INTRODUCTIONIn the chapter on characteristics of the industrial minerals sector, abroad definition of industrial minerals and rocks is discussedadefinition that must embrace solids, liquids, gases, minerals, rocks,gems, glasses, wastes, and some manufactured productseach cat-egory with its own range of uses. Clearly, industrial minerals androcks do their utmost to defy simple definition and are linked asclosely by their differences as by their similarities.

To bring some order to this disparate field, a classification sys-tem is needed to highlight the commonalities and contrasts in astructured way. Any robust classification must address the needs ofa wide range of potential users that may include (but is not limitedto) academics, industrial geologists, industrial raw material users,specifiers, product formulators, technologists, engineers, managers,and financiers and investors. Given their different priorities, focusof attention, and backgrounds, it is not surprising that no singleapproach is universally adopted.

CLASSIFICATION SCHEMESA range of classifications based on a variety of commodity criteriahas been used over the past 50 years or more as tools for under-standing the geological context, market uses, defining properties,economic contribution, and statistical significance of industrialminerals and rocks. Each approach has its strengths and weak-

ClassificaIndustrial Miner

Kip Jef7

nesses, and any durable scheme in such a dynamic industrial sectorwill inevitably present only part of the picture. Bates (1975) exam-ined a number of these schemes, and more extensive comparisonshave been undertaken by Kuzvart (1984), Noetstaller (1988), andSmith (1999). All of these were drawn on extensively for thisreview.

BerzelianThe world of systematic mineralogy has a number of classificationsystems that have also been applied to industrial minerals. Mostmuseum mineral collections are catalogued by the Berzelian classi-fication system, which is based on elements, ions, ionic groups, andcompounds such as halides, oxides, carbonates, and silicates,among others. This system was used in early accounts of the non-metallics (such as in Merrill 1904) and also hydrocarbons, but notindustrial rocks other than some siliceous and calcareous examplesunder silica and calcium carbonate, respectively. The classificationdid not cover waste materials, brines, or most manufactured prod-ucts because many of these were yet to be recognized as importantraw materials or products.

AlphabeticThe simplest approach, and certainly the most intuitive and accessi-ble for those from outside the subject seeking commodity-specificinformation, is nothing more complex than the alphabetical listingof commodities. This has been adopted for systematic commodityreviews in earlier editions of this book (e.g., Lefond 1975; Carr1994). Indeed, as noted by Harben and Bates (1984), the alphabetictreatment neatly sidesteps the vexatious matter of classification.

This edition in part adopts the same approach as it lends itselfto simple encyclopedic interrogation once a mineral or commodityis identified. Approximately 60 commodities are typically includedin such a listing, but these are always under review. This simplisticcompositional approach works reasonably well for industrial min-erals but requires a degree of clarification and consistency becausesubdivisions are often necessary. For example, clays can be dividedinto bentonites, which can in turn be divided into sodium or cal-cium smectites. Nomenclature for industrial rocks and other rawmaterials can also be variable; for example, brick clay, commonclay, structural clay, and heavy clay are all common pseudonymsand are based more on application than composition.

Unfortunately, the alphabetic approach to classification

tion ofals and Rocks

freyobscures many important links between commodities, includingsimilar properties they possess, geological processes that led to theirformation, or applications in which they are used. For this reason,the alphabetic classification employed in this edition is supple-mented by important reviews of major markets and uses for indus-trial minerals and rocks. Although this approach may suit thoseusing a book format, other forms of classification have been devel-oped that may be more useful for the consumer or the geologist.

Geological ProcessesFrom the geologists perspective, there is much to be gained by try-ing to place a genetic classification on such a wide variety of materi-als (Bates 1960; Harben and Bates 1984). There are well-definedcategories of geological processes responsible for the formation ofall minerals and rocks, and industrial minerals and rocks encompassthe complete spectrum. Such a classification parallels standard geo-logical understanding and has exploration relevance because a com-modity may be found again in other places where these processes

ra

vagrsidominate. Because particular geological processes often result in arange of similar products, there is also some natural grouping ofphysical properties, although this is far from uniform.

The dominant divisions have been igneous, sedimentary,metamorphic, and surficially altered minerals and rocks (Harbenand Bates 1984). Igneous subdivisions were intrusive, extrusive,pegmatitic, and hydrothermal; sedimentary was divided into clastic,biogenic, and chemical. Because this is principally a geological cat-egorization, waste and processed materials were not specificallyaddressed. In their follow-up account of world deposits (and aftermuch deliberation; P. Harben, personal communication), the sameauthors reverted to an alphabetic arrangement of commodities,allowing very different deposit types to be discussed under individ-ual commodity headings (Harben and Bates 1990).

Lorenz (1991) produced a more detailed tabulation of geolog-ical origins for industrial minerals deposits, along with a similaranalysis of deposit sizes and many other economic, technical, andend-use parameters.

Tectonic ModelsAlthough mainly developed as exploration models, these block dia-grams have, in effect, produced a tectonic classification of deposit

1994). They are therefore a development of the geological processclassifications and have the major advantage of allowing analysis ofthe potential spatial, as well as geological, relationship between dif-ferent industrial minerals. This makes the approach an ideal one forindustrial minerals exploration and parallels the earlier work under-taken for metal deposits (e.g., Mitchell and Garson 1981; Sawkins1984).Important PropertiesAs the phrase industrial minerals and rocks implies, each com-modity has some commercially significant composition or propertyon which its use is based. Kline (1970) devised a simple twofolddivision: chemical minerals, where their main purpose is as thesource of important elements (e.g. industrial minerals and rocksused in the fertilizer, chemical, ceramics, and metallurgical indus-tries); and physical minerals, where the minerals do not signifi-cantly change in composition during use. Important features of thislatter group, which include many construction materials, abrasives,foundry supplies, gems, and fillers, would be their physical proper-ties such as particle-size distribution, brightness, and surface area.

These considerations have become central to many later clas-sifications but usually as one part of a more complex set of classifi-

Source: Anon. 1994.Figure 1. Industrial mineral deposits found in active continental margins

Beach SandsOlivine

OceanicTrench

Hydrothermal Alteration of VolcanicsBentonite, Kaolin

Ophiolite:Ultrabasic Rocks

Chromite, Dunite, Serpentinite,Magnesite

Ophiolite:Pillow Lavas and SedimentsOchre, Umber8 Industrial Mine

Air Fall Ash (Fine)Pumicite, Pozzolana

Air Fall Lapilli(Coarse)Pumice

Lateral Cinder ConeScoria

Runoff High in Dissolved Silicon

Caldera SubsidenceLake SedimentsBentonite, Zeolite,Diatomite

Rhyolite DomePerlite LaAg

Dimen

FummarolesSulfurtypes for particular commodities (Figure 1; Anon. 1994; Highleyls and Rocks

Flowegateon Stone

Ash Flow TuffPumice, Dimension Stone,

Aggregate

Fore ArcBasin Fore Arc

Alluvial FansAggregatecation criteria.

tClassification of Indus

End-Use ClassificationsIt is a common saying in the industrial minerals and rocks sector thatexploration begins with markets (Coope 1982). This highlights theessential importance of understanding that the mineral or rock hasvalue only if there is a customer willing and able to pay for it. Min-erals are, however, capable of being utilized in many different enduses; limestone, for example, can provide more than 100 separateproducts that are used in very different applications. Equally, someconsuming industries require a suite of different industrial minerals,each of which alone would not meet the needs of the manufacturingprocess. For these reasons, many classifications have concentratedon either the end uses for minerals and relationships between them,or combined end uses with other important parameters of the indus-trial minerals and rocks industry.

Following the work of Bates (1959) and Wright and Burnett(1962), Fisher (1969) conducted a detailed analysis and defined sixmajor end-use groupings that were characterized by variation inunit value, production volume, and associated parameters:

1. Bulk construction and building materials2. Bulk ceramic raw material (in addition to lime and diversified

industry raw materials or products)3. Specialty building products and principal refractories4. Major industrial chemicals and fertilizer raw materials5. Industrial minerals and rocks6. Specialty-grade and precious minerals and rocks

For each group, Fisher also presented a series of graphs showing thetypical levels of capital and plant cost, place value, resource spread,enrichment ratios, and fiscal treatment, based on deposits and compa-nies in the United States. Although the groupings are defined on enduses, this represents one of the earliest and most rigorous attempts ata multifaceted classification for industrial minerals and rocks.

In a major review of nonmetallic mineral deposit assessmentcriteria, Lorenz (1991) produced a detailed tabulation of commodityuses in some 38 products or intermediate products. Highley (1994)adopted a more straightforward graphical attempt to illustrate impor-tant sectors with a hierarchical chart of major end users. Chang(2002) also produced an account of the industrial processes and enduses for the main industrial minerals and rocks and noted that theycould be allocated into 16 groupings based on their function or finalproduct.

Although not an attempt at a rigorous classification, the enduses for ground (filler and extender) minerals are examined from aformulators viewpoint in Ciullo (1996). Although this representsonly a section of both consuming industries and industrial mineralsand rocks, it provides a useful way of examining the diverse rolesthat different minerals play in products and their ability to substi-tute for each other.

EconomicAs part of their objective to inform Californians about their statesgeology, mineral deposits, and general usefulness of minerals androcks, Wright and Burnett (1962) proposed a threefold commer-cial classification of industrial minerals and rocks. Based on unitprice and production volumes, the groups were

1. Low pricelarge volume: materials used in construction suchas aggregates, gypsum, and common clay

2. High pricehigh volume: borates, potash, and salt3. High pricelow volume: barite, kyanite, beryl, mica, and talcEach group was also identified as having a number of common fea-tures in terms of their deposit size, distribution, location, miningmethods, and treatment.rial Minerals and Rocks 9

Bates (1969) developed his own twofold subdivision based onan analysis of similar high and low unit-value commodities. Thisalso involved examining the bulk, place value, imports and exports,and distribution and geological or processing complexity that typi-fied each group. He concluded that because most industrial miner-als fell into the high unit-value group, while industrial rocks mainlyfell in the low unit-value group, these should form the basis of asimple classification. In this scheme, rock salt is regarded as a rock,while potash a minerala slightly arbitrary attribution that fits bet-ter with the typical characteristics of other commodities within eachgroup (Table 1).

From a systematic economic perspective, Noetstaller (1988)produced a highly illuminating analysis of the industrial mineralsand rocks sector in his report for the World Bank. Although againnot principally for classification purposes, the lists and graphs pro-duced for ranking and economic comparisons offer much insightinto the ranges and clustering of industrial minerals and rocks com-modities under many economic, trade, technical, and even geologi-

Table 1. Industrial minerals and rocks classification based on end use and genetic subdivision

Aspect Group 1 Group 2

Bulk Large Small

Unit value Low High

Place value High Low

Imports and exports Few Many

Distribution Widespread Restricted

Geology Simple Complex

Processing Simple Complex

Industrial Rocks Industrial Minerals

Igneous Rocks Igneous Minerals

Basalt and diabase Beryl

Granite Feldspar

Perlite Lithium minerals

Pumice and pumicite

Mica

Nepheline syenite

Metamorphic Rocks Vein and Replacement Minerals

Marble Barite

Slate Fluorspar

Magnesite

Sedimentary Rocks Quartz crystal

Clay Metamorphic Minerals

Gypsum Asbestos

Limestone and dolomite

Graphite

Talc

Phosphate rock Vermiculite

Salt Sedimentary Minerals and Sulfur

Sand and gravel Borates

Sandstone Diamond

Diatomite

Nitrates

Potash minerals

Sodium minerals

Sulfur

Adapted from Bates 1969.cal parameters. Examples include commodity lists by unit value,concentration of production in certain countries, the proportion ofeach commoditys production that is traded internationally, and a

r10 Industrial Mine

contrast of commodity production and consumption between thedeveloping and developed world. An update of this World Bankreport would be of great service to the industry.

Hybrid and Combined MethodsBates (1960, 1969) produced a combined end-use and genetic clas-sification incorporating a simple initial division into industrialrocks or industrial minerals, with duplicated geological subdivi-sions denoting the origin within each (see Table 1).

To attempt to relate geological and economic factors, Dunn(1973) developed a matrix classification in the form of a chart withone axis as uses and processes, and the other as rock types and min-erals. The matrix incorporates the split by importance of eitherphysical or chemical property (similar to Kline 1970), with 23 gen-eral end-use subdivisions, against which are indicated specificrocks or minerals used and their geological origins (similar to Bates1969). The main strength of this chart was to visually highlight theversatility of some rock or mineral products, the geological envi-ronments that provided a range of economically interesting prod-ucts, and the end uses that exploit many alternative orcomplementary mineral raw materials.

Kuzvart (1984) undertook a thorough comparison of differentprinciples on which classifications have been constructed. Hefavored a classification system based on a combination of genetic,end-use, and economic aspects of industrial minerals. This wasachieved despite the observation that an understanding of the gene-sis, end uses, and economics of deposits develops continually,requiring frequent revision of a classification based on these fac-tors. He did, however, organize his work to encompass the twofoldeconomic classification of Bates (1969), with an alphabetic subdi-vision of commodities supplemented by separate chapters address-ing genetic, prospecting, and technological factors.

As a tool to assist in teaching about industrial minerals androcks, Smith (1999) developed a classification that defined sevengroups of commodities based on the relative importance of physicaland chemical applications or a combination of the two. The classifi-cation is constructed using a matrix of commodities and uses thatare grouped according to application. Clustering of commoditiesreveals the following groupings:

1. Principal abrasivesdiamond, alumina, garnet, and pumice2. Principal refractoriespyrophyllite, sillimanite group, magne-

site, and graphite3. Principal fillerswollastonite, titanium minerals, mica, barite,

and iron oxide4. Principal physical and chemical mineralsfeldspar and zeolite5. Mixed-application physical mineralssilica, perlite, clay, and

talc6. Principal chemical mineralsphosphate, salt, and sulfur7. Mixed-application physical and chemical mineralsolivine,

chromite, fluorspar, gypsum, and limestoneThe matrix was also supplemented by a schematic representa-

tion of the groupings in the form of a set of intersecting circles.

Other ClassificationsIndustrial minerals are included and subdivided in all manner ofother classifications, from depletion allowances to tax rates, underimport duties and Bureau of Statistics classifications, and in a mul-titude of economic categories. These generally do little to illumi-nate industrial minerals and rocks as a group and will not be

considered in any further detail here.als and Rocks

LIMITATION OF THESE APPROACHESTo exploit an industrial mineral deposit successfully, all factors needto be considered, including deposit location, quality, processingamenability, other essential raw materials, power, infrastructure,human resources, competition, marketing, packaging, transporta-tion, technical support, prices, and contractual agreements. It istherefore unreasonable to expect any classification scheme toaddress the full range of factors that are intrinsic to or affect eachcommodity or grouping. The industry is dynamic; commodities riseand fall as new applications develop or cheaper and better alterna-tives surface. Technological advances improve bottom-line perfor-mance. A classification system must adapt to these changes. Arobust classification system must address the geological, composi-tional, economic, and end-use properties of each commodity.

REFERENCESAnon. 1994. Minerals for Development. British Geological Survey

Technical Report WG/94/13. Nottingham: Natural EnvironmentResearch Council (NERC).

Bates, R.L. 1959. Classification of the nonmetallics. EconomicGeology 1(54):248253.

. 1960. Classification. Pages 1519 in Geology of theIndustrial Rocks and Minerals. 1st edition. New York: Harper.

. 1969. Geology of Industrial Rocks and Minerals. NewYork: Dover Publications.

. 1975. Introduction. Pages 37 in Industrial Minerals andRocks. 4th edition. Edited by S.J. Lefond. New York: AIME.

Carr, D.D., editor. 1994. Industrial Minerals and Rocks. 6th edition.Littleton, CO: SME.

Chang, L.L.Y. 2002. Industrial Mineralogy: Materials, Processesand Uses. Upper Saddle River, NJ: Prentice-Hall.

Ciullo, P.A., editor. 1996. Industrial Minerals and Their Uses.Westwood, NJ: Noyes Publications.

Coope, B.M. 1982. Industrial mineralsexploration begins withmarkets. Transactions of the Institution of Mining andMetallurgy 91:B8B10.

Dunn, J.R. 1973. A matrix classification for industrial minerals androcks. Pages 185189 in Proceedings of the 8th Forum on theGeology of Industrial Minerals. Public Information Circular 5.Iowa Geological Survey.

Fisher, W.L. 1969. The nonmetallic industrial minerals: Examples ofdiversity and quantity. Mining Congress Journal 55(2):120126.

Harben, P.W., and R.L. Bates. 1984. Geology of the Nonmetallics.New York: Metal Bulletin.

. 1990. Industrial Minerals: Geology and World Deposits.London: Metal Bulletin Plc.

Highley, D.E. 1994. The role of industrial minerals in theeconomics of developing countries. In Industrial Minerals inDeveloping Countries. Edited by S.J. Mathers and A.J.GNortholt. Association of Geoscientists for InternationalDevelopment (AGID) Report Series, Geosciences inInternational Development, No. 18. Nottingham: BritishGeological Survey/AGID.

Kline, C.H. 1970. Industrial minerals are big business. MiningEngineering 22(12):4648.

Kuzvart, M. 1984. Industrial Minerals and Rocks. Developments inEconomic Geology 18. Amsterdam: Elsevier.

Lefond, S.J., editor. 1975. Industrial Minerals and Rocks. 4thedition. New York: AIME.

Lorenz, W. 1991. Criteria for the assessment of non-metallic

mineral deposits. Geologishe Jahrbuch A127:299326.

Classification of Industrial Minerals and Rocks 11

Merrill, G.P. 1904. The non-metallic minerals: Their occurrencesand uses. New York: John Wiley & Sons.

Mitchell, A.H.G., and M.S. Garson. 1981. Mineral Deposits andGlobal Tectonic Settings. London: Academic Press.

Noetstaller, R. 1988. Industrial minerals: A technical review.Technical Paper No 76. Washington, DC: World Bank.

Sawkins, F.J. 1984. Mineral Deposits in Relation to PlateTectonics. Berlin: Springer-Verlag.

Smith, J.V. 1999. A classification scheme for industrial mineralsand rocks. Journal of Geoscience Education 47:438442.

Wright, L.A., and J.L. Burnett. 1962. The search for industrialminerals. Mineral Information Service, California Division ofMines and Geology 15(1):18.

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