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By R. W. Hodder

"Archean lode gold deposits of both vein and chemical sedimentary types typically have major enrichments of certain rare elements, including Au, Ag, As, Sb, B, W, Se, Te and Bi, coupled with low or negative enrichments of the more abundant and mobile base metals, Cu, Pb and Zn. On the other hand, in massive base metal sulphide deposits Au, Ag, Cu, Zn and in some instances Pb are all enriched by a factor of 200 to 2000 t:'Jf'1pared to background and there is no large separation of gold relative to the base metals.The fluids from which gold was precipitated in veins were at temperatures of 320 to 480°C, at lithostatic pressure, had significant C02, and Na """" K; whereas the fluids which generated base metal deposits were at 250-300°C, at hydrostatic pressure, had C02 < < H20 and Na > > K.Many lode gold deposits are characterized by K, C02 and Si additions to their enveloping rocks, whereas base metal deposits typically have a fixation of Fe, Mg, Si and S in footwall rocks. Lode gold deposits may also have a relatively large halo of low-temperature oxidative, sadie spilitization in enclosing volcanic rocks, where seawater has later streamed into cooling stocks or flows that have initially acted to focus gold mineralizing fluids along thermal contraction fractures. The submarine environment is one hydrologically appropriate for the mixing of two initially independent hydrothermal systems, and the blending of their separate characteristics. Hence, lode gold and base metal massive sulphide deposits appear to be products of two distinctly different crustal and hydrological regimes. The former involves a high-temperature, high-pressure discharge of fluids which probably were generated during dehydration accompanying burial and progressive accumulation of volcanic-sedimentary sequences, with an additional influence of marine water in the near-sea-floor environment. The latter represents thermally driven convection of ocean water at lower temperatures and under hydrostatic conditions.Auriferous fluid systems with only minor base metal content could plausibly be generated during dehydration accompanying burial and metamorphism, when the water-to-rock ratio is low and halogen availability is limited by crustal abundance (- 60 ppm Cl). These two factors may constrain the uptake of the abundant base metals into fluids, but the solubility of rare elements is not constrained by limited fluid; and preferential uptake of Au along with other rare elements may be promoted if such elements compete more successfully for the limited halogens than the base metals, and/or have an alternative complexing agent such as CO or C()j-."

Jan 1, 1982

By Joachim Ulrich

The spreading and splashing behaviour of single tin, lead, copper, aluminium and steel droplets impacting on a solid surface were experimentally examined. The droplet impact was observed using a high speed video imaging technique. The onset of splashing and the mass of the secondary droplets of impacting tin and lead droplets was quantified by the weight difference of the droplets before melting and the splat after the impact. The spread factor and the mass of the secondary droplets in dependence of the impact velocity is shown for different droplet materials, initial droplet diameters, target temperatures in ambient air and inert gas atmosphere. An empirical found correlation predicting the transition from spreading to splashing is presented by means of dimensionless numbers.

Jan 1, 1999

By P. Reyes

The start up and operational optimization of the No. 3 Oxygen Plant at the Caletones Copper Smelter of the Codelco - Chile El Teniente Division is summarized. In addition, the economic impact of such optimization on the production cost of oxygen and others aspects associated to the operational robustness as well is detailed.

Jan 1, 2007

By Craig J. Brown

Despite its great potential utility, ion exchange has only achieved limited application in hydrometallurgy. To a significant extent this is due to the limitations of conventional ion exchange process design as well as the properties of the ion exchange resins themselves. Over the past decade several new ion exchange resins have been introduced with properties that make them potentially very useful for various hydrometallurgical separations. In addition, a novel ion exchange process called Reciprocating Flow Ion Exchange or Recoflo, which has been employed in the metal finishing industry for the last dozen or so years for chemical recovery and effluent treatment, has been shown to offer a number of unique and significant advantages over conventional I.X. technology.

Jan 1, 1984

By T. T. Toomver

The evolution of Inco&apos;s Selective Reduction Smelting Process as practised today is described, beginning with the initial laboratory experiments on small samples to the processing of large bulk samples through pilot plant equipment. For both the Guatemalan and Indonesian (Soroako) ores, the initial screening tests using hydro-, vapo-, and pyro-metallurgical processes showed that the latter was the most promising both metallurgically and economically. Later, larger scale tests confirmed the earlier testwork.

Jan 1, 1979

By S. I. Freedman

Coal-oil mixture (COM) combustion technology is regarded by the Department of Energy as near term, and potentially applicable to existing utility and industrial steam generators and for injection into blast furnaces. From work done previously, it has been established that COM can be burned in existing boilers, into blast furnaces. Therefore, the issues being addressed by the current DOE program are: (1) determination of best available technology to achieve environmentally-acceptable long-term reliable operation and (2) determination of applications for which COM can be utilized economically. Some of the technological options have begun to be determined by projects already under way. However, many projects are still in the early stages of development.

Jan 1, 1978

By W. J. Douglas

Before discussing minicomputer software for the mineral industry, it is helpful to explain some of the computer program terminology. Most of the terms are the same as those applied to large computers. A computer system consists of a machine (hardware) with electronic and mechanical components and instructions (software) that define its operational logic and sequence. This logic is described by sets of commands grouped into programs. Each program has specific objectives related to the computer&apos;s operation and to production information from computer data that are input and processed. Software, therefore, is a general term applied to any type of computer program. Instructions to the computer are communicated through languages that convert logical and arithmetic statements into machine operations. The languages may consist of statements resembling mathematical or logical phrases understandable by humans, or they may be coded statements with no apparent resemblance to spoken language but readily understandable by the computer. Computers also translate higher level languages such as FORTRAN or COBOL into machine languages using other programs called Compilers. Programs written in these higher level languages are generally called source code. However, programs written in computer assembly language may also be called source code. The compiled version of the program after it has been translated by the compiler software is called object code. Programs used to "instruct computers how to be computers" are generally called systems software. They relate more to computer operation than to producing externally usable results. Programs producing information for many users-engineers, accountants, managers-are termed applications software. For the most part, applications software is the principal concern of the mineral industry. Programs are developed to fit user requirements as interpreted by programmers. Programs vary in quality, precision, efficiency, accuracy, and complexity, depending on programmer skills and abilities and programming decisions forcing design tradeoffs. A well written program should have speed, efficient use of available hardware resources, accuracy, and an inherently logical structure that aids documentation and subsequent modifications. Programs developed to fit specific requirements are termed customized software. A program organized and prepared for general commercial use is called a package, or a software package, and includes documentation for program use. A form of customized software that takes an existing program or package as its starting point and modifies it is called a customized package. A minicomputer program can be stored on computer cards, standard magnetic tape, magnetic cassette tape, floppy disk, or hard disk. The software purchaser or lessee may select one or more of these media when specifying a program in a software contract. Supporting documentation may include a listing of the program instructions linkages, hardware and storage resource requiremnents, flow charts, and programmer and user manuals. The purchaser must carefully make and clearly understand specifications for media and format of program delivery. This assures that delivered software is compatible with the intended hardware. Mineral Industry Attitudes Toward Computer Software The mining industry has traditionally been conservative concerning computer applications. Furthermore, large computer costs have made these systems accessible only to large companies, for the most part. But in the past few years, mining software systems developed at schools such as Pennsylvania State University and Virginia Polytechnic Institute have gained wider acceptance in the mineral industry. More mining engineers now have academic training in computer application, and computer use is now more acceptable to the mining industry. Mining managers in decisionmaking positions are faced with a new generation of computer technology resulting from the rapid evolution of minicomputers. Not too long ago, manufacturers such as Digital Equipment Corp., Data General, and Hewlett-Packard were considered newcomers. They are now established companies. In addition, Apple, Radio Shack, Commodore, and others have emerged in the growing microcomputer industry. So the mine manager or mining executive now has more options. Mining Software is Limited Along with the rapid evolution in hardware development, much general purpose software is now being developed for minicomputers. The 1981 Apple Software Directory can be obtained for about $14; Radio Shack published the Application Software Source Book in three volumes for $1.95 each. Brochures describing software can be obtained for other minicomputer manufacturers by contacting local sales representatives. Hewlett-Packard software can be obtained and exchanged through HP user&apos;s groups. Manufacturers&apos; programming staffs are generally concerned with developing applications software. In some instances, manufacturers will recommend software developed by their hardware users. Until now, however, software development for mining applications has been minimal. This should not be surprising, since software development traditionally lags hardware development by several years. A review of A Directory of Computer Software Applications/Mini-Computers and Micro-Computers, August 1977-1980, published by the US Department of Congress, National Technical Information Service, contains many entries and subject areas. General applications include some references to tunneling machines, but there are virtually no entries specifically relating to

Jan 11, 1981

By K. KAKLIS, O. SAUBI, Z. Agioutantis, R. JAMISOLA

Machine learning in the form of artificial neural networks was applied to investigate whether specimen load evolution can be predicted as a function of acoustic emission (AE) signals in the case of three-point bending (TPB) marble specimens instrumented with piezoelectric sensors. The ultimate objective of this study is to develop a model that can quantify rock behavior under loading that can lead to rock-failure prediction in underground structures subjected to bending, such as roof failure in development or production openings.

Nov 1, 2022

By L. C. IlsLey

In January, 1922, a conference relative to trailing cables for use with permissible mining machines was held at the Pittsburgh Experiment Station of the U. S. Bureau of Mines. At this conference it was recommended that the bureau take steps to investigate the rubber-sheathed type of cables and to bring about the establishment of a list of approved cables. Effective until such time as a complete investigation could be made, the bureau asked the several manufacturers holding approvals for mining machines to recommend cables for use with their machines. In general the cables recommended were tentatively approved. Due to the lack of available personnel, no actual tests of cables were made until mid-1927. Meanwhile a field investigation of trailing cables was made at 20 mines of three coal companies in western Pennsylvania, and samples of cables were obtained from the manufacturers for laboratory tests. Twenty-five samples of the concentric-type cable, representing the product of five manufacturers, were obtained for the tests. These cables were of four sizes, as follows: 3 cables of No. 2 B & S gage, 17 cables of No. 3 B & S gage, 3 cables of No. 4 B & S gage, and 2 cables of No. 6 B & S gage.

Jan 1, 1929

By Richard R. Marston, Scott Herr, Steve Pries, Donald L. Jr Ewart

The purpose of this paper is to identify and examine alternative methods (other than shovel/truck stripping) of effecting the pre-stripping of consolidated overburden, in conjunction with dragline stripping operations, at surface coal mines. The analysis will be case study oriented with practical mining considerations and comparative economics being evaluated. Alternatives that will be examined include blast casting, dozer push, and multiple pass dragline sequences.

Jan 1, 1992

By T. L. Joseph

The purpose of this article is to describe briefly the operation of a 6-ton blast furnace on a charge of bauxite, limestone, iron ore, and cast-iron turnings and to point out the bearing which smelting such a charge has upon the production of alumina cement. One object of the experiment, conducted by the Bureau of Mines in cooperation with the Aluminum Co. of America, was to determine whether tae so-called Pedersen process3 can be applied to the blast furnace. This process consists of smelting a charge of bauxite, iron ore, and. limestone, and results in to products. One is a slag containing about 50 per cent of A1203 and is intended for use in manufacturing aluminum, and the other is iron low in sulphur. Complete details of the test are published in other reports4. Blast-furnace slag is now recognized as a satisfactory and economical raw material for making Portland cement, Wm. A. Forbes5 has recently reported that in 1926 an important steel interest used well over 1 million tons of slag in producing about 24 million long, tons of cement. This is equivalent to about ½ ton of slag for each ton of cement. Alumina cement can be made direct in the blast furnace. Its physical character would have to be changed by grinding, but no change in its chemical composition would be necessary.

Jan 1, 1928

In 2005, a total of 7,111 sand and gravel mining operations reported employment to the Mine Safety and Health Administration (MSHA). ? Sand and gravel mines were the largest mining sector, comprising 48.5% of all mining operations. ? Sand and gravel mines were found throughout all 50 states and Puerto Rico.

Sep 1, 2008

By G. M. Clarke

Minerals are certainly where they are found. The undemocratic distribution of the world&apos;s mineral wealth has created an incongruous inbalance: mineral-rich, scarcely populated countries supply highly-populated industrialised countries that in turn consume more minerals than they produce. This has been as much a generating force for colonisation, invasion, and war as religion, political ideals, or megalomania. The Industrial Revolution of the seventeenth century was born in Britain, a country with large domestic resources of coal, iron, lead, zinc, copper, tin, etc., as well as a large population. As consumption outstripped production imports filled the gap, particularly from its worldwide colonies. For example, when Canada was founded in 1867 more than 905 of its investments were British financed, and much of these were mineral-based. The British made similar investments in South East Asia, Australasia, the Caribbean, and elsewhere, as did the other industrialised Western European countries hungry for raw materials. Later the United States emerged as a leading industrial power, again due largely to its abundant natural resources. Consumption soon exceeded production and foreign sources were saught. American business went exploring abroad ant many a mineral resource was developed almost totally on the basis of the US market many .thousands of miles away. Closer to home, Canada was also an obvious target for the US with its rich mineral resource base, small population, and geographical juxtaposition, so much so that about the time of the 1914-18 War the US took over from Britain as the major investor in Canada, and this peaked in 1967 when the US accounted for 80% of the country&apos;s foreign investment. After the 1939-45 War Japan joined the ranks of the USA and Western Europe as industrialised powers, and they too searched the world for the deposits lacking in their homeland.

Jan 1, 1981

By W. L. Fink, H. C. Stumpf, L. A. Willey

VERY few studies of the aluminum-sodium system have been reported. Heycock and Neville1 were unable to detect any solubility of sodium in liquid aluminum. Mathewson2 prepared an equilibrium diagram consisting of two horizontal lines at the melting points of the two metals. He was unable to detect solubility at either end of the system. Scheuer3 first developed a method for the chemical determination of sodium in aluminum and then studied the solubility of sodium in liquid aluminum. His method involved heating aluminum with excess sodium under hydrogen until the two liquids were at equilibrium, chilling the melt, and analyzing the aluminum-rich layer. He reported the solubility to be 0.l0 pct sodium at 700°C, 0.115 pct at 750°C, and 0.128 pct at 800°C. This paper on the aluminum-sodium system is the twenty-first in a series from the Aluminum Research Laboratories describing equilibrium relations in aluminum alloy systems. MATERIALS The alloys for this investigation were prepared from electrolytically refined aluminum (99.99 pct) and sodium of reagent quality conforming to specifications of the American Chemical Society.4 Chemical analysis of the aluminum showed the following impurities: 0.002 pct Si, 0.002 pct Fe, 0.002 pct Cu, <0.001 pct Mn, 0.002 pct Mg and 0.001 pct Na. The sodium content of all alloys was determined by either chemical or spectrographic standard procedures5 No. IIA and No. SII respectively. DETERMINATION OF LIQUIDUS The boundary of the miscibility gap was determined by a modification of the method of Scheuer3 and of that used by Henry and Cordiano.6 As finally developed the method was as follows: A fused alumina crucible 25 mm id with 75 mm depth and 1.5 mm wall thickness was placed on the bottom of a container made from a 4-in. length of 1 ½ -in. iron pipe and pipe caps. The space around the sides of the crucible was filled with 40 mesh crystalline alundum. A charge of 60 g of aluminum and 10 to 15 g of sodium was placed in the crucible, the sodium first being trimmed and rinsed with iso-pentane to remove kerosene. The container was tightly capped, filled with argon (99.6 pct pure), and heated to the desired temperature (between 670 and 800°C). A positive pressure of argon (about 8 mm of mercury) was maintained through a small pipe to the upper cap. After soaking for from 2 to 5 hr, the container was quenched by directing a stream of water onto the base, so that solidification of the aluminum-rich layer was rapid and essentially unidirectional. Analyses were made on drillings taken from the bottom of the ingots after machining off the surface layers. Pre-

Jan 1, 1948

By S. A. Lever, R. Hultgren

The solidus is usually the least satisfactorily determined portion of a phase diagram. Cooling curves, which succeed well with the liquidus, show the solidus inaccurately or not at all because of segregation which occurs during freezing. Heating curves of carefully homogenized alloys might be expected to indicate accurately the solidus, but they are seldom used. Dynamic methods involving heating or cooling are never completely satisfactory because of uncertainty as to whether equilibrium is attained. A static method in which the specimen may be allowed hours, days, or even weeks to attain equilibrium is to be preferred. In a static method a solid solution, for example, is first made thoroughly homogeneous, then heated to successively higher temperatures. After sufficient time at each temperature to assure equilibrium, some property is measured which should alter strikingly when melting begins. Microscopic examination can be used to detect the beginning of melting, but the method is tedious since the specimen must be quenched, sectioned, polished, and etched before each examination. Of all the physical properties which change on melting, electrical resistance is probably the most satisfactory to measure. The measurement may be made while the specimen is at temperature without damage to the specimen. It may be repeated indefinitely to ascertain when equilibrium has been achieved. Measurements may be made on a single specimen over the whole range of temperature. Most metals approximately double their resistance on melting. Since an accuracy of a few tenths of a percent is easy to achieve, the method is highly sensitive to the beginning of melting. In spite of these advantages, which have been perceived for a long time,l,2 a reasonable search of the literature has failed to reveal a single case in which the method has been satisfactorily applied in practice to the determination of solidus temperatures. The use of electrical resistance measurements appears to have been confined in practice to changes in the solid state. In the work described in the following pages we have applied the electrical resistance method to the solidus of the lead-tin system. We have found the method to be convenient, reproducible, and highly sensitive. We chose the lead-tin system because it leads to few technical difficulties. Furthermore, a number of determinations of solidus have been made in this system by various methods and results could be checked against them. However, all published results are not in good agreement with one another, so this work should help in determining the solidus more precisely. The Lead-tin Diagram Because of its commercial importance, there have been numerous investigations of the lead-tin diagram. The results of the most recent work on the solidus are indicated in Fig 7, as well as the results of the present work. The works of Honda and Abe3 and of Stockdale4 agree fairly well with each other and with the present work. Jeffery&apos;s5 data indicate the solidus to be about 50°C lower. Honda and Abe3 used differential thermal analysis on both heating and cooling cycles. Stockdale4 used the microscopic method and also differential heating curves. Stockdale&apos;s results were about 4" higher than those of Honda and Abe at low tin contents and lower at higher tin contents. These results also agree with those of Rosen-hain and Tucker.= Jeffery5 used electrical resistance measurements of the alloy as it was being heated or cooled. Apparently he did not attain equilibrium as his results are about 40°C lower than those of Stockdale4 or Honda and Abe.3 MATERIALS AND METHODS The lead and tin used were of high purity. They were supplied by the American Smelting and Refining Co., who gave the following analyses: Lead: silver, 0.0016 oz per ton; copper, 0.0008 pct; cadmium, 0.0007 pct; zinc, 0.0002 pct; arsenic, 0.0003 pct; antimony, 0.0002 pct; bismuth, 0.0005 pct; tin, 0.0001 pct; iron, 0.0020 pct; lead (by difference), 99.995 pct. Tin: antimony, 0.037 pct; arsenic, 0.020 pct; bismuth, 0.004 pct; cadmium, trace; copper, 0.025 pct; iron, 0.004 pct; lead, 0.020 pct; nickel and cobalt, 0.005 pct; silver, 0.0005 pct; sulphur, 0.005 pct; tin (by .-difference). 99.88 pct. One hundred grams of metal with the desired proportions of lead and tin was weighed out to the nearest one-tenth of a milligram. The mixture was placed in a silica crucible, covered with charcoal, and melted in a reducing atmosphere in a gas-fired furnace. The alloy was well stirred. Chemical analysis of two of the alloys checked closely with the weighed portions. The compositions of the remainder of the alloys were taken directly from the weighings, without chemical analysis.

Jan 1, 1950

By Peter W. Lipman

Structural and topographic relief in the Sangre de Cristo Mountains of northern New Mexico provides a remarkable cross section through the recently recognized 23-26 m.y.-old Questa caldera and cogenetic volcanic and plutonic rocks. Although largely eroded, remnants of an ash-flow sheet of silicic-alkalic rhyolite and associated more mafic lavas of the Latir volcanic field are preserved as far as 45 km beyond the source caldera. Within the caldera, the tuff ponded to a thickness of 2-3 km and enclosed chaotic megabreccia fragments which slumped from the caldera walls. At the time of ash-flow eruption, the volcanic field was severely deformed along northwest-trending faults related to the Miocene Rio Grande rift, with most intense deformation occurring within the caldera. Strata were steeply tilted and locally overturned along presumably listric faults. Ash- flow tuffs locally underwent secondary flowage over concurrently developing fault scarps and accumulated within structural basins as rheoignimbritic lava flows. Cogenetic batholithic granitic rocks, exposed over an area of 20 x 35 km, range from mesozonal quartz monzonite to epizonal porphyritic granite and aplite, with the shallower and more silicic phases most abundant within the caldera. Compositionally and texturally distinct granitic phases define a highly evolved resurgent intrusion within the caldera, an incomplete ring dike along its southern margin, and a large mass of less fractionated quartz monzonite south of the caldera. A negative Bouguer gravity anomaly is closely confined to the area of ex- posed granitic rocks; it also reflects boundaries of the Questa caldera. The gravity anomaly is interpreted as defining the extent of the underlying batholith, emplaced into lower parts of the volcanic sequence and underlying Precambrian rocks. Paleomagnetic determinations indicate that the granitic rocks were above Curie temperatures at the time of caldera formation and regional listric faulting, yet most are little different in radiometric age from the intensely deformed volcanic rocks. These relations indicate that the batholithic complex represents the source magma body for the volcanic rocks, into which the Questa caldera collapsed, and was largely liquid at the time of regional tectonic disruption. Compositions of the volcanic and plutonic phases changed from early calc-alkaline metaluminous rocks, to weakly peralkaline silicic rhyolite and equivalent afredsonite-acmite granite at the time of the caldera formation, then back to post- caldera calc-riebeckite granitic rocks. Maximum concentrations of alkalis and minor elements such as Rb, Th, U, Nb, Zr, and Y were reached at the time the caldera formed about 25-26 m.y. ago, but the major molybdenum mineralization of the Questa district took place when the late calc-alkaline granitic ring intrusions were emplaced about 23 m.y. ago, along the south margin of the caldera.

Jan 1, 2013

By M Bouare, C Holland, K N’Diaye

Two adjacent open pits in Mali hosted by deeply weathered saprolitic materials were mined consecutively over the course of approximately 12 months. During excavation, both pits experienced significant displacement and tension cracking as the result of deeper than expected depth of weathering coupled with relatively steep slope angles and significant groundwater. In response, geotechnical and operations teams overcame numerous monitoring challenges with prisms and radar to develop a simple and effective monitoring system coupled to a Trigger Action Response Plan (TARP) which enabled continued safe operations while reducing ore loss. Observations of previous slope performance of these two pits allowed for greater confidence in empirical failure runout calculations that was used to specify the standoff widths for the exclusion zones in the pit. Back analysis of the slope as-built performance after the first indications of slope distress was also conducted. The back analysis was used to confirm rock mass parameters for modelling while being utilised as a reality check for the stability analysis. The stability analysis indicated that leaving a large step-out or buttress would not prevent the displacement, resulting in some ore being sacrificed to ensure the safety of personnel. Key learnings from this experience highlight the importance of: • up-to-date geological interpretation of the depth of weathering • ensuring slope design guidance is reviewed and updated as latest information (ie geology and monitoring) is received • having multiple complementary slope monitoring methods to ensure redundancy • ensuring visual observations and as-built performance are utilised as a reality check to provide greater confidence in stability analysis and design guidance.

Jun 22, 2022

By Luiz A. Teixeira

This paper reports the results of kinetic studies involving the precipitation of arsenic from aqueous solutions as FeAs041 Fe(OH)3&apos; using FeS04 as source of Fe ions, and Air or H202 as oxidizing agents. Both systems lead to an efficient removal of arsenic. The differences in oxidants performances are in the precipitation reaction rate -much faster using hydrogen peroxide. Mechanisms of reactions were suggested based on the following main steps:

Jan 1, 1996

By Donald F. Reed

The bauxite deposits of Tippah and Benton Counties in northeastern Mississippi were developed by drilling as a part of the investigation by the Bureau of Mines of the domestic sources of supply of aluminum. The primary purpose of investigations of this nature was to provide essential information to the war agencies of the United States Government and to assist owners and operators of mining properties in the production of minerals vital to the prosecution of the war. These reports are based upon the field work of the Bureau of Mines and upon data made available to the Department from other

Jan 1, 1948

By L. G. Trudell, J. W. Smith, K. E. Stanfield

Representation of actual oil yields from sections of the Green River formation oil shales by two types of drill - cutting samples was evaluated . Average oil yields of single sets of mud cuttings from hydraulic rotary drilling in Colorado and gas cuttings from pneumatic rotary drilling in Utah were compared statistically with yields of core samples taken from adjacent holes . Oil yields from gas cuttings were identical to oil yields of core samples . Mud cuttings appeared to represent a section of the formation conservatively , the deficiencies increasing with increasing richness of sample . Because a large amount of the oil - yield data currently available for the Green River formation is based on mud- cutting samples , development of a valid correction method by additional testing is needed .

Jan 1, 1963