The other, published by Darton (4) in 1921, described the Permian salt deposits, and included a map showing the extent of the salt area over the several states; it was based on field work in eastern New Mexico to which he was assigned in 1913. Beginning with 1910, geologists of the Geological Survey liave studied various phases of the potash possibilities of the Permian Basin as part of the systematic search for potash in the United States, conducted by thesurvey for a generation before succefis was finally attained. The search for water, oil, gas, salt, and potash in the area led to the drilling of many holes, the sinking of shaft.$, geophysical prospecting, and surface and subsurface geological examinations, all of which have yielded much information that was not available in 1921 when Darton (4) estimated that the salt area underlaid 100,000 square miles, contained 30,000 billion tons of salt, and lay at depths that varied to more then 2000 feet below the surface. Hoots (9)reported that the Permian succession, principally red beds, salt, and anhydrite, was as much as 10,900 feet thick near the border of southeastern New Mexico. One of the eighty holes that he studied, the Means well, was in this region (Figure 3); when the well was drilled, the aggregate thickness of salts penetrated amounted to a t least 4080 fect, of which 1391 feet or more consisted of common salt. These statistics enable us to visualize inore clearly the long continued desiccation that must have taken place and the amount of salts that must have been formed by crystallization in the inland sea that served as an evaporation basin. From a chemist's standpoint, this is one of the greatest crystal crops ever harvested by nature. The source of this immense body of salts bas caused some speculation. Much of the deposit, according to general belief, came from an ocean to the south, of which the Permian Basin was a shallow, northward embayment that progressively subsided as the salts and associated sediments were deposited. The subsidence was more or less intermittent and thus permitted many alternations in the sequence of deposits. As tlie subsidence gradually deepened southward, the centers of intensive evaporation also shifted southward, so that the saline deposits in the south part of the basin are stratigraphically younger than those farther north.
The salts or brines in many inland lakes differ to some extent in character and amount from those in ocean water, and this has lent support to the conclusion that the salts in the Permian Basin were probably of oceanic origin. Tlre theory of a connectinn with the ocean is not essential; the salts irr ocean brine oxist in about the same proportion as those in some inland sess, such as Great Salt L&e, fJtah, the salinity of which (3) is, howover, several times as great as that of ocean water. Considering the magnitude of the salt deposits in the Permian Basin and the possible extent of the drainage area that may have fed an inland sea during the desiccntion period, it is natural to conclude that the ocean was the source of the greater part of the salt. Moreover, the geologic history of the basin, as described hy King, Lang, Mansfield, and other writers, points rather clearly to an oceanic origin of the salt. Tire Permian Sea was not %single,unchanging water body covering the salt basin that extended through Kansas to southern Texas. In the long period represented by Permian time, i t consisted of a succession of seas, the shore lines of which may have changed greatly and a t different times, from the beginning of deposition of the salts until the last of then1 was covered by clay and sand. Tho order of deposition was calcinin carbonate, calcium sulfate (mostly in the form of anhydrite), and then sodium chloride, with tlre potash and magnesium in the mother liqoors. From time to time, after the first anhydrite was deposited, the salinity of the water changed; in some areas only anhydrite was deposited for lnngperiods. Snme gypsum was also deposited. Many minor changes in conditions of (leposition are s h a m by the varying sequences of anhydrite, salt, and clayey material. The anhydrite a t or near the surface has been hydrated to gypsum.
Geological Formation A geologic cross section of the potash-haling beds (Figure I) and associated salts in the Kew Mexico potash field show as many as forty beds (Figure 2) that contain potash salts (I 7). These beds indicate many repetitions of periods of desiccation sufficient to concentrate brines and cause the crystallization of potash salts. However, the deposition of pothsh salts was not all due directly to desiceation but in many instances to a series of replacements after depnsition. Changes in thickness of some beds, such as anhydrite, derived from less saline brines and alternation of t.hose beds with beds of potash-bearing salts from more concentrated 855
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INDUSTRIAL AND ENGINEERING CHEMISTRY
brines indicate corresponding changes in the duration of periods when the brines had corresponding degrees of salinity. Some periods of fairly uniform conditions were relatively long, if judged by the thickness of the beds that represent them. Assuming ocean waters to have been the ultimate source of much of the salt, their inflow into the basin was interrupted many times, possibly by silting or erosion a t the places of connection with the sea or by tilting or other land movements. Early writers thought that the logical place to look for potash was in the deeper parts of the basin. However, the high-grade potash salts thus far discovered are on the western flank of the basin. Mansfield (12) described clearly how earth movements may have caused changes in surface levels and moved the mother liquors from one place to another, so that the final concentration of a given potash deposit might be a long distance from the center of the basin or from the thickest salt deposits; the mother liquor in subsidiary pools may have been cut off from the main body of brines and evaporated to crystallization locally. The present thickness of the salt, as a result of subsurface solution and surface erosion, may be much less than its original thickness. Salt masses and beds of clay described by Ageton ( 2 ) in the potash mines near Carlsbad and the numerous surface depressions over the salt deposits suggest solution and local settling of salt beds in the district. Crystallization of the salt and associated min3 UPPER erals was not controlled 4 5 by conditions of constant heat and uniform rate of evaporation. Instead , POLYHALITE 6 there were slow or even rapid changes in seasonal and daily temperatures, varying degrees of humidity, and different rates of evaporation caused by rains, winds, and arid conditions. Consequently the salts are not evenly stratified or of uniform texture. I n deep bodies I5 UPPER of water these changes I6 I7 tend to be better equalSYLVITE ized t h a n i n s h a l l o w 19 HALITE pans. 20 Final deposition, i n some stages a t least, laid down a spongelike mass of salt, with brines filling the openings ; this condition now exists a t Searles WLITC Lake, Calif. From residual brines containing LOWER 7SO potassium, magnesium, 3 1 POLYHALITE and sodium chloride, the potassium and magnesium HAL1 TC would be expected t o crystallize as carnallite 34 ZONE 35 (KCl.MgC12.6HzO) mixed with some sodium chloFIQUEE2. COMPOSITE LOG ride. No evidence of the SHOWING RELATIVEPOSIdeposition of carnallite TION OF POTASH DEPOSITS from the more complex IN PERMIANSALT BASIN brines of Searles Lake has ABOUT 20 MILESEASTOF been reported. CARLSBAD, N. MEX.
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The minerals found today in some beds appear to be such as would be deposited by evaporation of brines. I n other beds they seem to have been formed by replacement or by a succession of replacements. I n numerous instances polyhalite has replaced anhydrite or halite. In some of the areas a succession of replacement changes was noted that involved the upward growth of crystals of gypsum from layers of magnesite through successive layers of anhydrite. However, this gypsum had been completely replaced by halite that still preserved the crystal form of gypsum. More advanced stages involved the replacement of the halite by polyhalite. Schaller and Henderson (15) described these changes as well as other associations of the different minerals in the salt deposits, Twenty-four such minerals were identified. Contributing factors in this conversion of minerals may have been the pressure applied by accumulated sediments on top of the spongelike mass, which gradually closed the brine-filled openings and forced out the entrapped brines, and the subsequent reduction of this pressure with uplift and erosion of the region. Pressure due to folding and tilting of the beds and the circulation of subsurface brines may also have been factors. Even today the crystals in the sylvite-halite horizons are not entirely consolidated but contain as much as 1 per cent of fossil water. The salt masses, described by Ageton ( 2 ) , occupy from 5 to 15 per cent of the area of certain sylvite beds. Thus the failure of the drill to find sylvite in a given hole may be due to its penetration of salt in the potash bed. The variations just discussed in the conditions affecting the deposition of potash-bearing beds make it difficult or impossible to correlate deposits that are far apart and, in some places, even those that are relatively near one another. Fortunately, near the potash mines in New Mexico, a distinctive succession, comprising anhydrite, salt, and white polyhalite, has been identified that makes possible the correlation of the potash deposits over an area covering several townships, The potash beds in this area vary, however, in thickness, purity, and extent, and have few characteristics in common with those above or below. Figure 1, a cross section through the potash deposit being mined, shows the relative position of two groups of beds where sylvite is found and their relation to the top of the eroded salt deposits. Figure 2 is a composite log through the upper thirty-five potash beds on leased public lands and shows the relation of the beds in the various groups.
Search for Potash The search for potash in the Permian Salt Basin was the result of a demand for potash for plant food. Germans discovered in 1840 that potash was essential to plant growth. Potash itself was discovered in Germany in 1843 in the brine of a salt well. I n 1857 i t was found as a mineral in the course of sinking a shaft for salt. I n 1858 potash in soluble mineral form was found to be a satisfactory source of potash for plant growth, and expgrimental work soon followed for the separation of the potash from the salt. The potash salts obtained incident to shaft sinking were used in this work. The initial production from the mine amounted to 2293 tons in 1861. Mineral potash was introduced to American agriculture in 1872. In Germany these events were followed by a governmental policy that permitted overproduction of potash. This policy included the sinking of too many mine shafts, numerous acts for government price control, and, finally, cancellation in 1910 of contracts made with American agents during a free period in 1909 for potash a t a lower price than that later established. The cancellation of these contracts involved a loss to American buyers over a 7-year period of approximately $28,000,000. This action brought clearly to the attention of the world, particularly the American people, the extent of German in-
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residue. Of two fluence over our samples from food and textile Crane County in production. HowthePermian Basin, ever, the selling of one contained 2.4 potash in this grams of p o t a s country was based sium per liter or to a large extent 1.58 per cent as on convincing our potassium chloride agriculturists that in the anhydrous they would benefit residue. materially by the Of nine samples liberal use of potof n a t u r a l brine ash fertilizers. collected in KanAt the time of sas during 1910, the discovery and none analyzed as during the period much as 1 gram of of development of potassium per the German potliter. However, a ash deposits, sample from a well America was exdrilled for gas near porting to Europe Ellsworth, Kans., potash manufacwhich a n a l y z e d tured from wood but 0.1 gram of ashes. ‘ThemanuDIAMOND COREDRILLINGRIG USEDT O PROSPECT FOR POTASH ON LANDS potassium per facture of potash HELDBY THE UNITEDSTATESPOTASH COMPANY IN NEW MEXICO liter, c o n t a i n e d was America’s 4.78 per cent pomost thriving chemical industry tassium chloride in in 1850; from the Revolution to the Civil War ( I @ , with the anhydrous residue, showing a marked potash enrichment. Phalen refers to wells drilled for oil, gas, or water a t Carlsthe exception of a few years, the value of exports alone bad, east of Artesia, and a t Roswell, and to numerous wells in ranged from $500,000 to $2,000,000 a year. With the dethe staked plains of New Mexico, but no analyses are given velopment of potash mines in Germany and the introduction of these waters or of the anhydrous salts. In 1912 the search of mineral potash to world markets, exports of American led to the sa,lt lake southeast of Carlsbad now used for the potash ceased and production dwindled. Samples of brine from Colorado, Idaho, Nevada, and Calidisposal of waste salt from a potash refinery. The brine contained 11.15 per cent of dissolved salts, 0.85 per cent of fornia were collected by members of the 40th Parallel Survey (10) and other early expeditions made after the Civil War, which was potash. Hance (7) stated that the dissolved maand were analyzed for potash. Many samples of water and terial was evidently leached from the adjacent rocks which rocks were also collected subsequently by members of the belong to the red beds. This lake is one of many shallow Geological Survey and analyzed. An analysis of one such pools in the salt area. sample of salt collected in the Permian Basin in 1904 (14) I n 1912 Gale (6) wrote that the agitation over potash spread the interest in American potash deposits throughout from a salt flat 15 miles southwest of E l Capitan Peak, in the country in a way almost unprecedented in the history of western Texas, showed 2.28 per cent of potassium chloride. Mention is also made of potash (6) occurring in the artesian the nonmetallic mineral products. Although the interest of waters of the Roswell area. the public in the finding of a domestic supply of potash was I n 1910, the year the contracts for potash were finally only awakening, the hope that a n independent supply of cancelled, the Geological Survey and the Bureau of Soils copotash might be found in the Permian Basin of Texas and operated in an intense search for a domestic source of potash. New Mexico had long been held by geologists. Attention Those engaged in drilling for oil, those producing salt, and had been called in 1910 to the red beds in Texas, Colorado, and others, were solicited by the survey to submit samples for New Mexico, and the suggestion was made that they might analyses. The analyses from 1910 to 1912 were, for the most profitably be explored where structural conditions seemed to part, made by the Bureau of Soils, under the direction of Turfavor accumulation and retention of the salines. rentine. Later a potash laboratory was established by the I n 1911 and 1912 much exploratory work was done outside Geological Survey a t the Mackay School of Mines, Reno, the Permian Basin, and publicity was given to a number of Nev. Hundreds of samples of brines, bitterns, rock salt, and potash discoveries, including those in western Nebraska, rocks collected by government and state agencies or sent in western Utah, and at Searles Lake, Calif.; all three of these by drillers and prospectors were analyzed. Analyses made deposits beca,meimportant sources of potash during the World in 1910 and 1911 of forty such samples of natural brines from War. The announcements of a discovery in a deep well drilled Texas, Oklahoma, and Kansas are listed by Phalen (14) and for water at, Spurr, east of Lubbock, in Dickens County, Turrentihe (21). Twenty-six of these samples were collected Texas, received wide publicity because of the investigator’s in Oklahoma, and of the seven that analyzed one gram or more belief that the water came from a bed of potash salts. per liter in potassium, three were collected in the Permian I n December, 1912, Udden (22) gave the potash content of Basin area. Potassium sulfate was also reported from the the water of the Spurr well and sixteen other wells drilled for middle of the three plains in the Permian area of Jackson water. With reference to the Spurr well he stated that the County, Okla. presence of much anhydrite and salt in the upper 1200 feet Of five samples of natural brines collected in Texas in 1910, of the section caused him to suggest that analyses of the two from Hardin County in the southeastern part of the water be made for potash. I n April, 1912, a sample of water state contained 3.4 and 3.2 grams of potassium per liter, or that had been standing in the well for 2 months was obtained 3.56 and 8.48 per cent as potassium chloride in the anhydrous a t a depth of 2200 feet, after the water had been lowered
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INDUSTRIAL AND ENGINEERING CHEMISTRY
to that point. The analysis of this water showed 5 grams of potassium chloride per liter and 5.4 per cent of solids. Five grams of potassium chloride per liter are equivalent to 2.6 grams of potassium or 0.26 per cent of potassium. For comparison, twenty-four of the forty natural brine samples previously referred to from Kansas, Texas, and Oklahoma, analyzed in 1910 and 1911, contained as much as 1 gram of potassium per liter. However, the relative amount of potash and sodium in the anhydrous salt from this well indicated more potash enrichment. Fourteen additional samples were taken from the Spurr well in June, 1912, and analyzed. None of these fourteen samples contained as much as one-tenth the amount of potassium chloride in the total solids as was found in the April sample; the only one that contained as much as one-third the amount of potassium chloride in the brine was taken from the same depth as the April sample. Udden (23) stated in 1914 that his attention had been called to a deep boring for water; he visited the location to secure a log of the well, examine some pieces of core, and to arrange to procure specimens and samples of the material penetrated. Twenty-three sections of the well, all between the depths of 913 and 2264 feet, had been cored. With the assistance of the Geological Survey, three hundred and thirty samples of cuttings and pieces of core were examined. Thin sections were made of some two hundred rock samples. Nearly all the rock examined was dolomite, limestone, or anhydrite. KO potash was found, except a trace a t a depth of 2047 feet, and a pronounced trace a t 2110 feet. The flow of water filled about 160 feet of the hole overnight, indicating a flow of about one barrel per hour. The well was drilled with a rotary machine to a depth of 4489 feet, a t that time the deepest exploration in the state. The amount of potash found in the Spurr well was not significant in itself. One wonders why such wide publicity was given to the claimed discovery of potash in such a small flow of weak brine from a horizon primarily dolomite and more than 1000 feet below any definite occurrence of salt, when no potash mineral could be found during the course of such careful examination of the rock specimens. However, the wide publicity given this particular hole by state and federal agencies did stimulate the search for potash. Possibly the conclusion that the potash must originate in a potash-bearing horizon and the fact that attention was drawn to the resemblance of the stratigraphy to that of the Stassfurt deposits in Germany contributed much more to this interest than did the potash content. The result was that many began to look out for evidences of potash, including drillers in whom reliance was often placed for the securing and proper labeling of cuttings. Udden (83) continued the search enthusiastically and in 1914 published the details of his investigation on the Spurr well, In 1915 he gave the results (24) of his investigation of the drill logs and cuttings from fifteen other wells, three of which, the Boden, Miller, and Adrian wells, in Potter, Randall, and Oldham Counties, respectively, were in a triangle west of Amarillo. Many samples were analyzed (24). I n some instances only 2 or 3 grams of the salmon-red salt appear to have been found in about 200 pounds of cuttings (9). The Boden well, drilled 23 miles northwest of Amarillo, was completed in September, 1914. From a sample of cuttings obtained between the depths of 875 and 925 feet, small fragments of a salmon-red salt were picked out which analyzed 9.23 per cent potash and contained little inso1;ble material. This was the first definite discovery of soluble potash in mineral form from well cuttings. The Miller well, 18 miles southwest of Amarillo, was finished in February, 1914. Cuttings obtained between depths of 1500 and 1700 feet included some salt that contained
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6.14 per cent potash. Another sample, from a depth below 1700 feet, consisted of a fragment of compact anhydrite t h a t contained embedded, irregular salt crystals that analyzed 10.50 per cent potash. After these analyses were made, the salt on the dump a t each of the wells was searched for similar substances; several samples were analyzed but the potash content of each was low. The Adrian well in Oldham County (completed in 1911) was visited, and only one bottle of cuttings was found. These cuttings represented different strata. The one small piece of red salt observed in the cuttings was believed to be potash salt. The quantity of red salt obtained from the three wells was not considered sufficient for mineralogical determinations, but Udden suggested that the salt was a real potash mineral, such as carnallite or polyhalite. Although many samples from the other twelve wells were examined, no potash was reported. The fifteen wells covered examinations in eleven counties. On the basis of the occurrences of potash in the Boden and Miller wells, representatives of Texas and of the Geological Survey concluded that the most promising location for an exploratory boring for potash was near Amarillo; a site about 8 miles northwest of Amarillo was then selected. The funds available to the Geological Survey for drilling were limited, and a churn drill hole was started in December, 1915. Drilling was stopped in February, 1916, owing to lack of funds, and t h e hole discontinued in October, 1917, at a depth of 1703 feet. This experiment was made under the supervision of N. H. Darton of the Geological Survey. I n the meantime, on t h e basis of the reported discovery of potash in the Vineyard water well, southeast of Carlsbad, N. Mex., Longyear had started and completed a core test nearby. Neither of these borings disclosed potash in any encouraging amount. The failure of these two wells, drilled especially to prospect for potash, did not weaken the belief that potash deposits rivaling those in Germany would eventually be found in some areas where residual brines containing potash were finally evaporated t o crystallization. The various state, government, and private agencies continued to cooperate in the search for such a deposit.
Discovery of Potash in the Basin Not until February 17, 1921, was any potash mineral from the Permian Salt Basin identified. The first specimen was polyhalite, a salmon to red salt, collected between the depths of 2405 and 2426 feet from the Bryant well which was drilled 9 miles south of Midland, Texas. This well is much farther south than the Amarillo discoveries. Analyses of a few of t h e cleaner specks of polyhalite showed 15.63 per cent, the potash content of pure polyhalite. Polyhblite was identified soon after by the Geological Survey in cuttings from the Pitts well, in Ward County; from the Burns well, in Dawson County; the Means well, in Loving County; the Jones well, in Borden County; and the McDowel1 well, in Glasscock County (25). From the Pitts well, where four potash horizons were noted between 1405 and 1704 feet, the highest percentage of potash in soluble salts (14.40 per cent) was contained in cuttings obtained between 1600 and 1610 feet. Two specimens were found in cuttings obtained between 1000 and 1500 feet; they were found to be practically pure polyhalite. A selected sample obtained between 1070 and 1075 feet in the Jones or Long well, in Borden County, analyzed 22.9 per cent potash in the soluble sdts, also very close to the theoretical content of pure polyhalite; a sample obtained between 1075 and 1083 feet analyzed 17.68 per cent; and a sample a t 1115 feet analyzed 6.56 per cent. Seven potash zones were found in the McDowell well.
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FIGCRE 3. SOUTHERN ENDOF PERMIAX BASININ NEWMEXICO AND TEXAS The location is shown of Longyear well, the first core test made for potash in'the Permian Basin; Bryant well from which the first polyhalite i n the Permian Basin was identified in 1921; M c N u t t well where sylvite was first discovered in the Permian Basin in 1925; Means well, drilled in 1921 near t h e thickest part of the salt series; the Standard Potash Company and Eldridge core tests m Texas; and government potash core tests 1 t o 23, drilled in 1926-1931.
\
T h e Means well was bailed each 5 feet, and samples were obtained for analyses. This was the first well from which complete cuttings became available for examination. Potash was found a t twelve or more horizons, a thickness of several feet being indicated in some instances. Core drilling near the Means well was recommended and later undertaken by private interests. T h e total thickness of salt in the Means well was 1391 feet, as compared with 700 feet in the Adrian well, the thickest salt previously reported. Hoots (9) gives the potash analyses of cuttings in relation to depths graphically for ten wells. The graph for the Burns well shows two beds, each of which contains an unusually high percentage of potash. A sample from one of the beds, taken a t a depth of 1780 feet, analyzed 11.45 per cent potash in the sample and 21.10 per cent potash in the soluble salts; a sample from the other bed, taken a t a depth of about 1900 feet, analyzed more than 15 per cent potash in the sample. It was early recognized that the value of a discovery could not be determined by the examination of cuttings, although information so obtained might determine locations favorable for core drilling. Well cuttings furnish but a blurred picture of the formations penetrated (IS), especially of those drilled with a rotary machine and with mud as the drilling fluid. Fragments of the various strata penetrated become mixed, with the result that some are recorded as being a t a much greater depth than they actually are. When fresh water is added, particularly in churn drilling, much, and a t times all, of the soluble minerals, such as salt, sylvite, and carnallite,
may be dissolved unless a sufficient amount of the salts is present to saturate the solution. Identification of potash in cuttings was made for some years by a combination of chemical and microscopic tests. In the instance of the Spurr well, as many as two hundred thin sections were made. The conclusion was reached, however, about the time government drilling got under way, that the most complete and reliable examination of cuttings could be made by examining them in finely powdered form with a petrographic microscope, using immersion oils with known indices of refraction. The wide use of this method by F. C. Calkins of the Geological Survey contributed much to t h e finding of potash minerals in cuttings. Over a period of years those engaged in exploratory work advocated securing an appropriation from Congress for prospect drilling. Finally a bill was passed that provided for an appropriation of $500,000 to be spent for prospecting in equal annual amounts over a period of 5 years by the Geological Survey and the Bureau of Mines. The bill was approved in June, 1926, and late in July the first government core test was started.
Commercial Developments In August, 1925, the writer was informed of a rumored discovery in the V. H. McNutt oil test well drilled by t h e Snowden & McSweeney Company on government lands east of Carlsbad, N. Mex.; samples of the cuttings were supplied that had been carefully selected by the company a t intervals
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INDUSTRIAL AND ENGINEERING CHEMISTRY
of 5 to 10 feet. When these samples were examined microscopically and were found to contain unusual amounts of polyhalite (20) and also the mineral sylvite, the quantity of sylvite was small, but its occurrence was considered very important. This was the first time that either sylvite or polyhalite was identified from New Mexico sources, although the officials of the company had found potash salt prior to August I, 1925. According to McNutt (11) the well penetrated such thick salt and contained so much pink material answering the description of the mineral polyhalite that numerous samples were analyzed. However, on August 6, 1925, 4 days before the report on the first analyses were completed, a n application for a prospecting permit was filed by McNutt. He was convinced that a n important discovery of potash had been made. McNutt was advised by the survey of the discovery of sylvite in the cuttings from his well, even though the analysis showed but 3.48 per cent potash in the soluble salts as compared with as much as 14.97 per cent potash in one of the several polyhalite beds. He appraised the importance of sylvite, with its equivalent, when pure, of 63.2 per cent potassium oxide, whereas pure polyhalite has only 15.6 per cent potassium oxide. The Snowden & McSweeney Company then became interested in core drilling for potash. This core test was started April 14, 1926, about 500 feet from the discovery well, and revealed a deposit of sylvite equal in purity to many of the potash deposits being mined abroad. In July the Federal Government began prospect core drilling in New Mexico, and soon afterwards the Gypsy Oil Company began the first of its series of four core tests. In July, 1925, the Standard Potash Company began drilling for potash in Midland County, Texas. Two wells about 2.5 miles apart were drilled, and the cores were analyzed by Sellards and Schock (18). A press announcement (June, 1926) was the first public record based on diamond drill cores to show the thickness of potash beds in the Permian Basin. A 5-foot bed of polyhalite was reported to have been discovered in the first hole a t a depth of 2075 feet, and in the second hole, beds of minable thickness were found a t 1980 and 2172 feet. Ninety-seven core tests have been drilled for potash in the Permian Basin-seventy-four by private interests (three in Texas and seventy-one in New Mexico) and twenty-three by the Government. No less than twenty-four different minerals have been found in cores or cuttings from the various holes bored into the formations. The potash minerals in the order of their identisylfication are: Polyhalite (2CaSO~.MgS04~K2SO4.2H20), vite (KCl), kainit (MgSO4.KC1.3HzO), carnallite (MgC12.KC1.6HzO), langbeinite (2MgS04.K2S04), leonite (MgSOdK,S04.4HzO), and aphthitalite or glaserite [(K,Na)2S04]. The principal nonpotash minerals are halite (NaCl), anhydrite (CaS04), gypsum (CaSO4.2H20),and kieserite (MgS04.H20). The holes drilled by the Government extended over a wide area and were a t some distance from the relatively small area where any drilling was being done by private interests; for example, test 9 (Figure 3) is about 180 miles from test 1. A detailed description of the discoveries in each of the government wells was given by Mansfield and Lang (IS). Figure 3 was compiled from their publications, which indicates the boundaries of the southern end of the Permian Salt Basin, the location of government core tests, and related information (18). The occurrences of potash in some of the seventyone core tests drilled in New Mexico revealed four areas of particularly great economic and national importance; these areas, together with public lands having prospective value for potash, have been placed under potash withdrawal to prevent alienation of the mineral title under the nonmineral laws. One of the areas was discovered by the Geological Survey and three by private drilling. Two of the latter
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have been developed, and the third is in the course of development. Polyhalite has been found in minute quantities as far north as Trego and Stafford Counties, Kans. Polyhalite has also been found in small quantities west of Amarillo, Texas, and further south it is commonly identified in oil well cuttings. The area in which polyhalite has been found constitutes approximately 40,000 square miles (IW), where approximately one core test has been drilled for each 400 square miles. Most of the core tests, however, are within a small area in New Mexico, near the mines of the two operating companies, the United States Potash Company and the Potash Company of America. The area in which the most soluble potash minerals (sylvite, carnallite, and langbeinite) are found constitutes about 3000 square miles, nearly all in New Mexico, in which eighty core tests have been drilled. The part in which as much as 14 per cent potash has been found in beds 4 feet or more in thickness, covers about 35 square miles, and one hole has been drilled for approximately each square mile in that area. The four known potash areas extend 17 miles north and south, and the boundaries have been reasonably well defined along the western erosion line where the potash horizons are in proximity to the top of the salt beds. The north, south, and east boundaries, however, have not been accurately determined. The potash content of the four areas mentioned is higher than the average potash content of salts in the mines of either Germany, France, Poland, Spain, or Russia. The reserves, based on a minimum of 14 per cent potash in beds 4 feet or more in thickness, were estimated by the writer in 1933 to be in excess of 100 million tons of potash salt. This reserve will be materially increased as the mines are extended and more prospect holes are drilled.
Acknowledgment The writer is indebted to G. R. Mansfield, N. H. Darton, and R. K. Bailey for reviewing this paper. Darton and Bailey ‘were connected with this work as early as 1912, and since 1918 Mansfield has been the active head of the potash investigation work for the Geological Survey.
Literature Cited Adams, G. I., et al., U. S . Geol. Survey, Bull. 223 (1904). Ageton, R. V., Am. Inst. Mining Met. Engrs., Tech. Pub. 686 (Feb., 1936). Clarke, F. W., U. S. Geol. Survey, Bull. 770 (1924). Darton, N. H., Ibid., 715 (1921). Fisher, C. A., U. S. Geol. Survey, Water Supply and Irrigation Paper 158 (1906). Gale, H. S., Am. Fertilizer, July 27, 1912. Hance, J. A., U. S. Geol. Survey, Bull. 540-P (1913). Hill, R. T., Ibid., 45 (1878). Hoots, H.W., Ibid., 780-B (1925). King, Clarence, Rept. Geol. Exploration of 40th Parallel; Professional Papers Eng. Dept., U. s. A., No. 18; Vol. 2 , Descriptive Geology, 1877. McNutt, V. H., Oil Gas J., March 27, 1927. Mansfield, G. R., and Lang, W. B., Am. Inst. Mining Met. Engrs., Tech. Pub. 212 (1929). Mansfield, G. R., and Lang, W. B., Univ. Teras Bull. 3401 (1934) ; Separate, 1935. Phalen, W. C., U. S. Geol. Survey, Bull. 669 (1919). Schaller, W.T., and Henderson, E. P., Ibid.,833 (1932). Sellards, E. H., and Schock, E. P.,Univ. Teras Bull. 2801 (1928). Smith, H.I., Am. Inst. Mining Met. Engrs., Contrib. 52 (1933). Smith, H.I., chapter on ‘‘Potash” in “Industrial Minerals and Rocks,” pub. by Am. Inst. Mining & Met. Engrs., 1937. Smith, H. I., Eng. M i n i n g J.,Dee., 1933. Smith, H. I., Oil, Paint, Drug Reptr., June 29, 1931. Turrentine, J. W., U. S. Dept. Agr., Bur. Soils, Bull. 94 (1913). Udden, J. A,, Am. Fertilizer, Dec., 1912. Udden. J. A., Univ. Texas Bull. 363,Sci. series 28 (1914). Ib%d.,17 (1915). White, D., M i n i n g and M e t . (April, 1922). RH~CEIVED May 9, 1938. Published by permission of -the Director, U. 9. Geological Survey.
