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ratio) and if its composition and lattice matches that of an amphibote, that particle can be called ®asbestiform" amphibole, or simply, "asbestos". Consequently, all available data on the health hazards caused by the inhalation of asbestos fibers can be applied to acicular amphibole fragments, thus eliminating the need for the extensive job of determining the nature and the extent of the health effects of the actual particles, that is, the acicular amphibole fragments. On the other hand, the new definitions created serious problems, probably not forseen by the promoters of the new definitions. For example, jade became an asbestos in spite of the fact that jade is the toughest known natural substance [8]. One type of jade (nephrite) is mineralogically actinolite-tremolite, and according to the new definitions, it is an "asbestiform mineral" and its acicular fragments are "asbestos-like fibers". The other type of jade is jadeite, a pyroxene. Pyroxenes are similar to amphiboles as far as both are chain silicates and break into acicular fragments. The only major difference between these two groups of minerals, in terms of their qualifications for "asbestos", is that pyroxene is not "hydrated". Consequently, in terms of the new definitions jadeite is not an asbestos. However, one could argue whether the presence of OH is really necessary in the definition of asbestos.s At the same time the new definitions include many non-asbestiform mineral varieties in the rank of asbestos, they also exclude a number of other minerals, (e.g., non-hydrous silicates) which in fact may also crystallize occasionally in asbestiform habit. Most of these minerals are rare and are not known to constitute commercial deposits. Nevertheless, a mineralogical definition should not be tied to commercial criteria. The new definitions, of course, magnify the extent of the potential asbestos pollution problem by an exponential factor. If all amphiboles are "asbestiform" and their fragments are °'asbestos-like" then every state in the union has some asbestos in the soils, drifts, and bedrocks. Kryvial, Wood, and Barrett show [44, p. 13] the distribution of "high con- centration of asbestiform phases" of rocks in the continental United States. Only a few of the amphibole-bearing rocks included in that survey contain even a minor fraction of known, true asbestiform varieties of amphiboles. the new definitions are not only contrary to mineralogical traditions but are inadequate for crystal chemical descriptions. They also can lead to ambiguity and contradiction. For example, Kryvial, et al. in their monograph [44, p. 5] wish to exclude hornblende from the 11asbestiform" category of amphiboles; apparently because hornblende seldom crystallizes in asbestiform habit. However, the new definition of "asbestiform" does not allow them to use it in that sense, or to express the same concept in any other non-ambiguous way. They try to get around the problem by using the term fibrous in an ambiguous way by stating that hornblende is '°seldom seen in a fibrous form". Yet in page 3 of the paper they state that all amphiboles "fragment into fibers", whether they are products of an "acicular form of a fibrous crystal" (7) or not. They admit that at a microscopic scale the fragments of hornblende are no different from that of other amphiboles. Apparently, what they are trying to say is that fibrous is not always fibrous, but the new terminology does not allow them to distinguish between these two types. The proper mineralogical terminology can do that. Most mineralogists object to the misuse of the mineralogical terminology. Some mineralogists, however, have found themselves in situations where compromise was necessary and they used the new definition of fiber (>3:1 aspect ratio) and the term "fibrous" in an accordingly loose context [42,45,71], sometimes with comments on the disciplinary restric- tions of that terminology [11].e slt is not entirely impossible that the minute acicular crystals of jade may turn out to possess some asbestos properties. In that case minute fragments of jade could appropri- ately be called asbestiform fibers. sThe authors of [11] accept the new definition of fiber "in the context of studies of health hazards". 3 2063104805

The true background and character of mineralogical concepts and the seemingly complex definition of the asbestos-related mineralogical terminology can be best illuminated through a historical analysis of the relevant terms and expressions. That will be attempted in the following pages. Historical Review Asbestos 9n history. Asbestos is probably the most unique substance in the mineral kingdom. To begin with, it does not even look like a stone, but looks more like some organic wool or cotton. Good quality asbestos is more elastic than other minerals and its high tensile strength is unique. Asbestos is not only stronger than organic fibers but it is also more durable, is fireproof, and for all practical purposes, amphibole asbestos is chemically inert. The peculiar properties of asbestos have attracted the attention of man throughout history. In early times the use of asbestos was restricted either to the households of powerful and rich royalties or to special geographic areas. There are records that Egyptians, Greeks, Romans and even earlier civilizations had knowledge of asbestos and used it for special purposes. The Eqyptians sometimes used coarse asbestos cloth to protect the embalmed bodies of Pharaohs from the ravages of time. The Romans made cremation wrappings to collect the unspoiled ashes of emperors. The lamps of the Vestal Virgins were furnished asbestos wicks which lasted forever. There are also some questionable records that the Romans threw asbestos and other toxic substances in the river flowing through the besieged city of Auxium, in order to break the resistance of the defendants. According to legend, Charlemagne had an asbestos tablecloth which he threw in the fireplace after dinner for the purpose of cleansing it, to the amusement of his company (fig. 1). Figure 1. Ge Boot's (6] illustration of the fire-proof property and the making of asbestos cloth. As it can be expected, in addition to the practical uses there were some less logical and more mysterious applications of asbestos in early and in superstitious civilizations. In medieval times, for example, asbestos was used as a major ingredient in an ointment (fig. 2) intended to cure a number of diseases. Loosely translated De Boot's prescription reads: "Multiple application, miraculous asbestos ointment for juvenile tinea (head-fungus?) and shinbone (skin?) ulcer. Take 4 oz. asbestos, 12 oz. lead (oxide?), 2 oz. zinc oxide, and calcinate, thereupon pulverize into glass while adding vinegar, and agitate it daily for a month; after a month boil it for a quarter hour and let it cure until it becomes clear; thereafter add some vinegar, mix it with rose-petal oil until it becomes a homogeneous ointment: then go and smear it over the infant's head, to promote healing: for itches and shinbone ulcer smear it over the 4

affected area in the evening, for healing. The same mineral, mixed with aqua vitae and bamboo syrup, when applied in small quantities in the morning will sooth the pain of female white-menstruation (leukorrhea?), and will soon heal." Aa,a.. £t Amianta linimeutamadtrineampuerorum, 6!•s.r• & ad uleera tibiaru miraculoCum fit Cequenn mo- '"i^"" do. Accipiuntur Amiand une.quatuora plumbi uncix ta,mtizuncizdue,aculcinancur, deinde srmrsei. pulverifauinvitromaurantureumaeeco,acquo- tidicpermenCemmateriaagicamrfemoapo(tmen; fcm ebulliendaoR unius harm quadrante, ac quie- fcere fudtut, donec indarefcar. deinde illius ueti clariquandras, cumpari.quantirateolei roGcei. miCacmr,donec bona 6atunio Hnimentiforma: co innngiturceput pncrf tomtn ut eiro fanemc ad fea- bicm, & ulcera tibiarum refperi pucee unguntur, .rd.ln- donee Ganentur. Si laapis hie cum aqua vit.T, & Cae-t& :haro Colvatur,ac exigea portio mane quoridiemu-e f~tla licri albo monRruo laboranti decur,moc fanacur. mt,~a# Figure 2. De Boot's prescription for the miraculous asbestos ointment [6, p. 384-5]. The industrial revolution opened an era yielding rich rewards for imaginative inven- tions. Asbestos, as other unique minerals, did not escape attention and a large number of applications were discovered. Some of these were practical and were adopted, such as fire- proof suits and other products (fig. 3). Some, on the other hand, were not well received by the public, like the refillable asbestos cigarette paper introduced in England during the 1880's [38]. If Figure 3. Illustration of some early asbestos products, Jones [38]. 5

Actually, industry was rather slow in adopting asbestos. Even after the discovery of the extensive and high-quality Canadian chrysotile deposits, asbestos-industrialists spent more time promoting their product than manufacturing it,7 at least for a few decades. After the turn of the century they began to succeed and asbestos soon became one of the most widely used industrial minerals.- Asbestos in mineratoriv Although there were several references to asbestos in the ancient literature, the first scientific-type descriptions were offered relatively late by Dioscorides [20] and Plinius [55]. Dioscorides called it auiavrco amiantos (meaning immaculate, unpolluted) and Plinius added a comment that the Greeks used to call it aosaatoo, asbestos (meaning incombustible, unquenchable, inextinguishable). Plinius also used the Latin name of linum vivum for the same mineral as he believed it to be a plant from India; a plant which grew in a part of the earth burned completely by the sun, thus became accustomed to that environment and learned to survive in the flame of fire. During the scientifically dormant Middle Ages the nomenclature of Dioscorides and Plinius was neither challenged nor modified. Of the two names of asbestos, amiant appeared to be the more popular. Almost two centuries ahead of the era of the scientific revival, Agricola [1] offered in 1546 the first criteria for mineral identification. According to Werner [66], Agricola recognized several basic categories of mineral properties such as color, transparency (translucida), resplendence (fulgor), luster (mitor), weight (gravitas), hardness (durities), flexibility (flexibilitas), cleavage (fissio), etc., and used descriptive terms as: globular (figura globi), cyclindrical (figura cyclindrica), conical (figura metae), hair-like (figura capillorum), star-like (figura stellarum), etc. It is easy to recognize in Agricola's expressions the prototypes of some modern terms. Although he did not expand our knowledge of asbestos, he did introduce the descriptive term capillary (haarf6rmig, hair- like) which was adopted later for the description of the shape of asbestos fibers. The next stage of development in mineralogy was during the 18th century when scientists began the development of a mineralogical system divided into orders, classes and species on the basis of common and distinct external properties. These followed the natural history concepts and criteria used in botany and zoology. The first and still relatively crude classification was offered by Walerius [65] and by Cronstedt [15] and the first significant improvement of Agricola's list of external characters of minerals, and its application in mineral classification, was offered by Linneaus [47]. The term fibrous (fibrosum) appeared in his list of descriptive terms for minerals composed of parallel fibers. This period was closed by Werner who published the first comprehensive and consistent system of mineralogtr in 1774 [66]. He exerted unparalleled influence on the future development of mineralogy.8 His influence extended from the wide-spread acceptance of his svstem of mineralogy to the establishment of mining schoois in many countries and to the practice of naming new minerals after personal names. In his classification system, capillary is to be used for the description of asbestos fibers and fibrous is used to describe the breakage of bundles of fibers into small fibers.e He constructed a complete system of minerals of about 300 species. Although never published, it was spread by his students and fellow m neralogists [34,26], and was.adopted all over the 7Jones' book [38] may have been inspired by similar interests. He writes [38, p. VI] that "he hopes by this means (writing the book) to ... tend to develop the uses of" asbestos. °Werner used the name orvctoanosy for determinative mineralogy, after the Greek opvtoo (fossil) and yvaota (to know). sNote that there is very little difference between saying that (1) fibrous crystals grow in bundles of fibers (as we would say it today) and (2) a bundle of fibers breaks down to fibrous crystals. However, the use of fibrous as a description of breakage was soon changed to a description of texture or habit by &lum (5, p. 30], Thomson [61, p. 2567, Phillips [54, p. XXXVI and LXXII], etc. 6

civilized world, even before his death in 1817. In his system he recognized one asbestos species, with four subspecies, and two other [26] subspecies, asbestartioer or asbestarticher, one of actinolite and one of tremolite.so Werner recognized a number of other fibrous, but not "asbestartiger" mineral varieties. He called those strahliger or fasriger. Jameson [36,37] translated Werner's terminology into English as asbestous, rism tic, and fibrous,x' respectively for asbestartiger, strahliger, and fasriger. The comparison of the appropriate portion of Werner's and Jameson's classification are given in Table 1. Table 1. Comparison of Warner's and Jameson's classification of asbestos and some fibrous minerals. Werner, after Fretesleben [26] Jameson [36] ERSTE KLASSE: ERDLICHE FOSSILIEN 3. Kiesel Geschlecht Spischaft des Pistazits 52. Anthophyllite a. strahlicher Sipschaft des Zeoliths 75. Prehnit a. fasricher 77. Zeolith b. Faser - Zeolith 5. Talk Gaschlecht Sipchaft des Talks CLASS II. ORDER VI. SPAR Genus I. Schiiier Spar S. Prismatic Schiller Spar or Anthophyllite Genus IV. Prehnite 1. Axotomous Prehnite 2d Subsp, Fibrous Genus IV. Zeolite 7. Prismatic Zeolite lst Subsp. Fibrous Genus VIII. Augite 137, Asbest 2. Hemiprismatic Augite a. b. Bergkork Amianth 4th Subsp. Actynolite lst Kind Asbestous c. d. gemeiner Asbest Bergholz 2d 3d -- Common -- Glassy Sipschaft des Strahlsteins 5th Subsp. Tremotite 138. Strahlstein 1st Kind Asbestous a. asbestarticher 2d -- Common b. gemeiner 3d -- Glassy c. d. giasicher kbrnicher 6th Subsp. Asbestus lst Kind Rock-Cord 141. Tremolit 2d -- Flexible Asbestus a. asbestarticher 3d -- Common Asbestus b. gemeiner 4th -- Rock-Wood c. glesicher 'oThe actual names of classification units vary from author to author. In order to avoid the lengthy comparison of the expressions used by different authors only "species", "subspecies", or "varieties" are used in the text (instead of "subspecies" and "kinds" of Jameson, for example). "Phillips and Allen [54, p. LXXII] used asbestiform as well as a special term fasciculated for minerals composed of fibers or acicular crystals occurring in bundles. 7 2063104809

i Jameson's asbestous was soon changed to asbestiform in English mineralogy textbooks: Thomson in 1836 61, L, p. 22;, Phillips and Allan in 1838 [54, p. 58] and QanaSZ in 1857 [17, p. 153]. Ha"uy [36] also adopt2d Werner's basic system and terminology, and translated most of his German terms into French, although he practiced more flexibility than Jameson did as he introduced a more chemical classification scheme. However, he makes no apparent distinction between asbestos and other fibrous varieties and uses the term fibreux for all. He trans- lated Werner's asbestartiger Strahlstein and Tremolit as Actinot~breux and Grammatite fibreuse,13 fasriger Prehnite as Prehnite fibreuse, and straliger Antophyllit as anthophyl- lite aciculaire. Although he does not distinguish between asbestos and other fibrous crystals, he seem to restrict the use of fascicle, and to a lesser degree fibre, to asbestos fibers. The term filamenteux was introduced into the French mineralogical 7iterature by Brard [7], asbestoid by Beudant [4, p. 369] and asbestiforme by Cloizeaux [13, I, p. 80] as equivelent expressions for the German asbestartig and the English asbestiform. It should be noted that all these early mineralogists, including Werner and his followers, used the term fibrous in a general sense and considered asbestiform (asbestous, asbestartig, feinfaserig, asbestoid) as a special class of fibrosity. Although none of them have defined the uniqueness of asbestiform fibrosity, the reason for that distinction was implied in their recognition of the unique properties and appearance of asbestos, including the unusual strength of asbestos fibers. Hoffmann (and Breithaupt) [33, IIb, p. 307], for example, pointed out that the asbestiform variety of tremolite is less brittle, that is, stronger than the common prismatic or acicular variety. i r t Figure 4. Handcolored illustrations of Schilletnder Asbest (Amianth) and gemeiner (comewn) Tremolit in Schmidt's Mineralienbuch [60]. i2At the bottom of this page Dana gives some exercise questions like: What is the crystal- lization of hornblende? Mention the characters of the varieties of actinolite - (i.e., glassy, radiated, asbestiform, massive). L3occasionally, however, he used the German word "asbestartiger" in the French text without translation. a

Werner's historical system of mineralogy was used without fundamental modifications for over a century, especially in popularized mineralogy books like that of Schmidt's [60]. Werner's strong influence on mineralogy resisted, for some times, the acceptance of the proposals of a new breed of mineralogists who advocated to change the system of mineralogy from the "natural history" type to a more chemical one. Mineralogists like Thomson [61], Beudant [4], Berzelius [57], Rammelsberg [56], and others believed that the chemical properties of minerals are much more important than their external and physical properties. Thomson was a strong opponent of the classification of minerals on the principles of natural history. He was especially critical of Mohs [49] who carried the natural history approach to such an extreme that it almost became free of chemistry. Thomson came out to say [61, p. 8]: "It appears to me, that mineralogy is so closely connected with chemistry, and so dependent on it for its specific distinctions that it would be highly injurous to it, and therefore, very unwise to attempt to deprive it of so important an ally." In line with the emphasis on chemistry came a new classification and the redefinition of mineral species. All those former species which had no distinct chemical composition were discredited. This included the degradation of Werner's one asbestos species to the rank of variety. Of course, asbestiform actinolite and tremolite were already considered variations (or subspecies) by Werner himself. Asbestos and its subspecies became classified, on the basis of relatively poor and inconsistent chemical analysis, as variations of amphiboles, epidote, pyroxenes, talc, and tourmaline by Beudant [4, p. 837], for example. Rammelsberg expressed this philosophy of the reclassification of the former asbestos species" [56, Part II, p. 313] as: "Mineral substances described by the name of asbestos (or amiant) do not appear to constitute an independent species. As their chemical composi- tions indicate, and it may be more appropriate as noted by Breithaupt, that the name asbestos represents a condition which can be obtained by several, thoroughly different kinds of minerals." (emphasis by author) Berzelius, the Swedish chemist-mineralogist (also the major promoter of the "blowpipe analysis" which became one of the major mineralogical techniques for more than acentury), was one of the most ardent pioneer advocates of this "scientific" system of mineralogy. In his 1846 publication [54, p. 213-214] Berzelius states that mineral s ec~ies as previously defined don't exist. He proposed that instead of species, m nerals should be identified and classified on the basis of: "ingredients and different chemical proportions...as well as their definite bonding relationships." (Yerbindungsverhtiltnisse = 2= crystal structure.) The transfer of mineralogy from Natural History to Chemistry did not take place as proposed by Berzelius and his compeers. Instead, mineralogy developed gradually in that direction and assumed a unique position among the sciences, a status of transition between natural history and physical sciences. The concept of species was not fully abandoned either. In fact, with the meaning redefined in a chemical context, "mineral species" is still used today by some mineralogists, like Berry and Mason [3, p. 272-274]. The classification of minerals was also changed during the second half of the 19th century from categories of "common external properties" to groups of chemical units. Mineral species or individual minerals were defined by their chemical composition and crystal structure. Of course, crystal structures were not known at that time. Consequently, they had to be substituted for by the observable consequences of the crystal structure: the crystallography and physical- chemical properties of minerals. That is, if two minerals had the same composition but had different crystallography and physical properties they were considered to be two distinct minerals. That criterion was readily applicable to minerals which occurred in good crystal forms. However, the same could not be used for asbestos where there was not crystallographic Y4In the same book Rammelsberg recognized Krokydolite (crocidolite), named by Hausmann in 1831, as an independent species. That may, at first, look like a contradiction in his philosophy. However, it is not, as crocidolite's parent mineral riebeckite was only discovered many years later, in 1888, by Sauer. 9 2063104811

data and the only non-chemical information available was the difference in the tensile strength and flexibility of the asbestiform versus the compositionally equivalent non- asbestiform mineral. That difference was considered by many mineralogists to be sufficiently distinct to warrant the recognition of some asbestiform varieties as independent minerals. Several dozen asbestos mitaerals were proposed and accepted during this stage of evolution.15 The chemical compositions of most of these asbestos minerals were known and their chemical identity with other minerals were recognized. The compositional equivalence of chrysotile and serpentine was realized since Kenngott's publication [40] in 1853. That was sufficient for some mineralogists to declare chrysotile as a variety of serpentine. Others, however, still considered the differences in physical properties sufficiently significant to recognize chrysotile (under various names, like: metaxite, schweizerite, etc.) and serpentine as two distinct minerals. The other two major asbestos minerals, byssolite and crocidolite, were known to match amphibole compositions, byssolite since Scheerer's 1851 analysis [59] and crocidolite since Delasse's 1847 analysis [i9]. Crocidolite was first believed to be an asbestiform variety of arfvedsonite [50, p. 461] in spite of minor chemical differences. However, as soon as riebeckite was discovered by Sauer in 1888, crocidolite was reclassified by Naumann (and Zirkel) [51, p. 707], as its asbestiform (Asbestform in German) variety. As a consequence of the undecisive significance of differences in physical properties versus compositional identities, the classification of asbestos minerals as independent minerals or as varieties was a function of the individual interpretation of mineralogists. For example, Hintze [317, Groth [297, and Naumann (and Zirkel) [51] recognized chrysotile as a variety of serpentine and crocidolite as a variety of riebeckite; E. S. Dana [16] classified both as independent species; Klockmann [41] and Rogers [58] recognized chrysotile as an independent mineral and crocidolite as a variety of riebeckite. The asbestos nomenclature was further complicated during the last decades of the 19th and first decades of the 20th century when asbestos became a major industrial material. The industrially useful properties of asbestos obtained from certain deposits differed somewhat from that of others, and on the basis of that some asbestos were given distinct mineral names, usually reflecting the name of a mining company or district (for example, bostonite: Boston Asbestos Packing Co.; amosite: Asbestos Mines of South Africa; montasite: Montana mine, South Africa; prieskaite: Westerburg mine, Prieska, South Africa . he use of these distinct mineral names, of course, provided some promotional advantages. The majority of these commercial mineral names never got into mineralogy text books, and those few which did were subsequently eliminated or discredited. Amosite, for example, was formally discredited in 1946 [2]. The discovery of x-ray diffraction produced a tool available for crystal structure determination. As the basic crystal structures of the former asbestos minerals were proven to be identical with that of compositionally equivalent major minerals they were all degraded to the rank of varieties, without further arguments. For example, the final decision on crocidolite's mineralogical identity with riebeckite was provided by Whittaker in 1949 [67] and by Drysdall and Newton in 1960 [22]. The asbestos varieties of minerals were consequently identified by the prefix of fibrous or asbestos-like [24, p. 578] or asbestiform (see Table 2 for details). Fibrous16 was used as a more general term to include both asbestiform and non- asbestiform fibrous minerals. However, asbestiform was always restricted to asbestos varieties, as that was done consistently since Werner s time, 200 years ago. tsThese asbestos mineral names included: Adigenite, agalite, antholite, baltimorite, beaconite, cyclopeite, dermatite, fibrolite, griquanlandite, hydrophite, ishkyldite, karachaite, kolskite, kymantine, metaxite, nemalite, picrolite, retinalite, rezhikite, rhoduzite, schweizerite, vorhausite, williamsite, zermattite, zillerite, xylotite, etc. 1eFord [24, p. 204] gave a more liberal definition of fibrous than usual. He states that "fibres may or may not be separable" in a fibrous mineral. 10

e Z3 Table 2. Descriptive term~ used by mineralogists to distinguish between asbestos and other types of fibrous textures. (Frequently in conjunction with fibrous.) Page number of an example is given. Werner (Friesleben) asbestartich Naumann [50, p. 324] asbestartig [66, p. 107 Naumann (Zirkel) Asbestform HaDy [30] no distinction [51, p. 707] Hoffmann (Breithaupt) asbestartig Nicol [52, p. 152] asbestiform [33, 2b, p. 306] Tschermak [62, p. 444] ? feinfaserig Jameson [36, II, p. 22] asbestous Groth [29, p. 151] asbestartig Phillips (Allan) asbestiform [54, p. 58] E. S. Dana [16, p. 384 asbestiform Thomson [61, I, p. 481] asbestiform Hintze [31, II, p. 1195] ? feinfaserig Mohs (Haidinger) asbestous Klockmann [41, p. 567] ? feinfaserig [49, II, 27] Doelter [21, II, p. 589] asbestartia Beudant [4, p. 387] asbestoide Rogers [58] no distinction Brard [7, p. 206] filamenteux Ford [24, p. 578] asbestos-like Bium [5, p. 242] ? feinfaserig Hurlbut [35, p. 446] asbestiform Rammelsberg [56, p. 358] asbestartig Kraus, Hunt, Ramsdell asbestiform Schmidt [60, p. 358] asbestartig [43, P. 392] Bristow [9, p. 85] asbestiform Berry, Mason asbestiform [3, P. 527] Cloizeaux [13, p. 81] asbestiforme Deer, Howie, Zussman asbestiform J. D. Dana [17, p. 153] asbestiform [18, II, P. 2431 a French: fibreux; German: faserig. The term fiber, in reference to asbestiform fibers, was equivalent to the concept of organic fibers because the early natural historians believed that asbestos was actually a vegetable. Mineralogists from the 18th century on did not specifically state that the term fiber is used because of its resemblance with organic fiber. However, that reasoning is apparent in their description of asbestos fibers as hair-like or capillary or thread-like, and in the types of names they have given to asbestos minerals, such as mineral-wood, rock- cotton, mountain cork, rock-wood. Jones [38] provided extensive details in the description of the similarity between asbestos and organic fibers (fig. 5) and concluded [38, p. 221] that: "The nature of the asbestos fibre is thus so far identical in structures with the organic fibres." - 11 N 0 a w 0 A 00 M+ W

C;w Fg. 1. Bibrv of 9hoo '* p WaaL Magti@°d Fig. 2. Filnmenh B00 of Naw Cattan. di.mchn. No. 1.-TLOtfmd On. Fig. 5. 8pun Ghw. Nn. 7. 13etfo~d O». Figure 5. Jones' [38] comparison of asbestos and organic fibers. Although the use of the term fiber has not been restricted to asbestos and included a number of other minerals they all had some characteristics reminiscent of organic fibers. In any case, the term fiber has never been used as a description of the elongated shape of crystals. For that acicular is the proper mineralogical expression. The term asbestos was first a species name, as noted earlier it was introduced by Werner and his school. Later it became a collective term, like c1Tys or gems, in reference to asbestiform varieties of a number of otherwise unrelated minerals. Parallel with the mineralogical terminology asbestos also became an industrial term for a category of mineral products containing asbestiform varieties of silicates. However, some commercial asbestos may be mixed with non-asbestiform acicular crystals or cleavage fragments. The quality of asbestos is related to: (a) the extent of the development of the preferred asbestos character (high tensile strength, flexibility, length of fibers) of the asbestiform fibers, and (b) the percentage of the less desirable non-asbestiform, acicular crystals or cleavage fragments present in the product. That is, the mineralogical and industrial definitions of asbestos are not fully coincident. The unusual properties of the asbestiform fibers were always recognized by the early users of asbestos as well as by mineralogists. These properties included high tensile strength [for example, 32,33,38,64], increased flexibility (noticed by all mineralogists), unexpected optical properties [for example, 53,69] and differences in surface properties, like surface charges [for example, 28,42,45,72]. VO Fig. 3. Fig. 4. Fibro of p,adint'Chro.d of HsvSilk Gmden Spid.. . 12