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By Fred C. Bond

MOST investigators are aware of the present unsatisfactory investigatorsstate of information concerning the fundamentals of crushing and grinding. Considerable scattered empirical data exist, which andare useful for predicting machine performance and give acceptable accuracy when the installations and materials compared are quite similar. However, there is no widely accepted unifying principle or theory that can explain satisfactorily the actual energy input necessary canexplain commercial installations, or can greatly extend the range of empirical comparisons. Two mutually contradictory theories have long existed in the literature, the Rittinger and Kick. They were derived from different viewpoints and logically lead to different results. The Rittinger theory is the older and more widely accepted.'TheRittinger In its first form, as stated by P. R. Ritted.'tinger, it postulates that the useful work done in crushing and grinding is directly proportional to the new surface area produced and hence inversely proportional to the product diameter. In its second form it has been amplified and enlarged to include the concept of surface energy; in this form it was precisely stated by A. M. Gaudin' as follows: "The efficiency of a comminution operation is the ratio of the surface energy produced to the kinetic energy expended." According to the theory in its second form, measurements of the surface areas of the feed and product and determinations of the surface energy per unit of new surface area produced give the useful work accomplished. Computations using the best values of surface energy obtainable indicate that perhaps 99 pct of the work input in crushing and grinding is wasted. However, no method of comminution has yet been devised which results in a reasonably high mechanical efficiency under this definition. Laboratory tests have been reported- hat support the theory in its first form by indicating that the new surface produced in different grinds is proportional to the work input. However, most of these tests employ an unnatural feed consisting either of screened particles of one sieve size or a scalped feed which has had the fines removed. In these cases the proportion of work done on the finer product particles is greatly increased and distorted beyond that to be expected with a normal feed containing the natural fines. Tests on pure crystallized quartz are likely to be misleading, since it does not follow the regular breakage pattern of most materials but is regularrelativelybreakage harder to grind patternat the finer sizes, as will be shown later. This theory appears to be indefensible mathematically, since work is the product of force multiplied by distance, and the distance factor (particle deformation before breakage) is ignored. The Kick theory4 is based primarily upon the stress-strain diagram of cubes under compression, or the deformation factor. It states that the work required is proportional to the reduction in volume of the particles concerned. Where F represents the diameter of the feed particles and P is the diameter of the product particles, the reduction ratio Rr is F/P, and according to Kick the work input required for reduction to different sizes is proportional to log Rr /log 2." The Kick theory is mathematically more tenable than the Rittinger when cubes under compression are considered, but it obviously fails to assign a sufficient proportion of the total work in reduction to the production of fine particles. According to the Rittinger theory as demonstrated by the theoretical breakage of cubes the new surface produced, and consequently the useful work input, is proportional to Rr-l.V f a given reduction takes place in two or more stages, the overall reduction ratio is the product of the Rr values for each stage, and the sum of the work accomplished in all stages is proportional to the sum of each Rr-1 value multiplied by the relative surface area before each reduction stage. It appears that neither the Rittinger theory, which is concerned only with surface, nor the Kick theory, which is concerned only with volume, can be completely correct. Crushing and grinding are concerned both with surface and volume; the absorption of evenly applied stresses is proportional to the volume concerned, but breakage starts with a crack tip, usually on the surface, and the concentration of stresses on the surface motivates the formation of the crack tips. The evaluation of grinding results in terms of surface tons per kw-hr, based upon screen analysis, involves an assumption of the surface area of the subsieve product, which may cause important errors. The evaluation in terms of kw-hr per net ton of —200 mesh produced often leads to erroneous results when grinds of appreciably different fineness are compared, since the amount of —200 mesh material produced varies with the size distribution characteristics of the feed. This paper is concerned primarily with the development, proof, and application of a new Third Theory, which should eliminate the objections to the two old theories and serve as a practical unifying principle for comminution in all size ranges. Both of the old theories have been remarkably barren of practical results when applied to actual crushing and grinding installations. The need for a new satisfactory theory is more acute than those not directly concerned with crushing and grinding calculations can realize. In developing a new theory it is first necessary to re-examine critically the assumptions underlying

Jan 1, 1953

"This paper describes some of the methods and equipment used for fine milling of minerals, and gives particular attention to the Vibro Energy system.In addition, the paper describes a specific application in the gold mining industry. This is the 200 tpd plant built by Anglo American Corporation at the President Brand Mine in South Africa in 1985, now a division of Freegold. This plant treats a gold bearing pyrite flotation concentrate which is finely ground to 15 microns prior to cyanidation and carbon-in-pulp (CIP). l .0 INTRODUCTIONFree milling gold ores are those that yield acceptable dissolution and recovery of the gold following grinding to what can be described as normal fineness, frequently between 50% and 90% passing 74 microns.Increasingly, gold metallurgists are faced with ores that are refractory. The traditiona1 treatment route for refractory gal d ores and concentrates has been by roasting, but for environmental reasons this is becoming less acceptable, or in some areas of the world, totally unacceptable. New methods of treating refractory gold ores are being developed and applied in practice. These new methods include pressure and biological oxidation. Higher gold liberation can also be attained by increasing the fineness of grind, although with conventional systems there are economic limits to this.In flowsheet development and test programs on new deposits, a standard procedure is to establish the relationship between the grind and subsequent go 1 d extraction. The normal situation is that gold extraction increases as the ore, or concentrate, is ground finer. Typically, this relationship is as shown in Fig. l, where the incremental additional extraction is very small once an optimum, or economic, grind has been achieved. This generally app1ies whether the material is free milling or refractory. The limits to grinding are set by the type of equipment which is commonly in use, usually ball mills. These mills have the obvious advantage of high capacity, however, they are increasingly inefficient as finer grinds are required. In general, ball mills are used to reduce ore to some agreed percentage passing 74, or possibly 53 microns."

Jan 1, 1988

By Paul Sainato

Recruiting and retaining students in the explosives industry is becoming increasingly important each year. With no undergraduate degree in explosives engineering currently available in the United States, it is from other industries and degree disciplines we must recruit. The 2014 annual ISEE conference saw the first anonymous online survey distributed to members of SEE student chapters of the International Society of Explosives Engineers. The survey contained questions about future job and career plans, ideal job placement, expectations of salary and current academic degrees. The purpose of the survey was to determine what these students expect or require from a career in the explosives industry, and their current path to pursue this. This information can help steer recruitment activities and job offers for graduating students. The success for both student response rates and interest from the industry has allowed space for a yearly update of this survey. A second survey was distributed in 2015 and included international students. This paper provides the data from a third online survey distributed to all student members of the International Society of Explosives Engineers, globally. Understanding the main incentives for a student to accept a graduate position as an explosives engineer can help us, as an industry; position ourselves to remain competitive in recruiting against other major degree disciplines.

Jan 1, 2016

By J. H. Jacobs

In late 1946, research was begun at the Bureau of Mines Electrometallurgical Laboratory at Boulder City, Nev., to determine the possibility of electrowinning manganese from chloride electrolytes on a continuous basis. All phases of electrodeposition were investigated on a small scale it the laboratory, and the results were reported by Jacobs and Churchward. These results indicated that a chloride process had certain possible advantages over the sulfate process that made it worthwhile to continue the investigation on a semi-pilot-plant basis, and this paper reports the results of this work. Research and development work on a process for electrowinning manganese from low-grade ores has been carried on intermittently by the Bureau of Mines since 1936. A process was developed, using sulfate electrolyte, that has been extensively described in the literature.

Jan 1, 1951

By Shreya Vivek Hokam, Dr. A. I. Dhatrak, S. W. Thakare, Dr. Vivek S. Hokam

Construction in congested urban areas has necessitated tall and massive structures. In urban areas, it is common to construct underground structure nearby existing buildings. Selection of an appropriate support structure system to be implemented in the excavation in an urban area is heavily dependent upon the geotechnical conditions and safety of the surroundings and neighbouring structures. Urban Rail, popularly referred to as Metro Rail, has seen substantial growth in India in the recent years. More cities are experiencing the need for metro rail to meet their day-today mobility requirements. The metro structures involved deep excavation for foundations which induces the stresses and thereby alters the existing equilibrium and thus may affect stability of neighbouring structures considering safety point of view. Hence, design and execution of deep excavations become one of the important challenging tasks of any geotechnical engineer in the modern era. Further, it is important to control the ground movement in order to prevent the failure of excavations. This involves specialized foundation technologies, usage of sophisticated equipment and new methods in underground construction, safety and monitoring systems. In this paper the methodology used for protecting adjoining structures due to deep excavation for Nagpur Metro station is studied.

Sep 1, 2022

By Luis Emylnn Salas

If the ordinary wet method be attempted for silver-bullion containing tin, much trouble is experienced, varying with the amount of tin present. Even with a percentage as low as 0.05, the end-point is masked by a persistent turbidity, while with amounts ranging from 0.5 per cent. upward, the determination of the exact end-point is impossible, owing to the finely divided or colloidal metastannic acid resisting all efforts to cause it to settle, or to give a clear supernatant liquid. The object of the following experiments was to seek a remedy for these difficulties, and to find the conditions whereby the Gay Lussac method might be applied directly to these bullions. Material containing tin is met with frequently in bullion from Mexico or Bolivia; and tin is carried (sometimes in large quantities) in jewelers' sweeps. 1. A bullion was prepared containing Ag, 74; Cu, 25; and Sn, 1 per cent. A weighed amount was treated by the humid assay-method as if it were an ordinary bullion free from tin. Ten cc. of HNO, (1.21) was added, and the bottle was heated until all traces of

Jan 1, 1913

By Marius R. Campbell

VARIOUS classes of coals are recognized in this country at the present time. These classes depend largely upon physical characteristics rather than upon chemical composition, and consequently they cannot be accurately defined. The divisions into anthracite, semi-anthracite and semi-bituminous are fairly satisfactory; but the term bituminous embraces so large a variety of coal that it is of little value, and the term lignite is so loosely applied that it has little or no place in a scientific classification. At present there is no way of accurately defining the vari¬ous classes of coal, because no adequate scheme of classification, which applies to lignites as well as bituminous coal and anthracite bas been proposed. The object of this paper is to present such a scheme, which is based upon data obtained dur¬ing the past year by Prof. N. W. Lord,1 in charge of the chemical laboratory of the United States Geological Survey coal-testing plant at the Louisiana Purchase Exposition, St. Louis. All the classifications of coals proposed prior to 1877 were based either on physical characteristics or on proximate analyses, including all of the impurities. These schemes were illogical and highly unsatisfactory, for the physical properties of a coal give little indication of its true composition; and impurities, such as ash and sulphur, are largely the results of acci-

Sep 1, 1905

By J. Chai, Y. Qiang, D. D. Zhang

"In order to control Quaternary loose layer settlement in East China, there are monitoring results based on the 3 water level observation holes and 7 sand layer of fiber Bragg grating (FBG) strain sensor. Un-der the conditions of upper group water injecting to lower group of loose layer, the deformation characteristics of upper, middle and lower group of loose sandy soil layer changing with time and relationship with the water level are studied. The constitutive relation of stress-strain is also studied at different sand layers. Research results show that using water injecting from upper group into lower group of loose layer can ease the loose layer compression deformation. With the water level dropped, in East China soil creep deformation occurred, which accord with viscoelasto plastic model. The deformation of lower sand group has clear later effect and no direct relationship with water level. The results provide an important basis for the study East China stratum settlement model and water management. INTRODUCTION Ground-surface subsidence is a common geological disaster, which has the features of continuous, changing slowly, concealment (Y.P. Yin et al. 2005). Today, due to underground mining and constructions in formation compression, surface subsidence is wide-spread in the world, which is the environmental geological problems in the worldwide that cannot be ignored (Y.Q. Xu et al. 2006, D.L Gallo-way et al. 2000, Qiu, B. et al. 2011). The eastern region of China has generally geological disasters in coal mine geological caused by the thick loose layer settlement like as mine shaft failure. Stratum dehydration consolidation is a major cause of loose layer settlement (H.Y .Liu et al. 2007). A method of water injection using ground water to stable water level is proposed, which can effectively control the loose layer caused by compression settlement(J. Chai et al. 2012&.2013). Accurately knowledge the characteristics of strata deformation is the premise of settlement management (Q.C. He et al. 2006). Previous re-search (J.F. Miu et al. 1996, X.Y. Gu et al.1998, Y. Zhang et al. 2006), mainly studies are focused condition of the city pumping irrigation, de-formation characteristics of middle and up loose layers. On a group of aquifer in East China, the loose layer losing water is caused by coal mining, bottom water drainage and overlying strata water flowing fractured zone hydrophobic induced by mining, which the dehydration conditions have great difference from one to another. The Position of water loss is centralized in bottom aquifer, and the formers of ground subsidence geological environment and settlement mechanism are different. According to the study of stratum settlement, usually the de-formation of sand layer is ignored(C.H. Liu et al. 2004), but few studies show that the sand layer have the plastic deformation, and contains the creep deformation, water content of sand soil may become the main settlement layer (Z.X. Wei, 2002, C.H. Liu et al. 2004)."

Jan 1, 2015

By R. Minango

Solvent extraction of Cu from acidic leach, using an oxime extractant, e.g. LIX 984 or Acorga is a well-known and establishedprocess. As the process advances, Cu is extracted to the solvent and is replaced by H+in the aqueous phase. At high acidity the distribution coefficient of Cu between the solvent and the aqueous phase decreases, and eventually a relatively high concentration of Cu remains in the raffinate, regardless of the number of equilibrium stages. In many processes this phenomenon is immaterial, as the raffinate returns to the leaching and no copper is lost. But when the copper raffinate is used for processing of additional metals, minimal concentration of Cu in the raffinate is essential for an effective process. The recommended process includes three steps: SX-1?standard extraction of Cu with oxime. The resulting raffinate contains about 6?8 g/lCu and 50 g/lH2SO4. SX-N?Extraction of most of the acid into an amine-based solvent, and stripping it with a base, e.g. aqueous ammonia, caustic, Na2CO3etc. The extraction removes no metals, but decreases the concentration of acid from 50 to10 g/l. SX-2?Extraction of the neutralized solution once more with oxime, to remove the residual copper. Such a process enables one to get down to 100?150 ppm Cu in the final raffinate. This process was developed and tested in the R&D facility at Chambishi Metals plc, by a joint team of Chambishi & Bateman, using Cognis LIX 984N and real solutions from the plant. In the laboratory the equilibrium isotherms for SX-1, SX-2 and the neutralization were developed. Computer simulation of the results showed that the optimal configuration is two stages for both extraction and stripping for SX-1. For SX2, 2?3 stages of extraction and two stages of stripping are needed. The stripping stages may be common to both SX-1 and SX-2. The neutralization of SX1 raffinate was tested both by conventional precipitation with lime and by extraction with alamine-based solvent extraction and stripping with a solution of 10% NaOH. For the SX-N only one stage was needed for both the extraction and stripping. The bench scale pilot plant was run for both SX-1 and SX-2. The results were very similar to the simulated ones, and the configuration of 2E2S for SX-1 and 3E2S for SX 2 delivered the required raffinate with less than 150 ppm Cu.

Jan 1, 2005

By G. C. Sun

Rock mechanics properties, i.e. uniaxial and triaxial compressive strength, indirect tensile strength shear strength, Young's modulus, and poisson's ratio were collected for coal and related strata from 50 coal seams in 90 mines. The methodology of data organization and retrieval is described in details. The values and .ranges of those properties are also discussed.

Jan 1, 1993

By Nicol S. K, Firth B. A

Much effort over the years has been put into the task of devising parameters which adequately assess the metallurgical efficiency of mineral processmg operations. One of the most celebrated of these methods is the so-called "release analysis" method of Dell (1953) which tackles the problem in terms of an ideal separation based on sequential retreatment of the products and tails of a given separation process. Other methods have also been proposed by Jowett (1969) and by Holland-Batt (1971 ). While these procedures are appropriate to multi-component mineralogical separations, they perhaps do not lend themselves to the much more simple two-component systems encountered in coal preparation. However Dell (1962) has suggested the use of the term "specific profit" in coal preparation in order to assess the conditions that give maximum economic gain. Specific profit is derived from data relating washability data with equipment performance and operating costs. The procedure for using this criterion for comparative purposes is therefore somewhat cumbersome as is illustrated by its lack of widespread acceptance in the coal preparation literature.In contrast, an efficiency index, E, which is both simple and meaningful from the utilitarian standpoint, has been proposed by Tsiperovich and Evtushenko (1959a). This index is defined by the relation, E = Yield X Tailings ash/Product ash (1) A cursory examination of this parameter shows that it increases when yield and tailings ash increase and also when product ash decreases; all of which are desirable circumstances in coal cleaning operations.Further, it will be shown that slight variations in operation are amplified by this function which makes comparisons simple and direct.While the use of this index is quite extensive in the Soviet coal preparation literature for some reason it has not received wide usag~ elsewhere.

Jan 1, 1978

By J. A. Sweet, T. BACHMANN, G. E. Sandoval, T. M. Hauyon, F. A. Contreras

In many respects a porphyry copper ore concentrator plant can be considered as a simple system. Chalcopyrite typically liberates well at relatively coarse sizes, and even low grade ores are amenable to upgrading 20 to 30 times to produce concentrate grades in excess of 25 % in very simple Rougher- Regrind-Cleaner+Scavenger flotation circuits. The flotation response of chalcopyrite has been well characterised in many fundamental and applied research studies and the conditions necessary to depress pyrite and other floating gangue species are well understood. But what happens to the particle surfaces when you have a 50 km pipeline between the grinding circuit and the flotation plant? How does the seasonal variation in water quality affect your ability to control pulp chemistry? What impact does the relative concentration of the different sulphide species have on their separability? Why do two plants that receive nominally the same ore produce consistently different results? And most importantly, what do you need to do to improve the performance of both plants? To answer these and other questions, a focussed sampling and analysis programme was carried out at the Las Tórtolas flotation plants in 2018 and 2019. The work included full down-the-bank sampling, hot floats, the use of radioactive tracers for determining residence time distribution profiles, gas dispersion measurements, detailed mineralogy by size across the circuits and multiple regrind surveys. This comprehensive study was augmented by analysis of historical mineralogy, geometallurgy and operating data using modern data science techniques, and has provided the foundation for current and future optimisation initiatives. Some of the findings and their implementation will be presented in this paper. Keywords: Circuit optimization, Residence time, Gas dispersion, Pulp chemistry

Jan 1, 2020

By Stephen Phillips, Luigi P. Gonano

Vertical circular shafts have been proposed for multiple access to high level nuclear waste deep geologic repositories. Shaft construction is a critical path item in the commissioning of a repository. Other constraints on the shaft design and construction criteria include the lack of design precedence for long term performance and the importance of minimizing rock and groundwater disturbance. A comparative evaluation of conventional and mechanized shaft sinking techniques is presented in the context of the particular geologic and design constraints. Technical and non-technical factors for blind drilling, blind boring, raise-reaming, drill-and-blast and ream-and slash methods are reviewed for typically "hard rock" and "salt" type repository sites. Appropriate shaft designs are developed, the suitability of each method to the particular requirements evaluated and construction costs and schedules determined. The explicit appraisal of the significant design factors for each method serves as a rational basis for the preliminary selection of the most suitable sinking technique for a particular set of site/design conditions.

Jan 1, 1983

By D. S. Jacobus

COMPRESSED-air motors are specially desirable, if economically practicable, for underground haulage, because they require no fuel, involve no danger of fire, and not only avoid heating and fouling the atmosphere with smoke and combastion-gases, but by the emission of expanding fresh air, cool and improve it and aid ventilation. The highest developments in the use of compressed-air motors for locomotion are to be found, in the opinion of the writer, in the principles of the Mekarski car-motor as applied to street tramways, and it is thought that notes taken regarding this system, during a recent trip to Europe, where two plants are in successful operation, at Nantes and Vincennes respectively, will be interesting to mining engineers. The plant at Nantes operates a street-line 5.2 miles long, requiring about twenty motors; the one at Vincennes about 7 miles of road. Each car at Nantes carries its own motor. At Vincennes, however, the motor-car is arranged to tow a second car containing no motor. The road at Nantes is the older, having been in successful operation for ten years, during which time neither the American consul, Mr. Shackelford, who has resided at Nantes for about five years, nor the vice-consul, Mr. Bennett, who has been at Nantes ever since the road started, has ever seen anything go wrong with the motors. DESCRIPTION OF THE RAILROA at Nantes. Motor-Car.—Two small engines are connected' so as to rotate the front axle of the car, a reversing lever being used to alter the cut-

Jan 1, 1891

global mining boom and in-creased demand for iron ore has lead to a resurgence in the mining industry in Minnesota. At the combined 81st Annual Minnesota Section of SME Meeting and 69th Annual University of Minnesota Mining Symposium, April 15-16 in Duluth, MN, this resurgence was the hot topic as new mining projects were featured in the keynote session. The meeting attracted more than 400 mining industry professionals, including engineers, executives, mining managers and suppliers from around the world. This year?s theme was ?New Ventures in Mining.? The meeting included concurrent technical papers sessions, a keynote session that featured three distinguished speakers and a panel discussion that provided updates on new mining developments in the state. The Minnesota Section of SME technical papers were presented in concurrent sessions, one on mining and one on mineral processing. The mining session included papers on drilling, ore blending, slope stabilization, dust control and operations management. The mineral processing session included papers on plant-control technology, ball mills, pellet strength and fans. Also offered was an SME short course titled ?Simulation based pellet induration optimization.? The Minnesota Section of SME held its annual business meeting during the conference. The 69th Annual University of Minnesota Mining Symposium technical sessions were held on April 15 and also consisted of concurrent sessions on mining and mineral processing. Mining session topics included logistics management, real-time performance measurement, uses for taconite aggregate and environmental issues. The mineral processing session included papers on ore liberation characteristics, zeta potential studies, induration modeling, fuel optimization and conveyor belts. The combined conference included a tradeshow with more than 80 booth spaces featuring vendors offering products and services to Minnesota?s booming mining industry. More than 900 people, including conference registrants and special invited guests of the vendors, at-tended the tradeshow opening reception. This was the largest trade show in many years ? an indication of the vitality of the mining industry in Minnesota.

Jan 1, 2008

By D. Diering

Having agreed to perform this task, I naturally started to wonder what on earth I was going to talk about, and on reviewing the literature I was surprised at how little I knew and how much I?d forgotten about the origins of this industry. For example: ?I?d forgotten that the Chinese invented black powder at least 1 000 years ago, back in the 10th century (although some say this invention occurred 2 000years ago). ?I didn?t know that Roger Bacon was the first person in the Western World to give exact directions for the making of gunpowder in 1242 and to understand its potential. Pepper?s Playbook of Metals quotes:?...above all, he is named as the discoverer of gun-powder, a material which has brought more wonderful changes in the great family of man than the most potent elixir that could have been devised to prolong life?.

Jan 1, 2000

By J. P. Rider

The number of extended cut mining systems has increased significantly in coal mines over the last decade, and there is a constant push to extend the face ventilation systems to even greater setback distances. The need to maintain airflow at setback distances of 12.2 m (40 ft) and beyond requires that methods for delivering intake air to the face be improved, or alternative ventilation techniques be implemented. The emphasis of this research effort was to examine various techniques to improve the distribution of available air at the mining face in order to reduce face methane levels. A study was conducted comparing the performance of a jet fan, used in conjunction with a machine mounted scrubber, with blowing curtain ventilation in a 27.5 m (90 ft) heading. In addition, a second study was performed on blowing curtain systems examining how scrubber flow, intake air velocity, and curtain setback influence face methane concentrations. Results showed that when the heading advances to a depth of 27.5 m (90 ft) blowing curtain systems were more efficient at diluting face methane levels when compared to a jet fan. Also, increases in scrubber flows and curtain velocity resulted in lower face methane concentrations for blowing curtain systems at 9.2 and 15.2 m (30 and 50 ft) setbacks.

Feb 24, 1997

By J. Drelich, M. Pawlik

An improved experimental procedure to measure contact angle has been consolidated with coal surface preparation involving polishing with abrasive paper, alumina powder, and a cloth, followed by ultrasonic and mechanical cleaning. Specifically, the captive-bubble measuring technique has been compared with the sessile-drop technique and the former has been recommended for the examination of the hydrophobic properties of coal surfaces. Results of the research program, which is currently under way, on the examination of the effect of the nature, amount, size, and distribution of mineral inclusions in coal, on its wettability are briefly reviewed.

Jan 1, 1999

By W. G. Worcester

IN the presentation of this paper to the Institute, three objects are in the mind of the writer: first, to set forth the close relation which, of necessity, exists between ceramics and the industrial minerals; second, to clarify the apparently hazy understanding which many have of ceramics in general; and lastly, of equal or even more importance, to stimulate a greater interest in the industrial minerals, especially in those used and required by the ceramic industries. While Canada is now producing in large quantities a fairly wide variety of the ceramic industrial minerals, there are some which are not known to occur in the Dominion. Hence it is to be desired that our geologists, prospectors, and others, while on field work, should be on the look out for commercial deposits of such minerals as diaspore, bauxite, ucts of a value in excess of $600,000,000, a figure which places ceramics as kyanite, massive topaz, and sillimanite. A find of any of these in quantity would prove of very great importance and value to the country as a whole. At this point it seems desirable to introduce formally the word ceramic or the plural of it, ceramics. In doing so it may be stated that the origin of the word dates far back in history in that it was derived in part from the Greek word Keramos, 'a potter' or 'pottery', which in turn has been traced back to an older Sanskrit root meaning 'to burn' or 'burned stuff', having reference, no doubt, to burned pottery or other clay wares; and the word was so used until near the close of the last century, when the world's first schools of ceramic engineering were established in the United States. The use of the term ceramics was then expanded to cover a much larger field the entire field of the silicate industries and products. At one time it was suggested by a limited number of ceramists that the term 'ceramic engineering' be changed to 'silicate engineering'. This proposal, however, gained little support and was soon abandoned.

Jan 1, 1945

By A B. Christie, F P. Bierlein

Lode gold deposits of the Western and Eastern provinces, South Island, New Zealand , formed as a part of the Cordilleran-style tectonism during Tasman/Tahua and Rangitata orogenesis along the Paleozoic-middle Mesozoic southern Gondwanan margin. These deposits, hosted by lower grade greenschist facies sedimentary rock sequences of the Buller, Takaka, Torlesse, and Caples terranes, universally show geological features that are consistent with the orogenic gold deposit model, and genetic features are generally suggestive of a metamorphic origin, with the possible exception of a magmatic fluid source for the mineralisation at Sams Creek. However, ore fluid chemistry in Mesozoic deposits of the Eastern province, particularly the low concentration of non-aqueous volatiles and the very dilute nature of the fluids, is uncharacteristic of most orogenic gold deposits; this must be explained by either a unique fluid source or fluid type, which we believe unlikely, or an unrecognised significance of relatively rare gas-rich fluid inclusions in the deposits. Absolute age data for gold deposits in both provinces remain equivocal, thus hindering definition of the exact temporal relationship between ore formation and terrane accretion, regional metamorphism, and magmatic arc emplacement. Mercury and antimony occurrences in subgreenschist grade parts of the Haast Schist may target the upper levels of unrecognised orogenic gold deposits. If low-grade, high-tonnage intrusion-related gold systems occur on the South Island, then they are most likely to be discovered in association with the small molybdenite-, scheelite-, or cassiterite-bearing quartz stockworks spatially related to the Karamea and Median batholiths.

Jan 1, 2005