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By John C. Nixon

In 1959, The Australasian Institute of Mining and Metallurgy (Aus. I.M.M.) was asked by the Federal Government of Australia and the State Government of South Australia to join in the formation and management of a new contract research organization which was subsequently named The Australian Mineral Development Laboratories (Arndel) ? This body was formerly the Research and Development Branch of the South Australian Department of Mines which had been set up to develop the Radium Hill uranium deposit. It had then gone into contract R&D and the State felt that it would be more appropriate for the Branch to become a separate national organization. The Aus. I.M.M. decided that a professional institute could not participate directly in Arndel and, as there was no other suitable industry group to do so, it formed the. Australian Mineral Industries Research Association Limited (AMIRA). AMIRA held its first Annual General Meeting in September 1959 when the first Council was elected and the Memorandum and Articles of Association were adopted. The initial task of AMIRA was to raise guarantees of work or cash from its members to underwrite Arndel for the first five years of operation. The Federal and State Governments also provided guarantees and Arndel commenced operations in January 1960.

Jan 1, 1977

By J. D. Noll, J. A. Organiscak, A. B. Cecala

Over the past decade, a substantial effort has been made to improve the air quality inside enclosed cabs of both underground and surface mobile mining equipment to reduce respirable dust exposures by the equipment operators. As part of this effort, the U.S. National Institute for Occupational Safety and Health, (NIOSH) completed a comprehensive laboratory study that determined the significant factors for cab filtration and pressurization systems. From this information, a major underground mining equipment manufacturer designed a filtration and pressurization system that was incorporated into the enclosed cabs of its equipment. A long-term evaluation was performed on the effectiveness of this filtration and pressurization system to improve the air quality in the enclosed cabs of two different pieces of equipment, a face drill and a roof-bolter machine, at an underground limestone mine. This long-term evaluation demonstrated a significant reduction in dust levels between outside-to-inside cab respirable dust concentrations. During this evaluation, a modification to remove one of the filters on the roof-bolter machine simplified the design without sacrificing the system’s efficiency. Tests using particle count instruments performed during nonproduction time periods on both pieces of equipment indicated protection factors greater than 100 when comparing respirable-sized dust particles inside the enclosed cab relative to outside.

Jan 1, 2012

By R. Bruce Thorndycraft

This paper will describe several modifications to design of con­ventional oxide gold heap leaching. They are targeted at reduc­ing costs and simplifying heap operations. These modifications were conceptualized during consulting work on over 90 differ­ent heap leaches. In 1995, a unique opportunity arose to imme­diately apply all of these design concepts to the permitting and construction of a new facility at the American Girl Mine in southeastern California. American Girl Mine has operated since 1987. In April 1995, the mine faced a situation with grave consequences for cash flow. Approval for mining of a new ore zone, Oro Cruz, had just been granted, after lengthy delays by California regula­tors. All existing pad space would be filled by October. Only 6 months were available, and new pad siting and design were still undecided. Permitting of a new pad had not begun. Options were quickly reviewed. A strong criteria for pad site selection and design was ease of permitting. There was also a strong desire to install a system that would achieve better met­allurgical recovery and reduced operating costs, compared to previous heaps at this mine. One site offered the best chance for rapid permitting. It was the site of the original 1987-90 heap leach. This already dis­turbed ground contained 1.6 million tons of heaped ore. The old heap had just completed detoxification and was about to be signed off as a Group C waste, ready for reclamation. Instead of recontouring and revegetating the old heap, which the reclamation plan anticipated, we offered BLM and the County something even better. We proposed to off-load much of the detoxed old heap, and reuse the space. The off-loaded material would be back-filled into the original open pit, imme­diately adjacent. While the footprint of the proposed new pad was much larger, the reuse of disturbed ground, and backfilling of the open pit, had very strong appeal to the regulators. Our permitting strategy included the technical design of the proposed new facility. Many of the new design details also appealed to the regulators, particularly the "zero active ponds" concept.

Jan 1, 1996

By Xin Jingmin

The present trend toward concentration of mining activities into fewer sections of a coal mine and application of automation and remote control technologies favor utilization of the longwall mining method. Longwall mining also offers the potential for improving safety and productivity, better ground control and higher levels of recovery. The production potential of a longwall operation is determined by the interaction of several factors including the rate of face advance, the thickness of extraction, the speed of cutting and hauling equipment, the physical dimensions of a longwall panel, and the reliability and availability of the equipment. Some of these factors are dictated by the environment in which the extraction process is to be undertaken. Some other factors, however, can be manipulated in order to optimize the production of the system. The objective of this paper is to develop a stochastic model to simulate the production operations in longwall mining. The activities and parameters that affect the production potential of the longwall operations and the relationships between the activities are identified. An attempt is made to verify these relationships through the use of existing data. The model is then used as a computer simulator to investigate the effects of various activities and parameters on the production capacity of a panel.

Jan 1, 1983

By B. Cavender

Investments in new technology are often intended to improve the production or cost performance of existing operations. The economics used to justify these projects can be flawed, however, if they do not adequately consider the potential benefits of the alternative: the fully optimized use of the facility's present equipment and personnel. While new technology can be effective, dramatic improvements in production performance can also be achieved through the rigorous application of standard industrial engineering and operations management practices. An intermediate approach may also be effective: many basic improvements in the mine or plant necessary to support new technology will be equally effective when implemented for the facility's present operators. Firms that optimize their present operations are able to save the capital and avoid the risk associated with new technology. These firms will also be able to capitalize more quickly on new technology when it is implemented.

Jan 1, 2000

By Colin J. Douch

New Zealand has been a significant producer of gold for over a century. Total recorded production is over 850 tonnes. There were three major periods of production: the first and biggest was between 1860 and 1880, the second was between 1895 and 1920 and the third was between 1930 and 1945. After 1945 gold production fell continually until 1980 when the major upward adjustment in gold price led to renewed interest. There have been important new developments in each of the known gold-rich areas: Westland, Otago and Coromandel and exploration for gold in these areas and in previously unprospected regions has reached unprecedented levels. In Westland over 140 gold processing plants are each producing between two and six ounces a day from low-grade placers. A major gold dredging operation will soon be producing over a tonne of gold annually and other new dredges are proposed. There are still vast reserves of gold-bearing gravels in Westland and prospecting is continuing to reveal new resources. In the Reefton area there is renewed interest in gold-bearing quartz reefs which were the source of over a million ounces of gold between 1900 and 1951. New large opencast reserves are now defined.

Jan 1, 1988

By T. J. Fenner

Research conducted in South African mines has demonstrated the benefit of ground penetrating radar for the detection of geologic features and hazards. This is crucial for safety and production considerations in underground mines that are as much as 4 kilometers deep. This paper describes a new ground penetrating radar system designed specifically for high quality data acquisition, in the harsh conditions of deep underground environments, for use by operators with minimal geophysical experience. Design criteria included automated functions, intrinsic safety, light weight and minimal power requirements. Data is processed on the ground surface by geoscientists using a PC.

Jan 1, 1994

By Brian P. Canning

Ion exchange resin processes are receiving renewed attention in the mining industry for recovery;, of metals from solution. This interest has been inspired by the development of continuous countercurrent ion; exchange systems (CCIX) which are of much lower cost than the original, fixed bed contactor processes. With the countercurrent systems and new developments to process or upgrade the eluate product, ion exchange can now compete successfully with solvent extraction for treatment of uranium ores. The low concentration of U308 obtained in the CCIX strong eluate is generally upgraded by solvent extraction methods in sulfuric acid systems. Resin loadings of up to 120 grams per liter of U308, however, have been produced experimentally by recycling of eluate (HIM-IX process) and further developments may be expected in the near future. New developments in resin technology are bringing forth products of greater strength, loading capacity, selectivity and density. Densities up, to 1.35 spgr have been claimed by some suppliers. The process is not a new one and has taken years to advance to the present state of development. The earliest system to gain widespread acceptance was the resin-in-pulp system applied to uranium recovery. Ion exchange, however, later lost acceptance in favor of solvent extraction in the 1960's due to problems in resin degradation, resin contamination and resin-pulp separation, in addition to the development of improved solvent extraction reagents and techniques. The resin-in-pulp system continues to have application on high clay ores and has advanced in design. A number of other continuous ion exchange systems were also tried but never gained continued acceptance. In the current resurgence period the CCIX systems to gain acceptance were the Utah and Chem-Sep (Higgins Loop) systems. These processes are relatively simple in concept although require sophisticated controls. Fixed bed columns have also been designed into multistage systems in countercurrent operation but are not discussed in this paper. These systems remain competitive today for many applications. The most recent advancements however have been in the multistage contactors from,, which three are in current acceptance. These are the Himsley, Porter, and NIM systems. All industrial applications of these systems are relatively new, although pilot plant and in-plant development has been in progress over the last decade. Fur36ther developments should be expected in the near future.

Jan 1, 1979

By H. R. Green

The design of slurry launders has usually been based on strictly empirical concepts. An examination of the most common procedures reveals that they do not account for many of the variables that are recognized as Significant for slurry transport. These may include flow rate, volume concentration of solids, solids specific gravity, solids size distribution particle shape, launder geometry, and roughness of the wetted surface. It was decided to develop a design procedure, which would accomplish two things: First: Take into consideration most of the known significant variables and systematize the procedure to assure consistent results. Second: Provide a rational basis for examining and utilizing operating data to refine and improve the system. To accomplish this, it was necessary to develop a basic design concept. This concept has been developed through a complex development history, and yet still appears workable and technically sound. That concept may be outlined as follows: First: The solids transport velocity is the fundamental basis for slurry launder design. Second: The stream configuration, hence the launder size, is integrated with the solids transport velocity so that the actual stream velocity exceeds the solids transport velocity. Third: The launder slope is that which will achieve the required actual stream velocity. It was originally planned to utilize a series of charts and nomographs for the design procedure. A nomograph, based on data given in Taggart's Handbook of Mineral Dressing (1), was developed to determine the solids transport velocity. The velocity thus determined was used with Manning charts to determine the launder slope .and configuration as though the fluid were water. It was planned to utilize a "slope adjustment factor" to increase the slope to compensate for the apparent viscosity of the slurry. All attempts to develop a suitable correction factor failed. This failure was principally due to the complex relationship of viscosity to the required slope. It was then decided to revise the entire approach. Specifically, the present procedure is based on the Darcy-Weisbach flow equation, which is rationally preferable to the Manning equation. The Camp (2) equation is used for the solids transport velocity. The necessity of reference to the Moody curves for the Darcy friction factor is avoided by using the Colebrook and White (3) equation. The resulting mathematics require iterative solutions for several of the unknowns.

Jan 1, 1978

By M. G. Karfakis

Grouting has been used in underground mining for more than twenty years. Chemical grouting is often used as a remedial measure when the implemented ground control program is unable to completely prevent structural failures or when there is a need for preventing a structural member from unraveling. Utilization of the polyurethane grout currently being used is restricted by its limited range of physical and mechanical properties that restrict its utilization. To overcome some of the drawbacks of polyurethane, research has been conducted on a newly developed polyester based grout. The polyester resin, identified by Sandvik as StrataGrip, provides a number of features, including variable gel times and much reduced chemical hazard. Equally important are the mechanical properties of the product. The strength and deformability of any chemical grout must be compatible with the intended purpose of grouting and the expected deformation of the rock that is to be grouted. Assessment of the mechanical properties of polyester grout is the focus of this work. Field experiences and laboratory research have defined the properties of an effective grouting material. Experimental results indicate that the polyester grout meets or exceeds the recommended properties for many injection applications. Furthermore, the results suggest that the ability to adjust mechanical properties via resin formulation has the potential to expand the applicability of chemical grouting in ground control.

Jan 1, 1997

By Frank E. Kottlowski

Widespread high-calcium (HC) limestones in New Mexico and adjoining areas, are low in magnesium, but some units include shale interbeds that would be deleterious for usage in sulfur removal. In southwest New Mexico, southeast Arizona, and adjoining parts of Mexico, limestones in the thick Mississippian Escabrosa, Pennsylvanian-Permian Horquilla, and Cretaceous U-Bar units are HC as are strata in the Mississippian Lake Valley, Pennsylvanian formations, Permian Hueco, and parts of the Permian Capitan Limestone of south-central and southeast New Mexico and west Texas. In north-central and central New Mexico, many limestones in the Pennsylvanian Madera Formation are HC as are some of the Cenozoic travertines. In northwest New Mexico, where the present-day mine-mouth coal- fired power plants occur, there are no HC limestones, but to the north in southwest Colorado some beds of the Mississippian Leadville Limestone and Pennsylvanian Hermosa Formations are HC. HC limestones considered contain at least 95 percent calcium carbonate and less than 3 to 5 percent magnesium carbonate. Limits for other impurities are alumina, 1 percent; silica, 2 percent; sulfur 0.05 percent; phosphorous, 0.02 percent; and iron oxide, about 1 percent. Chemical and physical requirements differ slightly depending upon the ultimate use.

Jan 1, 1995

By Moussa Wone, William Levy, Christopher Caruso, Zachary Spera, Thomas Hennings, Richard Stacy Kinchen, PE Joel Kantola

"Owners constructing new combined sewer overflow (CSO) systems increasingly seek to have project design lives of 100 or more years in response to the growing size, complexity, and cost to construct and operate these systems. However, a codified and universally accepted approach to achieving this goal in the United States does not currently exist since service life prediction is a relatively new technical field. This paper discusses how the 100-year design life requirement was met for the design of tunnels, drop shafts, and diversion structures in the DC Clean Rivers Program (DCCRP). The authors identify some commonly referenced publications, present the testing framework used by the program manager to characterize the CSOs, review the design criteria used to guide the 100-year design life development, and establish guidelines to be considered by program managers and designers when implementing similar extended design life requirements in other CSO control programs.INTRODUCTIONLike many older cities in the United States, the sewer system in the District of Columbia consists of both combined sewers and separate sanitary sewers. When the capacity of a combined sewer is exceeded during storm events, the excess flow, which is a mixture of sewage and storm water runoff, is discharged to the District’s receiving water bodies (Anacostia River, Potomac River, and Rock Creek) and tributaries through outfall structures. This excess discharge during storm events is called a combined sewer overflow or CSO. A total of 53 CSO outfalls for the combined sewer system are listed in DC Water’s National Pollutant Discharge Elimination System (NPDES) Permit issued by the U.S. Environmental Protection Agency (EPA). The DC Clean Rivers Program (DCCRP) will reduce the number of CSO outfalls into the Potomac and Anacostia Rivers and decrease flooding in DC neighborhoods during extreme rain events by capturing, storing, and conveying diverted CSOs to the Blue Plains Advanced Wastewater Treatment Plant."

Jan 1, 2016

By J. J. Krizek, A. H. Ditto

INTRODUCTION The Carr Fork property is situated in the Bingham Mining District located on the east slope of the Oquirrh Mountain range in Utah. The mine is adjacent to and lies west of Kennecott's Bingham Pit some 25 miles southwest of Salt Lake City. The Bingham Mining District contains one of the largest copper reserves on North America. Mineralization is associated with the Bingham stock which intruded through some 16,000 feet of sedimentary formations. Mineralization and a1teration zoning was developed radially from the Bingham stock with lower grade disseminated copper mineralization centrally located in the stock and adjoining quartzites. In addition, several garnetized limestone beds abutting the stock were also well mineralized. These skarns will be Carr Fork's initial mining target. Of the several limestone beds, only two, the Yampa and the Highland Boy have significant commercial interest at present. These beds which are 50 feet to 150 feet thick and are separated by 200 to 400 feet of quartzite were highly folded, thrusted and faulted, resulting in a dip variance from 20" to vertical. The predominant dip, however, is between 20" and 45" from horizontal. Quartzites surrounding the limestone beds were subjected to the same degree of tectonic activity with resultant intense fracturing and stress relief. The limestone beds which have a higher elastic modulus and which also experienced fracture healing during mineralization appear to have greater competency and strength than the quartzites. Four shafts nominally 3500 feet deep will provide access to the mine which will be a highly mechanized trackless operation, designed to produce 14,000 tons per hoisting day. First production is scheduled for the last quarter of 1979.

Jan 1, 1977

By Stephen Utter

One function of mining is to supply oil shale of the required grade and characteristics to surface retorts. The mining methods must he safe, efficient, and environmentally acceptable. Although the Bureau of Mines no longer conducts research on methods of mining fossil fuels, including oil shale, its many years of activity in that field resulted in a significant body of findings. This article summarizes some of these findings, with respect to oil shale mining. The large areal extent of Green River formation oil shales and the diversity of geologic, hydrologic, topographic, and other conditions, preclude the use of any one single mining and waste management technique. Instead, in most instances, methods and equipment will be chosen to meet site-specific conditions. Such methods include conventional surface mining (open-pit and strip), underground mining (room-and-pillar, sublevel stoping, caving) and in situ extraction (true in situ from surface drill holes and modified in situ from underground retorts containing rubblized oil shale). Combination or hybrid systems may prove suitable. Both surface and underground backfilling of spent shale waste may be practiced. Tremendous amounts of oil shale must be mined, processed, and the waste shale properly disposed of in order to meet projected industry production goals. For example, about 1.4 tons of oil shale averaging 117 L of shale oil per ton are required to produce one bbl of oil. A plant with a daily production of 8 dam' (50 000 bbl) of oil would thus require some 68 kt of raw shale daily. This is more than the average daily production from any underground mining operation.

Jan 1, 1981

By J. A. Zimmer, M. S. Hillis, D. Moredock, J. A. Organiscak, A. B. Cecala

Enclosed cabs have been used on surface mining equipment for many years to protect equipment operators from health and safety hazards. The surface mining and quarrying process is a highly mechanized process that generates large quantities of respirable dust. Due to economic factors, more older mining equipment is being used today than in years past. With this older equipment, it is common to observe deterioration of many components on the enclosed cabs, which greatly reduce their protection effectiveness. NIOSH has performed a number of different field studies, as well as a comprehensive laboratory study, evaluating various factors and parameters regarding enclosed cabs. NIOSH has recently completed a cooperative research effort to evaluate the effectiveness of a newly designed unidirectional powered precleaner, filter and pressurizer that brings clean filtered air in at the roof of the cab and extracts all recirculated air near the floor. This research effort provided another example of the enhancement in air quality that can be achieved in an enclosed cab from the implementation of an improved filtration system and by establishing positive pressurization from increased intake air volume and sealing the cab. This testing showed a significant reduction in respirable dust levels in the enclosed cab when comparing baseline versus post-testing results. Since dust levels were similar near the roof and floor of the cab during post-testing, the unidirectional flow pattern did not appear to significantly improve the performance over the conventional design in this study.

Jan 1, 2009

By Russell C. Drew

The United States has long been recognized for its ability to marshall the many tools of its scientists and engineers to meet national threats or crises. Two major World Wars, the Dust Bowl, the Soviet Missile threat, Sputnik, and more recently the Energy Crisis have stimulated military weapons development, massive land reclamation and water management programs, NASA, and the Space Program, Project Independence, and soon a new agency, the Energy Research and Development Administration. While our record of successful responses to these major national concerns lends support to the expectation that we will succeed in dealing with the current energy problem and potential future crises as well, the crisis mode of response is becoming increasingly wasteful of funds and human and natural resources. This waste, while always of a concern, is a more important factor than previously because of the accelerating pace at which the world has been shrinking, relatively, in comparison to its human population and that population's increasing demand for resources, both renewable and nonrenewable. If present growth patterns continue, in the year 2000 there will be two people to feed, clothe, house, and satisfy for every one person that existed in 1970. On a finite planet, with finite land areas, limited resources, and only partial understanding of the means by which future problems can be addressed, one of the major threats to mankind will be scarcity and one of our major challenges will be better management of our resources. The challenge will be to guide Federal investments in R&D that are of sufficient magnitude and in the proper

Jan 1, 1974

By P. C. O. Chukabarah

Many aerodynamic and thermodynamic properties, such as temperature, pressure, velocity and density vary widely, and in random spatial and temporal manner for a given underground mine environment. Such variabilities are seldom evaluated statistically, even though the relevant theories and principles for such an approach are both available and feasible. The main purpose of this paper was to introduce the new methodology of applying aerostatistics to the analysis of multiple fan system in mine aerology and/or ventilation. Pertinent data were obtained from a small multilevel coal mine. Results proved and confirmed that aerostatistical methodologies are computationally more efficient, grounded in solid engineering statistical theories, and can be used to analyze networked parameters in mine environmental engineering.

Jan 1, 1994

By N. Dahmen

The Robbins Mobile miner has been in development for more than ten years. Two machines have been trialed in mining environments. While day to day performance to date has fallen short of the levels anticipated, instantaneous performance has been impressive for given rock conditions and continues to encourage further development. The Pasminco mobile miner has been committed for a 1.8km main decline extension at Broken Hill. M.I.M. Holdings, parent company of Mount Isa Mines, owner of the first mobile miner, are considering a new machine for McArthur River. Robbins, Pasminco, and The Centre for Mining Technology and Construction have, joined forces to accelerate development of .mechanical rock cutting techniques in general, and of the Mobile Miner in particular.

Jan 1, 1995

By M. E. Buzon, M. E. Gunter, B. D. McNamee

A Google search on talc asbestos yields more than 500,000 hits due to the growing number of civil lawsuits in this area. Historically, the litigation was centered on amphibole-containing industrial talc. There was no debate these talcs contained amphiboles, but the issue was the definition of asbestos and whether the amphiboles had an asbestiform habit. Ultramafic-hosted talcs, however, are formed in such a way as to not favor the formation of amphiboles in the talc, but they can occur in the surrounding black-wall. In these deposits, the serpentinite host rock is in direct contact with the talc, therefore, allegations can be made that non-asbestiform amphiboles or non-regulated serpentine group minerals can occur in the final products. We analyzed talcs from both metamorphosed carbonate- and ultramafic-hosted talc deposits using polarized light microscopy (PLM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), electron microprobe (EPMA) with wavelengthdispersive spectroscopy (WDS), transmission electron microscopy (TEM) with EDS, and powder X-ray diffraction (XRD). Compositions of minerals determined by EDS alone are not sufficient to confidently identify asbestos, despite common practices by some researchers. We emphasize, using both historical samples, and analyses of currently contested minerals, the importance of determining both the structure and composition of a mineral, as well as defining its morphology, before concluding whether it is asbestos.

Jan 1, 2018

By James M. Barker, George S. Austin

Stone, one of the oldest building materials, today remains a well-established material throughout the construction industry. The use of natural stone is much less prevalent now than in the past. It is still widely considered to be the most aesthetically pleasing, prestigious, and durable building material. New and re-opened quarries are coming onstream to meet increased demand related to new building technology and increased residential use of stone. CLASSIFICATION No classification can completely eliminate overlap between dimension stone, aggregate, and decorative stone because most stone is multi-purpose. Many used for decorative purposes are not produced specifically for that end use. Rock otherwise considered waste in dimension stone or aggregate quarries can be decorative stone coproducts (Fig. 1). Many uses require a compromise between decorative and structural qualities (Bowles, 1992, written commu¬nication). Shipley (1945) used decorative stone interchangeably with or¬namental stone. Gary et al. (1972) defined decorative stone as that used for architectural decoration, such as mantels, columns, and store fronts, but added that it is sometimes set with silver or gold in jewelry as curio stones. Bates and Jackson (1987) also restricted decorative stone to that used for architectural decoration. Meanings of otherwise identical terms used in the stone industry differ be¬tween geologists, engineers, and quarriers. They often carry a much broader meaning for quarriers and engineers compared to their very specific use by geologists (Makens et al., 1972). Decorative stone, including ornamental stone, is more broadly defined by geologists as any stone used primarily for its color, texture, and general appearance. It is not used primarily for its strength or durability, such as construction stone, or in specific sizes, such as dimension stone. The decorative stone industry uses a much wider range of stone types compared to stone that is dimensioned. Decorative stone usually serves some structural pur¬pose, but is not load-bearing to any great extent. Weak or costly stones serve in decorative, not structural, applications. STATISTICS AND END USES Decorative and dimension stone data are difficult to separate because the US Bureau of Mines keeps statistics only on dimension stone and crushed stone. The value of domestic dimension stone production in 1990, which includes some decorative stone, was about $210 million compared to imports of about $524 million and exports of about $35 million. Production was 1 080 t of which at least one-third was for decorative uses (Taylor, 1992). The principal uses are rough blocks in building construction (23%) and monu¬ments (18%); the remainder is used as ashlar (18%), curbing (12%), and miscellaneous (29%). Major rock types are granite (50%), limestone (30%), sandstone (10%), slate (3%), marble (2%), and other (5%) (Harben, 1990). Crushed stone valued at $5.6 billion was produced in the United States in 1990 by 1700 companies operating 3400 active quarries in 48 states (Tepordei, 1991). About 52% is used in con¬struction, 9% in cement and lime manufacturing, 2% in agricul¬ture, 2% in industrial uses, and 35% for unspecified uses including decorative aggregate. Limestone and dolomite comprise about 71%, granite 14%, and traprock 8% of the stone crushed in the United States. The remaining 7% are, in descending quantity, sandstone, quartzite, miscellaneous rock, marble, shell, calcareous marl, volcanic cinder and scoria, and slate. The basic types of decorative stone are: rough stone, aggregate, cut or dressed stone, and manmade stone [(Table 1)]. Rough Stone Rough stone is used as it is found in nature with very limited processing such as minor hand shaping, edge fitting, and size or quality sorting (Perath, 1992, written communication). This stone type is often marketed locally in relatively small tonnages and includes fieldstone and flagstone. The primary end uses of rough stone are landscaping, edging, paving, or large individual stone landscape or interior accents [(Fig. 2)]. Fieldstone: Fieldstone is picked up or pried out of the ground (gleaned) without extensive quarrying and includes garden or large landscaping boulders (Austin et al., 1990, Hansen, 1969). Boulders and cobbles may be split or roughly trimmed for use in rubble walls and veneers, both interior and exterior. Popular fieldstone rock types include sandstone, basalt, limestone, gneiss, schist, quartzite, and granite, but many others are suitable. Much fieldstone is col¬lected by individuals or small companies because the industry is labor intensive and markets are small. The stone may be sold locally in small quantities from the back of vehicles (Austin et al., 1990). Fieldstone includes many rock types, sizes, and shapes with the only common denominator that it must be set by hand and be durable (Power, 1992, written communication). Moss Rock. Moss rock is fieldstone partially covered by algae, mosses, lichens, and fungi that give the rock an aged and variegated patina (Austin et al., 1990). The plants are supported by moisture and nutrients in the stone. Moss rock is used for landscaping, walls, and fireplaces. Although almost any durable rock can be a moss rock, most are slabby or rounded sandstone and limestone (Fig. 3). Flagstone: Flagstone or flagging consist of thin irregular slabs used for paving, walkways, and wall veneers. Random-shaped flagging is produced widely in the United States. Suitable stone

Jan 1, 1994