219
The Catndian Mineralo gist Vol.35, w. 219-246(I9W)
NOMENCLATUREOF AMPHIBOLES: REPORT OF THE SUBCOMMITTEE ON AMPHIBOLESOF THE INTERNATIONAL MINERALOGICAL ASSOCIATION. COMMISSIONON NEWMINERALS AND MINERALNAMES
BERNARD E. LEAKE1 (Chairman) Departrnewof Geolngyand Applied Ceoln, Universityof Glnsgow,Glasgow G12 8QO U.K. ALAN R. WOOLLEY (Secretary) Depamnentof Mineralogy,Nafiral HistoryMweun CromwellRoa{ InndonSW 5BD,U.K CHARLES E.S. ARPS* (Ihe Nethedands;retired December1994) WILLIAM D. BIRCH* (Ausftalia; from January1995) M. CHARLES GILBERT (U.S.A.; resigned1994) JOEL D. GRICE (Canada;*from January1995) MhrcralSciences Division" Canadian Maseam of Nanre,P.O. Box 3443, Statian D, Oftang OntarioKIP 6P4,Canada FRANKC. HAWTHORNE Departnentof EanhSciares, University of ManitobaWinnipeg, Manitoba R3T 2N2, Cmada AKIRAKATO Departnzntof Geology,Natural Science Mu*em\ 2-23-l Hyakanin-cho,Shinjuka Tolqo 160, Japan IIANANJ. KISCH Departrnewof Geologyand Mineralogy, Ben Gurion Univercity of theNegev, P.O. Box 653, M105 Beer Shzva" Israel WADIMIRG. KRTVOYICTMV Facultyof Geolngy,St. Petersburg University, University Emb. 7/9, 199034 St. Petersburg, Rwsia KEES LINTIIOUT Department of Ore Geology, Petrology and Mineralogy, Instiate of Earth Sciences, Free University, De Boelelaan 1085, 1081 HV Amsterdam" Thz Netherlanls JO LAIRD Departruntof EarthSciences, College of Engirceringand Physical Sciences, University of NewHanpshire, Durhatn,New Hampshire 03824, U.SA JOSEPHA. MANDARINO* (Canada;retired December1994) WALTERV.MARESCH Instintftr Mineralogie,Ruhr-Universitdt Bochum" D44780 Boclwtn, Germary ERNESTH. NICKEL* (Australia) MCHOLAS M.S. ROCK (Ausftalia; died February1992) JOHNC. SCHUMACTIER Institutfilr Mineralogie-Petrologie-GeochsniedzrAlben-Iad.wigs Univenitilt nr Freiburg,Albertstrasse 2jb, D-79I M Freiburg,Germany DAVID C. SMITI{ @rance;resigned 1994) NICKC.N. STEPIIENSON Departnentof Geologyand Geophysics, Unfuersity of NewEnglan4 Anniilak, NewSoathWales 2351, Aastralia LUCIANO UNGARETTI (Italr resignedApril 1993) ERIC J.W. WHITTAKER 60Exeter Roa4 Kidlingtoa Oxford U$ 2DZ U.K GUO YOITZHI CentralLaboratory, Bureau of Geologyand. Mineral Resources of Hurwwt.Province, Da:hiba" Kwtming, P.R Chha
*Indicates anonvoting official of the CNMMN. I E-mail address: [email protected] 220 TI{E CANADIAN MINERALOGIST
AssrRAcr
The Intemational Mineralogical Association'sapproved amphibole nomenclature has beenrevised in order to simplify it, makeit more consistentwith divisions generallyat 50%, defineprefixes and modifiers more precisely,and include new spcies of amphibolediscovered and namedsince 1978,when the previous schemewas approved.The samereference axes form the basis of the new scheme,and most n:rmesare little changed but compoundspecies names like tremolitic homblende(now magpesiohomblende)are abolished,as are crossite(now glaucophaneor ferroglaucophaneor magnesioriebeckiteor rieb€ckite), tirodite (now manganocummingtonite)and dannemorite(now manganogrunerite).T\e50Vo rule has beenbroken only to retain tremolite andactinolite asin tle 1978scheme; the sodic--calcicamphibole range has therefore been expanded. A1kali amphiboles are now sodic amphiboles.The useofhyphens is defined.New amphibolenames approved since 1978include nybdite, leakeite, kornite, ungarettiite,sadanagaite and cannilloite. All abandonednarnes are listed. The formulae and sourceoffhe amphibole end-membernames are listed, andprocedures outlined to calculateFe3+ and Fe2+where not determinedby analysis.
Keywords: amphibolenomenclature, crossite, dannemorite, tirodite.
SoNnuens
k schdmade nomenclafineapprouv6 de l'Associa.tionmin6ralogique intemationale est ici r6vis6 afin de le simplifier, de le rendreplus confonnei la rdgledes suMivisions i 507o,d'en d6finir plus pr€cisdmentles pr6fixeset les qualificatifs,et d'y inclure les nouvelles especesd6couvertes et approuvdesdepuis 1978, date de publication du rapport antdrieur.I.es m€mesaxes de r6f6rencesont retenusdans le nouveausch6m4 et la plupart des noms sont peu chang6s.En revanche,les noms d'espdce compos6s,par exemplehornblende tr6molitique (d6sormais magndsiohomblende), soff abolis,de m6meque crossite(ddsormais glaucophane,ferroglaucophane, m:gn6sioriebeckite ou riebeckite),tirodite (d6sormaismanganocummingtonite) et dalnemorite (ddsormaismanganogrunerite),I-a,rE$e de 507on'est fansgress6eque pour le maintiendes es$ces tr6molite et actinolite,dont la d6finition reste inchang6edepuis le rapport de 1978, de telle sorte que le domaine occupdpar les amphibolessodiques- calciquess'en trouve agrandi.Irs amphibolesalcalines sont maintenantappel&s amphibolessodiques. L'utilisation destraits d'union est pr6cis6e.I,es espBcesd'amphibole suivantes ont 6td appouvdesdepuis 1978: nybdite, leakeite, komite, nngarettiite, sadanagalteet cannilloite. Tous les noms mis e l'6cart sont indiqu6s.Nous donnonsla forrnule chimique et I'origine des noms despOles des amphiboles, ainsi que les procddurespour calculerla proportionde Fd+ et de Fea da:rsles casof elle n'a pas 6tf d6termin6edirectement. (Iraduit par la R6daction)
Mots-cl6s: nomenclature,amphiboles, crossite, dannemorite, tirodite.
INTRoDUCTON (5) representationwas soughtacross the various fields concemedwith amphibolenomenclature, from crystal- This report was producedin responseto a motion at chemists, metamorphic and igneous petrologists to the IMA 1986 meetingin Stanford,Califomi4 asking computer experts and ordinary broad-basedpetrolo- the CNMMN to producea more simplified nomencla- gists. There were 18 voting memberswhen the major ture of amphibolesthan that currently approved,which framework of the revisedscheme was approyed. dates from 1978. The 1978 nomenclature(IMA 78) The committeecirculated over 1000pages over nine took over 13 yearsto formulate;a quickerresponse was years,and consideredin detail all proposalsmade to it. atlemptedthis time. Views were expressedthat becausethe amphibole To ensurea fresh look at the nomenclaturescheme, systemis so complicated adequaterepresentation can- the Chairman of the Amphibole Subcommifree,Prof. not be madewith two- andthree-dimensional diagftuns, B.E. Leake, with the agreementof the CNMMN offi- whereas four variables can represent the system cials, completelyreconstituted the commifteeso that (1) adequately.However, the committee,by a very large representationwas more international; (2) more than majority, wantedto retain conventionalnomenclature- 807oof the y6 ;ng membersof the committeewere not diagramsbecause they are easierfor most scientiststo members of the committee that produced the 1978 use. The commifiee considereda range of different report; in additioq none of tle CNMMN officials was schemesof nomenclature,but none wasjudged overall on the 1978 committee; (3) three members were to be sufficiently better to justi$ abandoningthe main retainedfrom the 1978 commiueeto ensurethat there basis of IMA 78, which has beenwidely acceptedand w.rssome continuity andcollective memory of ttremain is capable of simplification to provide an improved problemsthat had been dealt with previously: (4) rep- scheme.It must be rememberedthat over 957oof all resentation included the principal proposer to the amphiboleanalyses are currently obtainedby elecfron CNMMN of an improved schemeof nomenclature; mictoprobe,withno stuchrel informatio&no knowledge 221 of the oxidation states of Fe, Ti and Mn, the H2O The classificationis basedon the chemicalcontents content,or how the site populationsare derived.What of the standard amphibole formula AB2vC5NTgOz2 follows is a schemeof nomcnclatureonot one to deter- (OH)2.It is to be noted,however, that possessionof this mine at which position the ions really are located. formula doesnot define an amphibole.An amphibole The proposedscheme involves reducingthe number must have a structurebased on a double silicate chain: of subdivisions,especially in the calcic amphiboles, a biopyribole consistingof equalnumbers of pyroxene making the divisions generally follow the 50Vo rsle chains and tiple chains would have this fornula, but (whereasIMA 78 usesdivisions at 904o,70Vo,67Vo, would not be an amphibole. 50Vo,33Vo, 30Vo and L07o),atd making the use of The components of the formula conventionally adjectivalmodifiers (additionalto prefixesthat arepart describedas A, B, C, T and "Olf' correspondto the of the basicnames) optional. The new schemehas over following crystallographicsites: 20 fewer namesthan IMA 78, and involves the abot- A one site per formula unit; tion of only a few commonly used na:nes, such as B two M4 sitesper formula unit; crossite.End-member fprmulae defined and approved C a composite of five sites made up of 2 ML, in IMA 78 are generallyretained, althougb the ranges 2 M2 and I M3 sitesper formula unit; to which they apply have commonly been changed. T eight sites,in two setsof four, which neednot lnformation on the etymology,the type locality, andthe be distinguishedin this document; unit-c€ll parametersof thirty end-membersis provided "OIf' two sitesper formula unit. in Appendix 1. The ions consideredrcrmal$ to occupy thesesites The principal reference-axesof IMA 78, narnelySi, are in the following categories: Nas and (Na + K)a (seebelow), are retained but the n (empty site) and K atA only primary divisions betweenthe calcic, sodic-calcic and Na atA or B alkali (renamedsodic) amphiboleshave been adjusted Ca at B only to divisions at Nas < 0.50 and Nar > 1.50, insteadof Z-type ions: Mg, Fd*, Mn2*, Li and rmer ions of similar size,such as Zn, Ni, Co at C or B Nas< 0.67 andNas 2 1.34.(Here, and elsewherein this M-$pe ions:Al atc otT report, concentrationsare expressedin atoms per Fe3*and, more rarely, Mn3+,Cr3+ at C only formula unit of the standardformula of an amphibole High-valencyions: Tia at C or T given below.) Previously, the amphibole oobox"was 7* at Conly divided into three equal volumes with respectto Nap. Si at Zonly The new schemeenlarges the sodic--calcicamphiboles Anions:OH, Cl, O at'Olf'. at the expense of the calcic and sodic amphiboles R (Fig. 1) in orderto makethe divisions at 507opositions. M-tWe ions normally occupy l[2 ites and so are normally limited to two of the five C sites.Exceptions As with the 1978scheme, the problem of what to do rnay occur to the above oonormal"behavior, but are with analysesin which onlythe total iron is known (and ignoredfor the presentpurposes of nomenclature. not its division into FeO and Fe2O3)has been left to Throughoutthis report, superscriptarabic numerals individual judgement althougha recommendedproce- refer to ionic charge(oxidation state),e.g., Fd*, super- dure is given. This meansthat again an analysismay script roman numerals,to coordinationnumber, e.9., yield different names dependingupon the procedure uAl, and subscript numeralsoto numbers of atoms, used to estimateFe3* and F**. It clearly would be e.B.,Ca1 advantageous, purposesofnaming an amphibole,if for To take accountof these facts, it is recommended the recommendedprocedure were followed, even if that the standardamphibole formula be calculatedas other procedureswere usedfor other purposes. follows, though it must be clearly appreciatedthat this Generalworks dealing with the amphibolesinclude is an arithmeticconvention tha.t assigns ions to conven- Ds et aL (1963,1997),Emst (1968), Chukhrov (1981), ient and reasonablesite-occupancies. These ca:rnot be Veblen (1981),Veblen & Ribbe (1982), Hawthome confirmedwithout direct structuralevidence. (1983)and Anthony et al. (1995),tuomwhich adequate (1) If H2Oand halogen conte,nts are well established,the generalbackground summaries can be obtained. formulashould b€ calculatedto 24(O,OHF,CD. (2) If the H2O plus halogen cont€nt is uncertain,the GENERAL CLASSFICATTON oF T}IE AMPHIBOLES formula shouldbe calculatedto the basisof 23(O) with 2(OH,F,CI) assumedunless this leads to an As with the IMA 78 scheme,the proposednomen- impossibility of satis$ing any of the following clature is based on chemistry and crystal symmetry; criteria in which casean appropriatechange in the where it is necessaryto distinguishdifferent polytypes assumednumber of (OH + F + Cl) shouldbe made. or polymorphs,this may be done by adding the space (3) Sum Z to 8.00 using Si, then Al, then Ti. For the group symbol as suffix. Anthophyllite having the sym- sake of simplicity of nomenclature,Fe+ is not metry Pnmn (as distinct from the more usual Pnma allocatedto 7. The nonnal maximum substitution symmetry)may be prefixed proto. for Si is 2, but this can be exceeded. 222
o !, Na" a d. o I = oro o =o o o = ! o q3 o E !t tu d E: *A A o o 60t p o do. o gro .T. o tr tr z n z s=8o o p !\) vo C) r Ol cr a€@ () Fc) gd' 3 G "sF F gd N to F !2tr b o a z a -o @o -{n _N pe po 66 o @N rgt sl o 5N- ol T g 9d 6- al * d-(/, p- Y ;II )6 o 6 Pg= x o o <9-o N X3 R o qg T 0 oo p- ooN o tr tr:. -o oo qa ao I il^9 H @= aF 'i XA gE6< + F 3> "5 qN60 z zl! qo D p- 'nF oo u o i€q Ed; ,tr FNo 3 N 6 T I p- N-o N z z!' r a\H o N €B r @ 9B- a *!t o tr L* o @E o o \ gLB 10tr ti ^f pp9 E g a (t, 888 p=Ra 6- z z z!! .o FT o o 6C) !a fo z o o f- T ON .o 3 F- !t F'o=P:.9 P .5- i i $N:' =N ct o- E(/) c) I 888 888 I a q o- as=Bo F N €Fs"B sz -Pz N dso E - -$ o b T 6 N T o $- "5 T 223
(4) SumCto 5.00using excess Al andTi from (3),and (4) Where Na3 is ) 1.50, then the amphibole is a tlen successivelyZx, Cf+, F93*,Mn3*o Mg, Fe2t, member of.the sodic group. previouslyreferred to Mn2*, any other Z2{Upe ions, and then Li, as alkali amFhiboles. The new name is more (5) Sum B to 2.00 using excessMg, F*+, Mnz* and Li precise,as Na is the critical element,not any other from (4), then Ca, then Na alkali elementsuch as K or Li. (6) ExcessNa from (5) is assignedto A, then all K. Within each of these groups, a composition can Total A shouldbe between0 and 1.00. then be named by reference to the appropriate two- dimensionaldiagram (Figs. 2-5). Theseare subdivided The most coulmon uncertaintyresuhs from lack of with respectto Si and Md(Mg + Fe2*)or Mg/(Mg + analysesfor H2O,Fe3* and FeP*. The procedureadopted NW*),withprefixes to indicatemajor substitutions,and to divide the Fe into Fe3* and FeP*can influence the less important substitu- resulting name, especially if a composition is near oprtonal nndifiers to specify tions. Mg(Mg + Fd.) = 0.50or Fd+/(Ire3++ vIAl) = 0.50,i.e., groups, the samebulk compositionmay give rise to two ormore Within the the amphibolesare divided into namesdepending upon the allocation of the Fe. The individually named species distinguished from one committee was almost unanimousin not wanting to anotheron the basisofthe heterovalentsubstitutions: Si = rvAl, tr = (N4K)a, = = = specify one compulsoryprocedure for allocating Fel Ca3 54", Li L2*, Mc Lbc, (li,Zx) = = (OH"F,CI). and Fd*, but in recommenling that a commonproce- Ic, O Thesesubstitutions nec- pairs dure be wed purposes of narning the amphibole. essarilyoccur in or multipletsto maintainneufral- for shown in Rock & Leake (1984) showed that, on the basis of ity. The speciesdefined ea this basis are processingresults of over 500 amphiboleanalyseso the Figure I and along the horizontal axesofFigures 2-5. 'ng IMA-favored procedureof adjus the sum (Si + Al + Different speciesdefined in this way correspondto Cr + Ti + Fe + Mg + Mn) to 13 by varying the Fd* and different dishibutionsof chargeover theAo B, C, Toand 'OIl' quan- Fdt appropriatelygave Fe3* and Fe?* values reasonably sites.Discovery of amphiboleswith new or close to the true determined values in 807o of the titatively extendeddishibutions of charge over these compositionsstudied excluding those of kaersutite,for sites would merit the intoduction of new species the calcic, sodic-calcic and sodic amFhiboles.If this names. sum is adjustedto include Li andZr, i.e., (Si + Al + Cr Within the species,there occur homovalent substitu- = rr'IAl= + Ti + Zr + Li + Fe + Mg + Mn) = 13, and if for the tions, most commonlyMg F**, Fe3+and OH = Mg-Fe-Mn-Li amphibolesthe sum (Si + Al + Cr + Ti F. The end membersof theseranges of substitution +Zr +Li+Fe + Mg + Mn + Ca)= 15is used,then only are distinguishedby the use of prefixes, one or other end memberusually having a fraditional namewithout the Ti > 0.50 amphiboles need special treament a prefix. These substitutions usually correspond to althoughit is recognizedthat Mn-rich amphibolespose independentbinary systemsX - I: the name of the X problemswith the variablevalence state of both the Fe over the range 1.00 > )(X + t) > and Mn and that, as shown by Hawthorne (1983, end memberapplies 0.50, andthe nameof the I endmember, ta 1..00> Yl(X p. 183-185),both in tleory and practiceoany calcula- + Y) > 0.50. For the boundariesof substitutionranges tion of Fe3t and Fe2+values is subjectto considerable in temary systems,see Nickel (1992). uncertainty. A fulI discussionof the problem and a new or exotic recommendedprocedure, both by J.C. Schumacher,are The discovery of amphiboles with never requiresa new species glven as Appendix 2. Someanalyses have given H2O+ homovalentsubstitutions contentsthat lead to more than (OII)z in the formul4 name.They can always be namcd.by we of an appro- priate prefix. but the structurecontains only two sitesfor independent In future, one root or one trivinl name each charge arrange- OH- ions, and the structual role of the extra H ions is ONLY should be approvedfor group, uncertain. mcnt in eachamphibole and.all speciesdefined by homavalentsubstinrtons should be dzsigmted by The amphibolesare classified primarily into four the relevantprefi.x. New speciesdefi.rcdby heterovalent groups dependingon the occupancy of the B sites. sttbstitations[including major replocementof (OH, F, Thesefour principat groups of amphiboleare slightly CD by oxygm, and.major entry of high-charge (>3+) redefinedas compared IMA with 78: cationsfuto 4 B or Q result in new root, or new trivial (1) Where(Ca + Na)sis < 1.00and the sumof Ltype lutm,es, ions (Mg,Fe,Mn,Li)pis 2 1.00,then the amphibole The principal reference-axeschosen for the calcic, is a memberof the magncsiurn- iron - manganese sodic-+alcic and sodic amphibolesare as in IMA 78, - lithium group. namely Nas, (Na + K)a, and Si, as shown in Figure 1, (2) Where (Ca + Na)s is > l.@ and Nar < 0.50, then but the subdivisioninto the sodic-calcic group is now the amphibole is a member of the calcic group. at Na3- 0.50 (insteadof 0.67), andNae - 1.50 (instead Usually, but not in every case,Cas is > 1.50. of 1.34). This increasesthe volume, and thereforethe (3) Where (Ca + Na)3is 2 1.00and Na3 is in the range compositionalrange, assignedto the sodic--calcicam- 0.50 to 1.50,then the amphiboleis a memberof the phiboles at the expense of tle calcic and sodic sodic--calcicgroup. amphibole groups, but is a logical consequenceof 2U applyrng fhe SOVorule for all divisions rather than attacheddirectly to the root name (without a spaceor fiyiding the Na6, (Na + K)a and Si box into equal hyphen) or to a following prefix with a hyphen. A11 volumes,as in IMA 78. The committeeconsidered at thesecharacters distinguish them from modifiers. length various proposalsfor the use of axesother than All modifiers (Table 2) have an 'oian' or oooan" the threechosen, including four components,but even- qrding to indicate moderatesubstitutions, as listed by tually agred by a significant majority, that the IMA Nickel & Mandarino(1987). Modifiers are not accom- 78 axesbe retaine4 despitetheir inability to represent panied by a hyphen, and are invariably followed by a ft* andR$ (i.e. , usuallyL andM-type ions) separately spaceand then the remainder of the name.The excluded in the C group. The imFortance of the difference applicationsfollow from the fact that thesegroups will betweenR2* atrd l?3t in the C group has,however, been usually have substantialcontents of theseelements as recognizedrather more formally than previouslyby tle part of the parametersthat define them. The use of way in which the abundanceof Fd+, Al3+,Cr3+ or Mnl modifiers is optional and strictly qualitative (i.e., they has been defined with prefixes, not moffiers, where can be usedin other sensesthan in Table 2. but use as they occupy 50Voor more of the nonnal maximum of in Table 2 is shongly recommended). 2N*6 as shownin Table l. Following Nickel & Mandarino(1987), prefixes are TID NAI'4nIGoFAt{HmoLEs NTHN SFr"noN an essentialpart of a mineral nane (e.g., ferroglauco- AND }IAND SPTCNMNI phaneand ferro-actinolite),whereas modifiers indicate a compositional variant and may be omitted (e.9., For amphibolesof which the generalnature only is potassian pargasite). Modifiers generally represent known, for instance from optical properties,without subsidiarysubstitutions, whereas prefixes denote major benefit of a chemicalanalysis, it is not generallypossi- substitutions.In order to reducethe numberofhyphens ble to allocate a precise name. The nearestassigned usedoa single prefix is generallyjoined directly to the amphibolename should then be madeinto an adjective, root name without a hyphen (e.9., ferrohomblende), followed by the word amphibole,e.9., anthophyllitic unless two vowels would then adjoin (e.9., ferro- amphibole,tremolitic amphibole,pargasitic amphibolg actinolite) or "an unhyphenatedname is awkward,and glaucophanicamphibole and richteritic amphibole.The a hyphen assistsin decipheringthe nameo'(Nickel & familiar word homblende can still be used where Mandarino L987), e.9., femic-nybtiite.For all amphi- appropriatefor calcic amphibolesin both hand speci- bole namesinvolving multiple prefixes, a hyphenshall *"a aadthin section.because hornblende is neverused be insertedbetween the prefixes, but not betweenthe without a prefix (ferro or magnesio)in the precise last prefix and ttre root name,unless two vowels would classification. such that confusion should not arise be juxtaposed or the name would be difficult to betweencolloquial use and preciseuse. decipher or awkward. This convention gives rise to alumino-ferrohornblende.chloro-ferro-actinolite and flne1e-fsrri-sennilloite.Most (>90Vo)names will lack TABLE 2. MODIFIERS AND TI{EIR SUGGESTED RANGES any hyphens,and less than 57owill havemore than one prefix. M@fog' Appli@bls to In general, excluding juxtaposed vowels, the pre- fixes (Table 1), which haveo, i or ic endings,are either Bqid Br> 0.10 A[ goups Borim B > 0.10 All grcups C€lcie Cs> 0.50 Mg-FFMFLi gmup Chlori@ 0r5 < cl <0.9 All grouF TABLE 1. PREFXESIN ADDITIONTO TTIOSEIN THE NCURES Chonie 0.25
As in IMA 78, asbestiformamphiboles should be Sodic-ferrogedrite NaFeP+dAlSi6Al2O22(OII)2 namedaccording to their preciseminer4l name, as listed -asbestos, in this report, followed by the suffix e.g., Lbnitsfor tfu useof namzsof enl mzm.bers antlophyllite-asbestos,fremolite-asbestos. Where the natureofthe mineral is uncertainor unknown,asbestos Gedrite Me(Mg + Fd+) ) 0.50 aloneor amphibole-asbestosmay be appropriate.If the Fenogedrite Md(Mg + Fd+) < 0.50 approximaienature of the mineral only is known, the Sodicgedrite Me/(Me + Fd*) 2 0.50; Na ) 0.50 aboverecommenda.tions should be followed" but lrith Sodic-ferrogedrite Md(Mg + FeP*)< 0.50; Na 2 0.50 the word amphibolereplaced by asbestos,e.g., antho- phyllitic asbestos,tremolitic asbestos. It shouldbe notedthat gedriteand ferrogedrite,with or without sodic as a prefix, extenddown to at leastSi Mg-Fe-Mn-Li AlrpHBor.Fs 5.50. Discovery of homogeneousNa(Fe$g)dlzSis Al3O22(OII)2wi1ljustiff a new na:ne. The group is defined as possessing(Ca + Na)B < 1.00 and (Mg,Fe"I\{n,Li)a) 1.([ in the standardfor- (3) Holmquistiteseries mula; the detailedclassification is shown in Figure 2. The main changesfrom IMA 78 are the adoption of divisions at Mg1(Mg + FeP*)= 0.50, the reduction of n[jzMgFd*):(Fep*,Al)r]SlEqrr(OII,F,Cl)2. Li > 1.00 adjectives, and tle abolition of tirodite and dan- is critical. nemorite. Endmembers Orthorhombicforms of thc M g-F e-Mn-Li amphiboles Hobnquistite o(Li2Mg3Al)SisO22(OII)2 (l) Anthophyllitesertes Ferroholmquistite E(Li2Fd*3Alrsi8o22 (otl)2
Na,Lt (Mg,Fd*I{n}-}-< Aly(Sis--rz Al,*r)O2(OI1 Lirnitsfor thz we of namesof end members F,Cl)2, where Si > 7.00 (otlerwise the mineral is gedrite) and Li < 1.00 (otlerwise the mineral is Holmquistite Mg(Mg+Fd*)>0.50 holmquistite).Most samplesof antlophyllite have the Ferrohotmquistite Mg(Mg + Fd*) <0.50 Pntno strttctlxe;those with the Pnmn shucturemay be prefixed proto without a hyphen. M onoclinicform.s of the M g-F e-Mn-Li amphiboks Endmembers (1) Cumtningtonite-Gruneriteseries Anthophyllite aMgrSirOzz(OII)z tr(Mg,Fd+Mn"LihSi8O22(OIDz. Ferro-anthophyllite EFe?*zSi8O22(OH Li < 1.00. Most )2 membersof this serieshave spacegrotp C2Jm;those Sodicanthophyllite NaMg7Si7AlO22(OII)2 grovp have symbol Sodic-feno-anthophyllite NaFe2*?Si?AlOu(OH)z with space PJm may orptionally this addedas a suffix at the end of the name. Limi* for the useof natrwsof end members End mcmbers Anthophyllite Md@g+Fd+)20.50 Ferro-anthophyllite MdGvtg + FeP+)< 0.50 Cumningtonit nMg?SisO22(OH)2 SodicanthophylliteMg(Mg + Fd*) 2 0.50; Na ) 0.50 Grunerite trFd+7SisO22(OII)2 Sodic-ferro-anthophyllite Manganocumminglonite oMn2Mg5SfuO22(OII)2 Mg(Mg + F**) < 0.50;Na 2 0.50 Permanganogrunerite trMn4FeP+3SiEO.22W2 Manganogrunerite trMn2Fe2+5SiBO22(OII)2 A) Gedriteseries Limits for the useof natncsof end members Na,I+ (Mg,pd*Idn,-rz At (Sir-,-y*eAl,*r)O22(OH, F,C1)2,where (r + y - z) ) l.fr), so that Si < 7.@, this Cummingtonite Me/(Mg + Fd*) 2 0.50 being the distinction from anthophyllite.Li < l.m. Gnrnerite Md(Mg + FeP*)< 0.50 Manganocummingtonite Md(Mg + FeP+)> 0.50; End mernbers 1.m Mg-Fe-Mn-Liamphiboles DiagramParameters: (Ca + Nas)< 1.00;(Mg, Fe2+, Mn, Li)s> 1.00; LiB< 1.00 Orthorhombic Monoclinic anthophyllite cummingtonite (\tf o I..l. 5 o.s b) = leno- grunerite anthophyllite 8.0 7.0 6.0 8.0 7.0 Si informula Si in formula DiagramParameters: (Ca + Nas)< 1.00;(Mg, Fe2+, Mn, Li)s> 1.00; LiB> 1.00 Orthorhombic I tvtonoclinic 1.0 holmquistite clinoholmquistite qtC o ll. Final namesrequire the relevant prefixeswhich arelisted in 5 o.s Table I andmay optionally includethe modifiersthat are ctt E foundin Table2. clinofenohol mquistite fenoholmquistite ttr : sYmbolsindicate the locationsof end l " memberformulae 0.0 listed in the text. 8.0 7.0 8.0 7.0 Si informula Si in formula Flc. 2. Classificationof the Mg-Fe-IVln-Li amphiboles. NOMENCT/,TIJRE OF AMPHIBOTES ar'7 It shouldbe noted that the namesgiven extenddown Maguesiohasti ngsite NaCa2(Mg4Fd)Si@Al2O n(OH) z to 7.00 Si. If a mineral with lessthan 7.00 Si is discov- g6tingsite NaCa2@d*lFe3)Si@Al2O22(OtI)2 eredo justif then it will a nerv narnebased on the end Tschermakite nCa2(Mgy'1Fe$)Si6A12On(OH)z memberMg5Al2Si6,Al2O22(Of D2. Ferrotschermakite nca2@eP+3AlFe&)si6.Al2o2(oll)2 Aluminotschermakite trCa2(Mg3Al2)Si6A12O22(OII)2 Q) Clinoholmquistites eries Alumino-ferrotschermakite nCaz(FeP+:,AldSi6Al2O22(OII)2 npi2 (Mg,FeP+"I\4n)3@e3+Al)21 si8o22 (oH,F,cl)z. Ferritschermakite trlCa2(Mg3Fe12)SieA12O22(OII)2 Li > 1.00. Ferri-ferrotschermakite uca2(Fd+3Fd"tsi6A2o22(oII)2 Endmembers Magnesiosadanagaite NaCa2[Mg(Fe3*,Al)2]Si5A13O n(OH) z Clinoholmquistite n(Li2Mg3Al2)SisO22(OI{)2 Sadanagaite NaCa2BeP+3@e3*,A1)2lSirAl3O22(oII)2 ClinoferrohoLnquistite n(LizFe2+:.Al)SisO22(OII)2 Magnesiohomblende Ferri-clinoholnquistite tr(Li2Mg3Fe3+rSi8O22(OII)2 Eca2Mg4(A1,Fe*)lsizAlo22(olr)2 Ferri-clinoferroholmquistite Ferrohornblende nCa2[Fd+4(Al,Fe3+)]S1zAIO22(OII)2 :(Li2Fea3Fe12)Si8O22(OID2Kaersutite NaCa2(MgaTi)Si6Al2Oa(OIO Ferrokaersutite NaCazGeP+aTi)Si6Al2Oa(OID Linhs for the useof namesof end mzmbers Cannilloire CaCaz(MgAl)Si5Al3O22(OII)2 Clinoholmquistite Md(Mg+FeF+))0.50 Limits for the useof the narnesof end mcmbers Clinoferroholnquistite Md(Mg+F*+)<0.50 Feni-clinohoLnquistite Fel > l; Theseare summarizedin Figure 3 with respectto Si, Mg(Me+FeP.)t0.50 (Na + K)a, Mg(Mg + Fep+)and Ti. The prefixes ferri Ferri-clinoferroholmquistite Fd* > 1: and alumino are only usedwhere Fe$ > 1.00 and uAl Mg(Me + FeP*)<0.50 > 1.00 (fable 1). For kaersutiteand ferrokaersutite,Ti 2 0.50; any lower Ti contentmay optionally be indi- catedas in Table 2. Qannilloiterequires Ca1 2 0.50. CALcrcAtrlprmolEs Soorc{arrrc Alprmor-Es The group is defined 4s 6snsslinis amphibolesin which (Ca + Na)p 2 1.00,and Nas is between0.50 and This group is defined to include monoclinic amphi- L.50; usually, Ca; 2 1.50.The detailedclassification is bolesin which (Ca+Na)s2 1.00and 0.50 < Na; < 1.50. shown in Figure 3. The numberof subdivisionsused in The detailedclassification is shownin Figure 4. There IMA 78 hasbeen more than halved; silicic edeniteand are no significant changesfrom IMA 78 exceptfor the compoundnames like tschermakitichornblende have 507oexpansion ofthe volume occupiedby the group in been abolished, sadanagaite(Shimazaki et aI. l9B4) Figure l. Becauseof the concentrationof compositions and cannilloite (Hawthorne et al. 1996b) have been relatively near the end members,the increasein the adde{ and the boundariesof the group have been number of compositionsin this group comparedwith revised. Hornblendeis retainedas a generalor collo- the number classifiedin IMA 78 is quite small (much quial term for coloredcalcic amphiboleswithout confu- Iess than 507o).Nevertheless, a number of previously sion with respect to the precise range shown in classified calcic and alkali amphibolesnow become Figure 3 becausehomblende is always prefixed 'Terro" with sodic--calcicamphiboles. or "magnesio'oin the precise nomenclature. Becauseofthe sfiong desire,especially (but not solely) End.members expressedby mea:norphic petologisK, to retain the distinction of greenactinolite from colorlesstemolite" Richterite Na(CaNa)Mg5Si8Oz(OII)2 the suMivisions hemolite, actinolite,fe,lro-actinolite of Ferrorichterite Na(CaNa)Fe2*5SrsOz(OH)z IMA 78 areretained, as shownin Figure 3. Winchite n(CaNa)Mga(A1,Fe!)SfuO22(OII)2 Ferrowinchite n(caNa)F*+a(Al,Fd*)Siso22(oll)2 End rnembers Barroisite n(CaNa)Mg3AlFesSi?AlO22(OI{)2 Fenobaroisite n(caNa)FeP*3AlFd*Si7Alo22(oI{)2 Tremolite trCa2N{g5SlsO22(OH)2 Aluminobarroisite n(CaNa)Mg3Al2Si7AlO22(OII)2 Ferro-actinolite trCazFeP*sSiaOu(Oez Alumino-ferrobarroisite Edenite NaCa2Mg5SiTAlOnOWz n(CaNa)Fd*3Al2Si7AlO22(OID2 Ferro-edenite NaCa2Fd+5Si7AlOn(OtDz Ferribarroisite n(CaNa)Mg3Fe3+2SizAlO22(OII)2 Pargasite NaCa2(MgaAl)Si6Al2O22(OII)2Ferri-ferrobarroisite Ferropargasite [email protected]'l)Si6Al2o22(oII)2 n(caNa)FeP+3Fe$2Si 7Alo n(olt2 228 THBcANADIANMTNERALocIST Magnesiokatophorite Magnesiotaramite Na(CaNa)Mga(Al,Fd")Si?AlOz(oII)z Na(CaNa)Mga"AlFelSi6Al2O22(oIo2 Katophorite Na(CaNa)Fd*aialne3*)SirAlOo(OID, Taramite Na(CaNa)Fe*3AlFe3*Si6Al2On(OWz calcicamphiboles DiagramParameters: Cas 2 1.50; (Na + K)1> 0.50 1.0 pargaslte (vlAt> Fecf) edenile kaersutite ola magnesiohastingsite o lJ- (vlAt < Fee.) I ;0.5 fenopargasite b, (vlAl E feno-edenite > Fg.e|) sadanagaite lenokaersutite hastingslte (vrAl < FE3+) r,lrlrl 6.0 5.0 6.0 zs .o o.s 5.5 4.5 6.5 5.5 Si in formula Si in formula Parameters: > 1.50;(Na + K)n< 0.50) CaA < 0.50 CaA> 0.50 1.0 tremolite 0.9 cannilloite actinolite magnesiohomblende tschermakite + (\I o tJ- Final namesrequire the relevant J prefixeswhich arelisted in ;0.5 Table I andmaY oPtionallY = includethe modifiersthat are o) feno- found in Table2. fenohomblende fenotschermakite actinolte ,!t : sYmbolsindicate the locations ofend I r' t memberformulae 0.0 listed in the text 6'0 8.0 7.5 7'o 6.5 5.5 Si in formula Ftc. 3. Classificationofthe calcic amphiboles. NOMENCI..4,TURE OF AMPHIBOLES 229 Alumino-maglesiotaramite Limitsfor the we of namzsof end mzmbers Na(CaNa)MgAl2Si6,Al2O22(OtD2 Aluminotaramite Na(CaNa)Fd+3Al2Si6Al2O22(oIO2 Theseare summarizedin Figure4 with respectto Si, Ferri-magnesiotaramife (Na + K),aand Mg/(Mg + Fd*). Alumino and ferri are Na(CaNa)MgFe&2Si6Al2O22(OlI)2again restrictedto uAl > 1.00 and Fd* > 1.00, being Fenitaramile Na(CaNa)FeP+3Fe&zSi6Al2O22(oII)250Vo of the normal maximun of 2R!6.sites. sodic-calcicamphiboles DlagrarnParameters: (Na+ K)a> 0.50;(Ca + Nas)> 1.00;0.50 < NaB< 1.50 1.0 richterlte t I raYr magneslotaramlte + No ll. J ;0.5 = ot feno katophorite taramite rlchterits 0.0 8.0 7.5 7.o 6.5 6.0 5.5 Si in formula Diagnm Parameters: (Na+K)1<0.50; (Ca+ Naa) > 1.00;0.50 < Nas< 1.50 1.0 - wlnchlte banoislte (\I 0' tl. Final namesrequire the relevant .L prefixes which are liscedin ;0.5 Table 1 and may optionally = include the modifion that are o) feno found in Table 2. fenobanoislte winchile , rr t : symbols indicate the locations ofend l ' t memberformulae 0.0 listed in the text" 8.0 7.5 7.0 6.5 Si in formula FIc. 4. Classificationof the sodio-calcicamphiboles. 230 THB CANADIAN MINERALOGIST Mg/(Mg + Fe2*) P 9- (tt o 9D o o o (oE. il a 3 N A :.r d -('l u*ss t 3 s$$Ei o d ! ! d i z !t :.1 @ o I Md(Mg+ Fe2*) irr .9 R o 0a irr (ct + @ + 'n F b ^!t s F o + D N .=3 t o + E CL + t o t -, rd{g It 9) f D j r^J s$a P ln =a ctr 5' P p JI o o o o = ?6' ?q ^osa s- a 9-t 5 iit td >6' 6' pJb ^ j rvg4 g, I id Y€. T< TY: %€ ?,6 3 -eS rd ?E $d E o d o o o N. (tt Mg/(Mg+ Mn2*1 R P o I c) ttt N P sil o x o g.N 3s o de J= E4€EqJdY J= { V@ cai-n JJ 5 ?r,o o q: n3 3 11 (a s-n Ln+ !ro ei(o+ o+ =r3i= P (tl VN J"h \t NOMENCLATT'RB OF AMPHIBOLES 23r sodicamphiboles DiagramParameters: Nas > 1.50;(Na + K)a > 0.50; (Mg + Fe2++ Mn2+)< 2.5; Li> 0.5 (Mg or Fez+1>Mn2+ | tMg or Mn2+)> Fez+ 1.0 1.0 leakeite leakeite CI (I) Fe3+> lvlAt or Mn3+l' f iFeai> [vlAl or Mn3+lr II (\l + c t') + 3 o.s or0.5 E, = b) ferroleakeite komite (Fe&|>tAl or tvtn&l) iMnet2 lvlalorp"3*r' 0.0 0.0 8.0 7.5 7.0 8.0 7.5 7.0 Si in formula Si in formula DiagramParameters: Nas > 1.50;(Na + K)1) 0.50; (Mg + Fez+* p1n2+)< 2.5i Li< 0.5 (Mgor Mn2+)> Fe2+ 1.0 f cir c Final namesrequire the relevant + prefixes which arelisted in or 0.5 Table I and may optionally include the modifiers that are b, found in Table 2. E ungareftiilei t tr r : symbolsindicate (MngF> [vlAtor Fes+l' thelocations of end l tl memberformulae listed in the text. 0.0 7.5 Siinformula 7.0 tidealformula is freeof OH,F,C|;the anionconfiguration is: ...O2202 Flc. 5b.Classification of thesodic amphiboles with (Mg+ Fe?*+ Mn *) <25 apfu, 232 TIIE CANADIAN MINERALOGIST SoDIcArtptmolFs Magnesio-anthophyllite = anthophyllite Sodium-anthophyllite = sodicanthophyllite - This group is defined to include monoclinic amphi- Magnesio-gedrite gedrite = bolesin which Nae2 1.50.The deeiled classificationis Sodiumgedrite sodicgedrite = shownin Figures5a and 5b. Apart from revision of the Magnesio-holmquistite holmquistite Magnesio- boundaryat Nas ) 1.50 insteadof Nap ) 1.34, and the = cummingtonite abolition of crossite so that the 50Vo division is cummingtonite Tirodite = manganocummingtonite followed, the principal changesaxe the infroduction of Dannemorite = manganogrunerite nybtiite, with Si close to 7, as approvedin 1981 (Ungarettiet al. L98I), fenic-nybii'ite(instead Magnesio- of thepre- = viously abandoned'anophorite"),leakeite (Hawthome clinoholmquistite clinoholmquistite Crossite = glaucophaneor et aL L992), ferroleakeite (Hawthome et al. L996a), ferroglaucophaneor kornite (Armbruster et al. 1993), and ungarettiite (Hawthorneet al. L995). magnesioriebeckiteor riebeckite Tremolitic homblende = magnesiohomblende End,memhers Actinolitic hornblende = magnesiohornblende Ferro-actinolitic Glaucophane trNa2(Mg3AlrSisO2dOH)2 hornblende = ferrohomblende Ferroglaucophane nNaz@d+lAldSi8O22(OII)2 Tschermakitic Magnesioriebeckite sNaz(MgfelJStOz(OII)z hornblende = tschermakite Riebeckite trNa2(Fep+3Fe3+)SrsOz(OH)zFerro-tschermakitic Eckermannite NaNaz(MgaAl)Si8O22(OII)2 hornblende = ferrotschermakite Ferro-eckermannite NaNaz@d++Al)Si8O22(OI{)2Edenitic hornblende = edenite Magnesio-arfvedsonite NaNa2(MgaFe3+)SisO22(OII)2Ferro-edenitic Arfvedsonite NaNaz(Fd+lFe?*)SisO22(OIt2 hornblende = ferro-edenite Kozulite NaNazMnnGdt,Al)SisO22(OII)2 Pargasitichornblende = pargasito Nybbite NaNaz(Me3,Al)Si7AlO22(OII)2Ferroanpargasitic = pargasiteor Ferronybdite NaNaaGePrrAl)Si7AlO22(OfD2 homblende ferropargasite Ferric-nybtiite NaNa2(Mg3Fe3+)Si7AlO22(OII)2Ferro-pargasitic Ferric-ferronybdite NaNazGd"gFe&rSi7AlO22(OII)2 homblende = ferropargasite Leakeite NaNa2(Mg2Fe3*2Li)Si8O22(OtD2Ferroanpargasite = pargasiteor Fenoleakeite NaNa2(Fd*2Fe$"Li)Si8O22(OII)2 ferropargasite Kornite (Na,K)Naz(MgzMfi2Li)Si8O22(OID2 Silicic edenite = edenite Ungarettiite NaNa2(Mn2*2VIn3+z)SirOzzOzSilicic ferro-edenite = ferro-edenite Magnesio-hastingsitic hornblende = magnesiohastingsite Limits the we of namesof end members for Magnesianhastingsitic = magnesiohastingsiteor hornblende hastingsite Theseare summarLedin Figure 5 with respectto Si, Hastingsitichornblende = hastingsite (Na + K)a and Mg(Mg + Fd*), Li and Mn parameters. = ma$tesiohastingsiteor \'rAl), Magnesian6astingsite Kozulite requiresMn2+ > (Fe2' + Fe3*+ Mg + hastingsite with uAl or Fe3+> Ivln3*,Li < 0.5. Ungarettiitehas both Mn2+and Mfi > (Fd* + Mg + Fe3*+ uAl), with Li < REFERE}.{CES 0.5 and (OH + F + Cl) < 1.([. Leakeite and komite require Mg(Mg + Fe2*)> 0.50, Li ) 0.50, with Fe3"> Atvrtrottr, J.W., BDeAux, R.A., Buorl K.W. & Nrcuols, Mn3* in leakeite, and Fe$ < Mn3" in kornite. Ferric- vIAl, M.C. (1995):Handbook of Mineralogy 2(1). Mineral Data nybtiite meansFe3+ > which should be clearly Publishing,Tucso& Arizona. distinguishedfrom feni (meaningFeh > 1.00),because neither alumino (meaning vIAl > 1.00) nor ferri are Anvnnusrmq T., OBERHANSU,R., Brruremq V. & DxoN, R. usedas prefixesin the sodic amphiboles. (1993): Hennomartiniteand kornite, two new Mn} rich silicates from the Wesselsmine, Kalahari, South Aftica. SchweizMincral. Petrogr, Mitt. 73, 349-355, At4ptmolE NAtvGsRrcouumunn To BE FORMALLY ASANDONED Glttlcnov, F.V., ed. (1981): Minerals: a Handbook. 3(3). Silicateswith Mubipk Clains of Si4 Tetrafudra.Na:tka" Moscow,Russia (in Russ.). The following namesof amphibolesused in IMA 78 are recommendedto be formally abandoned.IMA Dm., W.A., Howu, R.A. & ZussueN,J. (1963):Rock-Form- 78 listed 193 abandonednarnes. ing Mfuzrals.2, Clwin Silicates.l-ongmarc,London, U.K. NOMENCLATURE OF AMPHIBOLES 233 & - (1997): Rock-Forming IMA (198): Nomenclatureof amphiboles,Can Minzral.16, Mtucral* 28. Double-ChainSilicaes, GeologicalSociety 501-520. ofI-ondon (in press). NrctcL E.H. (199): Solid solutionsin mineral nomenclature. ERNsr, W.G. (1968): Arnphibalas.Springer-Verlag, New Cul Mincral. n. 231-234. York N.Y. & MANDARn{o, J.A, (1987): hocedures involving Hewruonre, F.C. (1983):The crystalchemistry of the amphi- the IMA Commission on New Minerals and Mineral boLes.Can MturcraL.21.l7348A. Names, and guidelines on mineral nomenclature.Can Mbpral. ?5.353-377. Orrnrl R., Camuu.o, E., Senoowq N., Zaneru, A., GrucE,J.D. & Asru-sv,P.M. (1995):A new anhydrous Rocr, N.M.S. & LEAre, B.E. (1984): The Intemational amphibolefron the Hoskins mine, Grenfell, New South Mineralogical Association amphibole nomenclature Wales, Australia: description and crystal structure of scheme:computerization and its consequences.Mineral. ungarettiite, NaNa2(Mfi2Mf)SrsO22O2. Am- Mineral. Mag.4E,2lL-2n. ffi.t65-172. Ssnaazan, H., BrNNo, M. & Ozawe, T. (1984): Sadanagaite Uxcanrrn, L. & Gmcs,J.D. (1992): and magtesio-sadanagaite,new silica-poor members of Leakeite, NaNar(MgzFex'zLi)Si8O22(OfD2,a new alkali calcic amphibolefrom Japan..4ozMineral. 69, 46547 l. amphibolefrom the Kajlidongri manganesemine, Jhabua disftic! Madhya Pradesh,lndiu Am, Mineral.77, lll2- Uncenrrr1 L., Srurq D.C. & RossI, G. (1981): Crysfal- n15. chemistry by X-ray struchre refinement and electron micropobe analysisof a seriesof sodic-calcicto alkali- & _ (199ft): A amphibolesfrom the Nyki eclogite pod" Nornay. BzlL new hyper-calcic amphibolevdth Ca at the A site: fluor- Mindral.lM,4$41L cannilloite from Pargas,Finland. Am. Mineral 81, 995- LWz. VBLm.I, D.R., ed. (1981): Amphiboles and other Hydrous Pyriboles- Mineralogy.Rev. Minera.l. 9A.. OmouNr, L., GRrcB J.D. & Czauaxsrc, G.K. (1996a): Fluor-ferro-leakeite, & RBB4 P.H., eds.(1982): Amphiboles: Petrology NaNa2@e*2Fe3*2Li)Si6O22F2,a new alkali amphibolefrom andExperimental Phase Relafions, Rev, Mineral. 9B.. the CanadaPinabete pluton, Quest4 New Mexico, U.SA. Am- M ineral. El, 226-228. Received.Decetnber 22, 1996. 234 APPENDIX1. INFORMATIONCONCERNING THE ETVMOLOGY. THETYPE LOCALITY, AND THE UNIT.CELLPARAMETERS OFTHIRW AMPHIBOLEEND.MEMBERS Actinolite X-ray data(for fluor-snnnilloite):a 9.826,b I7.907,c 5.301A, B 105.41'. Etymology: From the Greek alctin,a ray, and lithos, a Reference:Hawthorne, F.C., Oberti,R., Ungaretti,L. & stone,alluding to the radiatinghabil Grice,J.D. (L996):Am. Mirwral.8l, 995. Type locality: None. X-ray data: a 9.884,b 18.145,c 5.294 A, B tO+.2" Clinohdmquistite [powder-diffraction file (PDD 25-157 on specimen from Sobotin,Czech Republic)1. Etymology: Named as the monoclinic polymorph of References:Kirwan, R. (1794): Elemcntsof Mineral- holnquistite. ogy L, L67(actynolits). Moffied by Dana J.D. (1837): Type locality: Golzy,Sayany Mounfin, Siberi4 Russia. SystematicMineralo gy (1,s1ed.), 309. X-ray data:a 9.80,b 17.83, c 5.30A, p 109.10'(PDF 25498 ot specimenfrom Siberia,Russia). Anthophyllite References:Ginzburg LV. (1965):Trudy MineraL Muz Akad.Nailk SSSR16,73. Defned by kalre, B.E.(1978): Etymology: The nameis derivedfrom thel-ain antho- Can.Mineral. 16,511. Formsa serieswith magnesio- pltyllutn, clovg referring to its characteristicbrown clinoholmquistiteand ferro-clinoholmquistite. color. Type locatity:Described by Schumacher(1801, p. 96) Cummingtonite as being from the Kongsbergarca, Norway, the exact locaiity being kept secret,but later (Miiller 1825) de- Etymology: Namedafter the discoverylocality. scribed it as being from KjennerudvannLake near Type locality: Cummington,Massachusetts, U.S.A. Kongsberg. X-ray data:a 9.534,b 18.231,c 5.3235A, B 101.97' X-ray data:a 78.5,b 17.9,c 5.28 A (PDF 9455 on (PDF 31-636 on specimenfrom Wabush iron forma- specimenftom Georgi4 U.S.A.). tion, Labrador,Canada). References:M6ller, N.B. (1825):Magazinfor Natur- References:Dewey, C. (18%[):Am. J. ,lci. 8, 58. vedensl Arftedsonite Etymology: Namedafter H. von Eckermann. Type locality: Norra Kfirr, Sweden. Etymology: Namedafter J.A. Arfvedson. X-ray data:a9.7652, b I7.892,c 5.284A, B tO:.tOS' Type locality: Kangerdluarsuk,Greenland. (PDF 20-386 on syntheticmaterial). X-ray data:a 9.94,b L8.L7,c 5.34 A. p 104.40'(pDF References:Adamson, O.J. (1942): Geol.Fdren Stock- L4633 on specimenfrom Nunarsuatsiak,Greenland). holm Fdrh. 4,329. Seealso Adamson,O.J. (L944): References:Brookg HJ. (1823):AwL Phil.2L (2nd ser., GeoL Fdrea StockhnlmFdrh 66,194). Deflned by vol. 5),381 (arfwedsonite).Amended by T. Thomson Leake,B.E. (1978):Can MineraL16, 515. (1836): Outlinesof Minzralogy, Geology,and MineraJ Analysisl,483. Edenite Balroisiie Etymology: Namedafter the discoverylocality. Type locality: Eden @denville),New York, U.S.A. Etymology: Origin of namenot found. X-ray data:a 9.837,b 17.954,c 5.307A, B tOS.tA' Type locality: Not haced. (PDF 23-1405 on specimenfrom Fra::klin Furnace, References:Murgoci, G. (L922): C.R.Acad- Sci.Paris New Jersey,U.S.A.). 175L,373 and 426. Definedby Leake,B.E. (1978): References:Not analyzedin original description.Two Can.Mineral. L6,5L4. analysesof topotype material reportedby C.F. Ram- melsberg(1858): Ann Phys.Chem" (Pogg.) 103,44L, Cannilloite andby Hawes,G.W. (1878) : Aru I. Sci. 116,397, drffer considerably,and neitherfalls within the edeniterange Etymology: Namedafter Elio Cannillo of Pavi4 Italy. of Leake,B.E. (1978): Can Mtueral 16, 512). The Type locality: Pargas,Finland. currentdefinition was proposedby Sundius,N. (1946): Arsbok Sver.Geol. Undzrs.40(4).Composition nearest quistite.Defined by Leake,B.E. (1978): Can.Mineral, to the endmember may be that of lrake, B.E. (1971): 16,511. Minzral. Mag.38,405. Hornblende Gedrite Etymology: The nameis from the Germ4l mining term Etym.ology:Named after the discoverylocality. hom,hom, andbknden, to dazzle. Type locality: H6asValley, nearGbdre, France. Reference:The use of the term hornblende and its X-ray data:a 18.594,b 17.890,c 5.3M A Gpf t:- relationshipto other calcic amphiboleswas discussed 506 on specimenfrom Grafton,Odord County,Maine, by Deer et al. (1963): Rock-FormingMbrcrals. 2. u.s.A.). Chain Silicates.Longmans, London (p.265). Defi:red References:Dufr6noy, A. (1836):Ann. Mines,s€r.3, by Leake,B.E. (1978):Can Mineral. 16,512-513. 10, 582.Defined by Irake, B.E. (1978):Can. Mineral. 16,510. Kaersufite Glaucophane Etymology: Namedafter the discoverylocality. Type locality: Kaersut Umanaksfior4 Greenland. Etymology: From the GreekgLauleos, bluish green, and X-raydata: a9.83, b !7.89,c 530 A, p 105.18"(PDF phaines thai, to appear. 17-478 on specimenfrom Boulder pam, Arizona, Type locality: Syra Cyclades,Greece. u.s.A.). X-ray data:a 9.595,b 17.798,c 5.307A, B 10e.66" References:Lorenzen, J. (1884): Medd. Gr0nland 7, (PDF 20453 on specimenfrom SebastopolauaArangte, 27. Defined and grven speciesstatus by Leake, B.E. California U.S.A. Seealso PDF 15-58 and 20-616. (1978):Can Mineral 16,5L3. Reference: Hausman, J.F.L. (1845): Gel. Kdn Ges. (Glaukophan). Wiss.Gdxingen, 125 Katophorite Grunerite Etymology: From the Greek lcataphora,a rushing down, in referencsto its volcanic origin. Etymology: Namedafter E.L. Gruner. Type locality: ChristianaDistrict (now Oslo), Norway. Type locality: Collobridres,Var, France. References:Brdgger, W.C. (1894): Die Eruptivgest. X-ray data:a9.57,b 18.22,c 5.33 A fi-745 on eDF Kristianiagebietes,Slcr. Vid-Selsk I, Matb-nanr. Kl 4, specimenfrom White Lake, Labrador,Canada), 27. Frequentlyspelled catophorite,and other variants, References:Described by Gruner, E.L. (1847): C.R. but the acceptedIMA spelling is katophorite.Defined Acad- Sci.U,794, but namedby KenngottA. (1853): by Leake,B.E. (1978):Can. Mineral. 16,5I4. Mohs'scheMineral. Syst, 69. Definedby kake, B.E. (1978):Can Mineral. 16, 511. Kornite Hastingsite Etymology: Na:neda.fter H. Korn. Etym.ology:Named after the discoverylocality. Type locality: Wessels mine, Kalahari Manganese Type locality: HastingsCounty, Ontario, Canada. Fields, SouthAfrica" X-ray data:a 9.907,b 18.023,c 5.278A, p toS.oSS' X-ray data: a 9.94(l), b L7.80(2),c 5.302@)A, F (PDF 20-378 on specimenfrom Dashkesan,Transcau- ro5.52". casi4 Russia.See also PDF 20469). Reference:Armbruster, T., Oberhiinsli,R., Bermanec, References:Adams, F.D. & Hanington,B.J. (1896): V. & Dixon, R. (1993): Schweiz Mineral. Petrogr. Am- J. Sci.LSt,2L2; Adams,F.D. & Harringlon,B.J. Mitt.73,349. (1896):Can. Rec. Sci. 7, 81. Definedby kake" B.E. (1978):Can- Minzral. 16, 513). Kozulitc Holmquistite Etymology: Namedafter S. Kozu. Type locality: Tanohatamine, Iwate hefecture, Japan. Etymology: Namedafter P.J.Holnquist. x-ray dara:,a9.99L, b l8.Ll, c 530 A, p 104.6"(PDF Type locality: Utti, Stockholn, Sweden. 25-850). X-ray data:a 18.30,b I7.69,c 5.30A @DF 13401 on References:Nambu, M., Tanida" K. & Kitamura T. specimenfrom Barraute,Quebec, Canada). (1969):J. Japan Assoc.Mineral. Petrogr. Econ. Geol. References:Qgann, A. (1913):Sitz HeidelbergAkad. 62,311.Defined by kake, B.E. (1978):Can Mineral. Wiss.,Abt. 4 4bh.,23. Dimorphouswith clinoholm- 16,515. 236 TIIE CANADIAN MINERALOGIST Leakeite Sadanagaite Etymology: Namedafter B.E. Leake. Etymology: Na:nedafter R. Sadanaga- Type locality: Ikjlidongi manganesemine, Jhabua Type locality: Yuge and Myojin islands,Japan. district, MadhyaPradesh, India. X-ray data:a9.922, b L8.03,c 5.352A, B 105.30". X-ray data;a 9.822,b 17.836,c 5.286A, p to+.lZ'. Reference:Shimazaki, H., Bunno, M. & Ozawa"T. (1984): Reference:Hawthorne, F.C., Oberti,R., Ungaretti,L. & Am-Mineral. 89, 465. Grice,J.D. (1992):Am. MineraLTT,lll2. Taramiie Nybiiite Etymology: Namedafter the discoverylocality. Type locality: Walitarama,Mariupol, Ukraine. Etymology: Namedafter the discoverylocality. X-raydara: a9.952,, 18.101,c 5.322,p 105.45'(PDF Type locality: Nybi!, Nordford, Norway. 20-734 on specimenof potassiantaramite from Mbozi (L98L), X-ray data: In Ungaretti et al. X-ray data are complex,Tanzania). glven for many specimens, a single and "type" speci- References:Morozewicz, J. (L923): Spratu.Polsk Inst. men was not distinguished. Geol., BulI. Serv. G6ol. Pologne 2, 6. Redefinedby Reference:Ungaretti, L., Smith, D.C. & Rossi, G. Leake,B.E. (1978):Can Mineral 16,5L4. (1981):BulL Mindral. lM,,100. Tremolite Pargasite Etymology: Namedafter the discoverylocality. Etymology: Namedafter the discoverylocality. Type locality: Val Tremol4 St. Goufard, Switzerland. Type locality: Pargas,Finland. X-ray data:a9.84, b 18.02,c 5.n L, p [email protected]' (PDF X-ray data:a 9.870,, 18.006,c 5.3C0A, p tOS.+:" L3437 on specimenfrom San Gotardo, Switzerland (PDF23-1406, and PDF 41-1430on syntheticmaterial). and PDF 3L-L285on syntheticmaterial). References:Von Steinheil,F. (18L4)nTasch. Mineral. References:Pini, E. (1796)In Saussute,H.-B. (1923): (1815):9(1), 309. The namewas widely used for green Voyagesdans les Alpes 4, sect.). Defined by Irake, hornblende,but was redefinedby Sundius,N. (1946): B.E. (1978):Can Mineral.!6,512. Arsbok Sver. GeoL Und.ers.40,-18, and Leake,B.E. (1978):Can Mineral. L6, 507and 513. Tschermakite Rtchterite Etymology: Named after G. Tschermak Originally describedas a hypothetical"Tschermak molecule". Etymology: Namedafter T. Richter. References:Winchell, A.N. (1945):Ant MturcraL.30, 29. Definedby Leake,B.B. (1978):Can MineraL t6, Type locality: L$ngban,Viirmland, Sweden. 507 arrd5l2. X-ray data:a 9.907,b 17.979,c 5.269A, p IO+.ZS' (PDF 25-808 on syntheticmaterial; see also PDF 3l- Ungarettiite 1284for calcianrichterite, ard25-675 and31-1082 for potassian richterite). Etymology: Namedafter L. Ungarefti. References:An imperfectdescription by Breithaupt,A. Type locality: Hoskinsmine, nearGrenfell, New South (1865):Bergmann Huttewtwnn- Z.A,3&, wasshown Wales,Aushalia- by Sjiigren, H. (1895): BaIL Geol. Inst. Univ. Uppsala X-ray data: a 9.89Q), b l8.M(3), c 5.29Q) A, 2, 7'1.,to be an amphibole. Defined by Irake, B.E. B tM.6(2)'. (1978):Can Mineral, L6,574. Reference:Hawthome, F.C., Obefii, R., Crnnillo, E., Sardone,N. & Zaneni, A. (1995): Am" Mineral E0, Riebeckite 165. Etymology: Namedafter E. Rlebeck. Winchite Type locality: Island of Socofta Indian Ocean. X-ray data:a 9.769,, 18.048,c 5.335A, p tOl.SO" Etymology: Named after H.J. Winch, who found the (PDF 19-1061on specimenfromDoubnrtschq Romania). amphibole. References:Sauer, A. (1888): Z. Deutsch. Geol. Ges. Type locality: Kajlidongri, JhabuaState, India. 40, 138.Defined by Leake,B.E. (1978):Can. Mineral. X-ray data: a 9.834,b 18.062,c 5.300A, p t04.4" 16,515. (PDF20-1390). NOMENCLq,TURE OF AMPHIBOLES 237 References:Fermor, L.L. (1906): Trans.Mining GeoL Gm.mal,Rmmmtcss Inst. India 1, 79, named the amphibole describedin l9M (Geol.Suw. btdia, Rec.31,236). Topotypemate- Ctttncnov, F.V., ed. (1981): Mincrals: a Handbook 3(3). rial found by Leake, 8.E., Farrow, C.M., Chao, F. & Silicateswith Muhiple Clnins of Si-O Tetraludra,Na*u NUyACV.K. (1986):Mineral. Mag.50,174, provedto Moscow, Russia(in Russ.). be very similar in compositionto that originally docu- (1993): Hey's Minzral ftlax. Natural History mentedbyFermorin 1909(Geol. Surv. India, O.AR& A.M. Mem-37, Museumand Chapman& HaI, Iondon, U.K. 149). Dm, W.A., HowE, R.A. & Zusstr4.qN,J. (1963): Rock-Form- ing Mbwrals.2. Chain silicates.Longmans, Iondon, U.K. Editor's note: Readersinterested in the etymology of QM-374). amphibolenames will find more i:rformationin Black- burn, W.H. & DennerLW.H. (1997): Encyclopediaof LsAxr& B.B. (1978): Nomenclatureof amphiboles.Can Mineral Names.Can MineraL, Spec.Publ. t (in press). Mineral.16. 501-520. 238 APPENDIX2. THEESTIMATION OF THE PROPORTION OF FERRICIRON IN THE ELECTRON.MICROPROBEANALYSIS OF AMPHIBOLES JOHNC. SCHI]MACIIERI Institutfi)r Mineralogie-Petrologic-Geochernkder Albert-htdwigs Universitdta.r. Freiburg, Albertstrasse23b, D-791M Freiburg, Germnty INTR.oDUc'iloN formulae can be found in the appendicesof.De'er et aL (1966, L992).The topic of ferric hon estimatesin arn- Mostusers of the amphibolenomenclature will want phiboleshas been discussedby Stout (1972),Robinson to classiff amphibole compositions that have been et al. (1982,p.3-12), Droop (1987),Jacobson (1989), determinedwith the electronmicroprobe, which cannot J.C. Schumacher(1991) andHolland & Blundy (1994). distinguishamong the valencestates of elements.This An example of the recalculationof the results of an situation is unfortunate,because it is clear that most elecffon-microprobeanalysis and the procedureused to amphibolescontain at least some femic iron; see, for estimateminimum andmaximum contents of ferric iron sxamFle,the compilationsof Irake (1968) and Robin- are gtven at the end ofthis appendix. sonet al. (L982). Consequently,the typical user of the amphibolenomenclature will need to es.'mateempiri- EilapruCaLESTNMTES OF FtsRRIC IRON N.I A}IPMOI-ES cally ferric iron contentsof amphiboles. Empirical estimatesof ferric iron are not just poor The basicformaln approximationstlat suffice in the absenceof analytical determinationsof the ratio FeP*lFe&.Empirical esti- Present knowledge of the crystal chemisry of matesyield exactly the sameresults as analyticaldeter- amphibolessuggests that many of them contain essen- minationsof ferric iron, if (1) the analysisis complete tially ideal stoichiometricproportions of 2 (OII) and (total Fe plus all other elements),(2) the analytical 22 O. Theseanions can be rearrangedto give the basis determinations are accurate, and (3) the mineral's of recalculationof an aohydrousformula: 23 O (+ HzO). stoichiomety (ideal anion and cation sums)is known. Calculationof an anhydrousformula on this basisis the In the case of amFhibolesocondition (3) cannot be first basic assumptionnecessary to estimatethe propor- uniquely determined because tle A-site occupancy tion of Fe3*. The ideal cation-sums in amphibole varies. However, knowledge of amphibole stoichio- formulae are not fixed, but can vary between 15 and metry and elementdisftibution can be usedto estimate 16 cations per 23 O (anhydrous).Consequently, it is a rangeofpermissible sfructuralformulae and contents not possibleto ardve at a unique estimationof Fe3+on of ferric iron. the basisof stoichiometry,as can be donefor minerals The most welcome circumstanceswill occur where with fixed ratios ofcations to anions(e.g., pyroxenes or the differencebetween the limiting sffucfirralformulae the ilmenile-hematiteseries). Nevertheless, on the basis is uivial, andthe entirerange plots within the samefield of presentunderstanding of permissibleand usual site- in the classificationscheme. However. there will also occupancies,limits canbe placedon the maximumand be caseswhere the range of stoichiometricallyallow- minimum valuesof ferric iron conlents,and these limits able formulaeis broa4 i.e., whereit spanstwo or more yield a rangeof acceptableformulae. fields in the classificationscheme. Some users of the amphibolenomenclature may considerthis a less than Critical exarninationof electron-microprobedata satisfactorysolution, but until it is possibleto determine ferric iron contentsroutinely with the sameease and The suiability of there.sults of an electron-microprobe convenienceas with the elecnonmicroprobe, empirical analysis of an amphibole for an estimation of Fd* estimate,sare probably the best alternative. requires the evaluation of the all-ferrous-iron anhy- The procedureof estimatingferric iron will require drous formula calculatedon a 23-oxygen-atombasis. at leastone recalculation ofthe all-ferrous-ironanalyti- The site assignmentscan be usedto evalualethe data cal results to a different cafion-sum. Consequently, and these are given in Figure A-1. From the site- familiarity with the calculationof mineral formulae is assignmentdata it is possibleto define the important higbly recommendedfor a fuller understandingof the limits to the stoichiomety (cation subtotals) of the procedurerequired to estimatethe proportion of ferric amphiboles(column 3, Fig. A-1). Acceptableformulae iron. Thoroughdiscussions ofthe calculationofmineral will satisfy all six of thesecrit€ria- Exceedingone or L E-mail add.ress:[email protected] NOMENCI.A,TURE OF AMPHIBOLES 239 more of these limits in stoichiometT indicates that at someof the sites.)These analytical results should not there are problemswith the struchral formula, and the be used for empirical estimatesof the proportion of identity of the unfulfilled condition will suggestthe ferric iron. Note that exce,ptionsdo exist potassium cause. tianian richterite (Oberti et aL L992) has Ti at the (Hawthorne et al. L996) For mineralsthat bearferric iron, the all-ferrous-iron tetahedral sites; cannilloite position structuralformulae will have cation sumsthat are too has one atom of Ca althe A and two Ca atoms at the B (M4) position. Theseexceptions are ftre. high ffor discussion,see J.C. Schumacher(1991) and referencesthereinl. fu amFhiboles,this san result in violation of at least one of the criteria Si 3 8, XCa 3 Minimum and.maximum estimates 15 or X( 3 16 (Frg. A-1). Violations of the other three criteria >Al > 8, >IvIn > 13 and ll.{a 2 15 (Fig. A-1), In many cases,none of the criteria Si ( 8, lCa 3 15 cannot be due to failure to accountfor ferric iron, and and EK S 16 will be exceededby the all-ferrous-iron usually indicatean analyticalproblem (too few cations formula; the minimum estimateof the proportion of Summaryof site assignments and stoichiometric constraints Site and Stoichiometric Correction Occupancy Cation* Umit w si I-sne ffi si <8 ffiffi AI TAI>8 ffi Ti C-site Cr Fe3+ Mg ffiffiNi ffiffi 7n &'jt" W Fe2+ ww Mn IMn ) 13 Ca ICa< 15 WwNa INa> 15 A-site K w tr IK < 16 * cationsarranged according to increasingionic radius (smallesqSi to largest,K) X = cationsubtoal (e.g. XMn = sumof all cationsfrom Sithrough Mn in the list) E = cancyattheA-site Ftc. A-1. Summary of ideal site-assignments,limits of various cation subtotals,and the type of correction (minimum sp maximum) that can be obtainedby calculating the formulae to these stoichiometic limits (after J.C. Schumacher1991). Abbreviations of normalizations:8Si: normalized such that total Si = 8: 8SiAl: normalized such that total Si + Al = 8; l3eCNK: normalizedsuch that the sum of the carionsSi tbroughMn (Le., all cationsexclusive of C4 Na K) = 13; l5eNK: normalizedsuch that the sumof the cationsSi tlrough Ca (i.a., all cationsexclusive of Na, K) = 15; 16CAT: normalizedsuch that the sum ofall cations= 16 (seealso Robinson et al, 1982,p.6-12). 2/+0 Fe3t is given by the all-ferrous-ironformula (i.e.,F* thetical resultsof an analysis(wt%o) and four formulae - 0.000, and the site occupanciesof all-ferrous-iron that are basedon 23 atomsof oxygen.Formulae were formula are all allowable).If one (or more) of the three calculatedfor the two chemicallimits (all iron as FeO criteria Si 3 8, ICa ( 15 and EK 3 16 is exceeded"Fe! or FezO:); the other t\ro are the stoichiomehiclimits may be present and a minimum estimateof its propor- (Frg.A-1) that give the minimum(15eNK) and maxi- tion can be madethat will yield a formula with accept- mum (l3eCNK) estimatesof the proportion of ferric able stoichiomety. The condition that is most greatly iron. All of the stoichiometric limits except XCa S exceededdetermines the basisof the recalculation.For 15 (hereXCa = 15.029)are met by the all-ferrous-fuon example,if Si = 8.005,XCa = L5.030and IK = 15.065, formulA which means that the minimum-ferric-iron then the xSi limit is exceededby 0.@5, and the XCa" formula is grvenby the 15eNK estimate(Table A-1). by 0.030.Since XCa is in grcatestexcess, the minimum Since XtrVInis nearestthe lowest allowable sum,the estimateof the proportion of ferric iron is obtainedby maximum estimatedproportion of ferric iron and the recalculatingthe formula so that >Ca = 15.000(15eNK all-ferric-iron formula are obtainedby recalculatingas estimate,Fig. A-1). before, but in this case,the normalizationmust insure The maximum estimatesof the proportion of ferric that )Nln = 13.000 (here the normalizationfactor is: iron are obtainedfrom the stoichiometic limits XAI ) 13 + 13.2-01.= 0.9848). The minimumvalues for XAl, 8, >Mn ) 13 and xl.{a ) 15 @ig. A-1). The condition XVIn and DrIa are, respectively, 8.000, 13.000 and that is nearestto t}le minimum value of one of these 15.000,and the actualvalues are 9.L39,13.201and snms gives the maximum estimateof ferric iron. For 6.744. example,if XAI = 9.105,X\4n = 13.099and xl.{a = These formulae for the minimum and maximum 15.088,then XAI is exceededby 1.105,Xtrvln, by 0.099, estimatesof the proportion of ferric iron can be calcu- and Z}.{a"by 0.088.The D.{a is nearestthe minimrrm lated in either of two ways: (1) by normalizing the value, and recalculating the formula so that XNa = proportion of all cationsof the all-ferrous-ironformula 15.000(15eK estimate,Fig. A-1) will give the formula that were calculatedon a 23-oxygen-atombasis, such with the maximumproportion of ferric iron. that XCa = 15.000and Xr4n = 13.000(1a., number of cationsof eachelement multiplied by 15 + XCa or 13 + Recalculationof theforrnulnc ItrVIn;here, 15 + 15.029= 0.9981,and 13 * 1324L = 0.9848,respectively), or (2) by using the normalization The recalculation procedure is describedstep-by- factor to determinethe new sum of cations and then step at the end of this discussion,but some general recalculatingthe entire formula on cationbases that set aspectsare discussedhere. Table A-1 lists the hypo- >Ca = 15.000and XvIn = 13.000.The secondmethod requiresmore calculation,but J.C. Schumacher(1991) has shown that this method leads to fewer rounding TABIT A-I. A HYPOTTIETICAL COMPOSMON OF AMPHIBOI.E errorsthan normalizingthe cationsin the formulabased on 23 atomsof oxygen. AnalyslB Formulae (wt%) The formula obtained from either recalculation Alt Atl method will have less than 23 atoms of oxygen. The Fenous 15eNK 13eCNK Fenic proportion ofcations ofFd* is found by calculatingthe Si02 39.38 si 6.093 6.081 6.000 5.714 numhr of moles of FeO that must be convertedto AlzOa 16.70 Al 1.907 1.919 2.000 2.286 FeO1.5tobring the sum of the oxygen atomsto 23; it FeO 23.v > 8.000 8.000 8.000 8.000 Mgo 4.N equals(23 - IOx) X 2, where XOx is the sum of the CaO 11.03 AI 1.139 1.122 1.000 0.571 oxygen in the normalizedformula (XOx = 2# x 2 + Na2O 2.37 FeSt 0.000 0.088 0.700 2.857 '1.015 1.0t4 1.000 0.952 >R3+x 1.5 + XR2++ >Rl+ x 0.5, whereXR = the sums Total 97.42 of cationswith the samevalence). The numberof moles 5.000 of FeO equal Fo1 - Fd*, where For = total Fe in the Fe24 0.201 0.176 o.ooo o.ooo normalizedformula. Following any recalculation,it is Ca 1.799 1.a24 1.800 1.714 good practice to recheck to seetlat all six stoichio- Na 0.000 0.000 0.200 0.286 metric limits are also satisfiedbv the new formula. >, 2.000 2.000 2.000 2.000 Ca 0.029 0.000 0.000 0.000 Discussionof resultsof the recalculation Na 0.711 0.709 0.500 0.381 Sum 15.740 1s.s00 14.761 The variationin somecation values within theranges of possibleformulae (Table A-1) that are defined by The shuofiral fomulae m basedon the chemicalmd stoichiomeaiclinitr The a[- the chemical and stoichiomefriclimis is comparedin fsDeim fomula Nms rotal Fe 6 FeO,ad the all-fmic-iron fomula mq total Fe 6 Fe2q. The I3€CNK ed l5eNK fomule e b6ed on sloichiomebic Figure A-2. In general,the rangeofpossible formulae linib. S€ text for dtcNion. that are defined bv the stoichiomenic limits will be ul AllferrousFe (chemlcalllmlt) l5eNK (stolchlometrlcllmlt) All ferric Fe l3eCNK l6CAT (chemlcal llmlt) (stolchlometrlc (stolchlometrlc 15eK llmlt) (stolchlometrlcllmlt) 4p- o tr o ot ox qt N oL o. o tr o .J or! Total Cations per 23 Orygens FlG.A-2. Plot of various cation valuesand sumsversus total cations.which illustratesthe continuousvariation of tlese values relative to chemicaland stoichiometriclimits. The stoichiometriclimits aregiven in Figure A-1, andtle valuesare based on the amphibolecomposition given in Table A-1. 242 much ru[rower than the range obtainedfrom the two the amphibolenomenclature is further suMivided. The chemical limits. A diagram like Figure A-1 could be five Cpositions consistofthree "mica-like" positions, constructed for every electron-microprobedata-set, two Mt octahedraand one M3 octahedron and tlvo and, on sucha diagra:4 the rangeof both the chemical "pyroxene-1ike"positions, the M2 octahedra.The and the appropriateset of stoichiometriclimits could cations Al, Fe3*,Ti and Cfi are sfiongly partitioned vary greatly from exam.pleto example. It can be into the IuI2 octahedra.Consequently, an additional i:rferred from Figure A-2 that the rangeof permissible estimateof the maximum amountof ferric iron can be formulae could be, and commonly is, boundedby one obtained if one assume.sthat all the tetrahedraland of the chemical limits and one of the stoichiometric M2 sitpsare completelyfilled with cationsof valences limits. 3+ and 4+. This normalization-factor(lI) can be calcu- The relationshipspmong cation sumsthat are illus- lated by solving the two simultaneousequations forly': trated in Figure A-2 sholv that comparisonof someof (1) N X (Si +Ti + Al + Cr) + Fe3*= 10,which describes the possiblenormalization-factors, which are obtained the desiredresulting stoichiometry, and (2) Fe3+= (23 - from the stoichiometriclimits, canbe usedto (1) check 23 x 1,1)X 2, which gives the amountof ferric iron for the applicability of a specificestimate of the proportion this normalization.The solution is: N = 36/(46- Si - Ti of ferric iron, and (2) detemine limits, chemical or - Al - Cr), where Si, Ti, Al and Cr are the amountsof stoichiometric,that give the minimum and maximum these cations in the all-fenous-iron formula. For the estimatesof the proportion of ferric iron. To accom- analytical results in Table A-1, this normalization- plish this, all the normalization-factors for all factor, hereabbreviated 10fe&, isD.977,whichis less stoichiometic constraintsand the chemicallimits must than the 0.983 value of the 13eCNK factor, such that 6s s6mFared(Fig. A-l). The normalization-factorsfor the 10Sd* normalizationwill not give the maximum the stoichiometricconstaints, calculatedfrom the all- estimateof the amountof ferric hon in rhis case. ferrous-ironformula using the datain Table A-1, are: Most usersof the nomenclatwewill want to report only a single formula and name for each amphibole Minimum estimateof the proportion of Fd+: amlyzed; consequently,the overriding question is: 8Si= 8/Si=816.093 = 1.313 (1), which correctionshould be used?Unforhrnately, there 16CAT= 16DK = 1611,5.740= 1.017 Q), is no simple rule, and eachgroup of similar analytical all ferrousiron (no change)= 1.000 (3), datamay require individual freatuent. Robinsonet al 15eNK= lllX,a= 1,5/15.A9= 0.998 (4). (1982, p. 11) and J.C. Schumacher(1991, p. 9-10) discussedsome of thesepossibilities for Fe--Mg,calcic, Maximum estimateof the proportion of Fe3+: sodic--calcicand sodic amphiboles in greaterdeta.il. The 10XFe3*correction discussedin the preceding para- = = = l3eCNK 13/2IVIn l3lL3.20I 0.985 (5), graph will not likely be important in Ca-amphiboles, = 15eK= 151D.{a=I511"5.7q 0.953 (6), but in sodic amphibole(a.9., riebeckite, glaucophane), = all ferric iron 0.938 (7), it may commonly yield the maximum estimateof the = = = 8SiAl 8DAl 819.139 0.875 (8). proportion of ferric iron. For the normalizationsthat yield minimum estimates Choosinga single representativeferric-iron-bearing (1 to 4), the recalculation that requires the lowest formula out of the range of possibleformulae requires jusffication nonnalization-factorwill give the minimum estimateof further or additional assumptions.One the proportionof ferric iron. For the normalizationsthat solution is to use the mean value befweenmaximum yield maximumestimates (5 to 8), the recalculationthat and minimrrmcontents of ferric iron (Spear& Kimball requires the largest normalization-factorwill give the 1984). Other solutions can be obtained for resticted maximum estimateof the proportion of feric ir:on.All types of amphibole. For example, R. Schumacher normalizationsthat lie betweenthese values (in this (1991) derived a schemeof normalizationthat yields example,0.998 and 0.985)will give stoichiometrically formilae intermediatebetween maximum- and minimum- acceptableformulae. If any of the normalization-factors ferric-iron formulae for samplesof calcium-saturated for the maximum estimate(5 to 8) is greaterthan any metamorphic hornblende. Her scheme is based on of those for the minimum estimate(1 to 4), then the regression analysis of hornblende compositions for analyticaldata are not suitablefor empiricalestimafions which determinationsof the proportion of ferric and of the proportion of Fe3+.Note that normalization- ferrous iron were available. factors greater than 1.000 or less tlan the normaliza- In general,it will be desirableto determinethe extent tion-factor for the all-ferric-iron formula would vield 1q\r/ffiefu the minimum andmaximum estimations of the imFossibleestimates of theproportion of Fe$, tdatte proportion of ferric iron affectsthe classificationof the beyondthe chemicallimits. amphibole in question by inspecting the formulae of ln additionto the stoichiometricconsffaints listed in both the maximum- and rninimrrm-ferric-ironesti- Figure A-1, anotherconstaint on maximumamount of mates. If the entire range of formulae gives a wide Fe3*can be defined if the C site in the formulation of spectrumof possible names,this should probably at '243 NOMENCI.A,TIJRE OF AMPHIBOLES least be mentionedwherever the amphibole is being provided that the chemical analysisis complete,and described. ideal stoichiomefiy(site occupancy)can be assumed.If theseconditions hold, empirical es.'matesof ferric iron DrvtanoNs rnovr nIE BAsrc AssuvrrnoNs would have an accruacyand precision comparableto those associatedwith a determination of the ratio Incorporation of F and Cl Fe2+^re3+.For amphiboles, stoichiometry cannot be uniquely determined, but various crystal-chemical Both F and Cl may substitutefor (OH) in the amphi- constraintsallow a rangeofpossible formulaethat give bole sfructure,but concentrationsof theseelements are the minimum and maximumcontents of ferric iron. not routinely determined at all electron-microprobe Selectinga single sffucturalformula from the range facilities. Althougb it is highly recommendedthat their ofpossibilities requiresthe applicationof an additional concentations also be determined their presencehas consfraint or a firther assumptionosuch as using the no effect on the procedureof estimationof ferric iron. formula that gives minimum, maximum or the mean ExchangeofF or Cl fo3 OH doesnot changethe total amount of ferric fuon, or applying some petrological number of negative charges (46) in the anhydrous consffaint.In written descriptions,it will be formul4 suchthat the proportionsof cationsrequired to to report the analyticalresults, which enablesothers to gpve4.6 positive chargeswill be independentof the do their own recalculations,and a clear statementof the propofiionsof OH, F or Cl that arepresent. The critical methodand assumptionsthat wereused to calculatethe assumptionis that exactly two anions [OH, F, Cl] are structuralformula reported. presentfor every22 atomsofoxygen. The usersof the IMA amphibolenomenclature ought to explore the formulae to estimatethe minimum and Coupledsubstitutions involving anions maximumamountsof ferric iron. This approachdefines the range of possible formulae and possible narnes. The validity of a basic 23-oxygen-atoma::hydrous Sincesome amphibole names carry specialpetrogenetic formula (i.e., exactlytwo OH + F + Cl) is an underlying significance,care should be takenifthe rangeofpossible assumptionin the procedureto esfimntethe proportion namesis large. of ferric iron in amphiboles.Any variation in these valueswill have a tremendouseffect on the a:nountof WoRm-Tm.oucH ExAMpr-E:Cerrur.enoN ferric iron estimated.The partial replacementof [OH + oF AN AMPHIBOLE FORMTI-A AND AN ESTN4ATE F + Cl] by O in the amphibolestructure is an example oF PRoPoRTIoN OF FhRIC IRONFROM RBSULTS ofthis kind ofvariation, andhas long beenrecogilzed. OF AN EI-ECIRON-MICROPROBE ANALYSIS Amphibolesthat are refened to in numeroustextbooks '"basaltic on mineralogy and optical mineralogy as As an example (Table A-2), the compositionthat hornblende" Qeer et al. 1966), or the kaersutiteend- appearsin Deer et al. (1992, p. 678) was chosen.To memberof the IMA systemof nomenclature,can show simulate analysis with an electron microprobe, the this type of compositionalvariation (see also Dyar et aL ferric iron was recastas fenous iron, and resultsofthe 1993). H2O determinationwere ignored. The ferric iron esti- Intuitively, one would expectanalytical totals to be matewas madeassumin g that 2 (OtI) arepresent rather affectedby variableproportions of O andOH; however, than the 2.L46 suggestedby the actualdetermination of sincethese amphiboles tend to be richer in ferric hon, H2O*.Any discrepanciesin the final decimalplacas of the increasein the sum from the partial exchangeof O the numbersthat appearbelow and in Table A-2 are for OH tendsto be offset by treatingthe larger amounts due to rounding effects. of Fe2O3asFeO. Consequently,even in anhydrous amFhiboleswith a significant proportion of ferric iron, (l) Divide the wtvo of eachconstituent (column 1) by no compelling evidence of these substitutions will the molecular weight of the constituent,to yield the necessarily be seen in the results of the analyses. molecalar proportion of each (column 2) le.g., for Ferric-iron estimalion can still be carried out on com- SiOz:51.63 + 60.085 = 0.859281.Data on the positionswith variableproportions of O andOH, but an molecularweights were taken from Robie et al. (1978). estimateof the H2O and halogen contentswill be an (2) Obtainatomic proportions of the cartons(column 3) essentialadditional requirement. andatornic proportions of oxygen (column 4) by mul- tiplying each molecul.arproportion value by the CoNcr-usrons numberof cationsand oxygenatoms in the onde[e.g., for SiOz:0.85928 x 1 = 0.85928and 0.85928x 2 = Amphiboles typically contain at least some ferric r.7r8s7l. iron, and may contain significant amounts;howevero themost common amlytical metlo4 electron-microprobe Notq If one assumesthat 2 (OID groups are present, analysis, cannot distinguish between valence states. oneatom of orygenis balancedby2 H (1e.,H2O), such The ferric iron contentsof amphibolescan be estimated that the cation chargesare balancedby the remaining 2M TIIE CANADIAN MINERAL@IST TABLE A.2. A WORKED.TI{ROUGH EXAMPLE OF THE CALCI]I.ATION OF TI{E STRUCTTJRALFORMTJLA OFANAMPHIBOLE* 1 2 3 4 5 6 Atomic Atomic €rnionson calions on Molecular )roportlonsrroportionsthe basis of the basisof Wto/o Prooortiong (catlons) (oxvoens) 29 oxvoens 23 oxvoens cot. z x col.z x !vt70 * catlons In orygensin col. 4 x col.3 x mol. wt. odde oxlds 4.45012 8.45012 1.7'1457 n02 0.00 0.00000 0.00000 0.00000 0.00000 0.000 Al2O3 7.39 0.o7248 0.1 4496 o.21744 1.83736 1.22s Cr2Og 0.oo 0.00000 0.00000 0.00000 0.00000 0.000 fto 7.55 0.10509 0.10509 0.10509 0.88799 0.888 rfto o.17 0.00240 o.oo240 o.oo240 0.02025 0.020 tup 18.09 o.44884 o.44884 0.44884 3.79274 3.793 @ 12.32 0.21969 0.21969 0.21969 1.85641 1.856 t{a2o 0.61 0.00984 0.01968 0.00984 0.08317 0.166 t<& 0.00 0.00000 0.00000 0.00000 0.00000 0.000 sum 1.79994 2.72185 23.0000 15.210 Factorfor the recalculationof alomicproportions to 23 O basis:29 + 2.72185= 8.45012 TABLEA-2 (CONTINIJED) 13 ldeal slte idoal slte (15eK) Formula from DHZ 7. Allv 0.739 Allv 0.760 0.839 0.79S 0.804 8.000 sl 7.2401 4.4802 gum f 8.000 8.000 AIVI 0.486 AI 1.2214 1.8321 Alvl 0.462 0.369 0.416 0.410 Fe& 0.000 Ti 0.0000 0.0000 Fe&r 0.133 0.634 0.38S 0.263 0.000 0.0000 0.0000 Cr 0.000 0.000 0.000 0.000 Mg 3.793 Mg 3.781I 3.7818 MS 9.782 9.740 3.761 3.759 Fe2+ 0.721 Fe2+ 0.8854 0.8854 Fe2+ o.624 0.242 0.440 0.618 Mn 0.000 Mn o.0202 o.0202 Mn 0.000 0.015 0.000 0.000 5.000 a 1.85111.8511 gum C 5.000 5.000 5.000 Mg 0.000 Nla 0.1659 0.0829 Mg 0.000 0.000 0.000 0.000 Fe2+ 0.167 K 0.0000 0.0000 Fe+ 0.129 0.000 0.057 0.050 Mn 0.020 6Um 15.1 659 9337 Mn 0.020 0.005 o.420 0.020 q 1.856 o 1.851 1.831 1.841 1.840 l{a 0.000 /,>Ca(@|7, lla 0.000 0.164 0.082 n non 2.043 15+ 15.Ozl3=0.99714 2.000 2.000 2.000 2.000 t{a 0.166 t{a 0.166 0.000 0.083 o.o74 K 0.000 (23-22.93371x2 K 0.000 0.000 0.000 0.000 u. too - 0.1325 0.166 0.000 0.073 0.074 total 15.210 tolal 15.166 15.000 15.083 15.07 1 0.885-0.133 = 0.753 t Takenftom Deer et aI. (192, p. 678). Seetext for a step-by-stepdiscussion of this table. '245 23 atomsofoxygen, which is the basisofthe anhydrous ferric iron can be calculated;if not then no estimation formula (seetext for discussion;it can be shown thar is possible. evenif concentationsof F and Cl havenot beendeter- 'mates (7) Minimum es of the amountof ferric iron mined, the 23-oxygen-atom formula will give the correctformula, as long as OH + F + Cl = 2). The lowest normalization-factor arnong the four (3) Obtain the proportion of the anions based on choices, 8Si, 16CAT, 15eNK and all ferrous iron, yields minimum 23 atoms of oxygen (column 5) by multiplying each determinesthe formula tlat the esti- value in column { by 23 divided by the sum of column mate of the anount of ferric iron. If the factors 8Si" 41e.g.,23+ 2.72185= 8.45012;for SiO2:1.71857 x 16CAT and 15eNK areall greaterthan 1.0000,then the = 8.450L2= 14.522187. all-ferrous-ironformula @e3* 0) is the lower limit. In this example, the 15eNK normalization-factoris the (4) Obtaintle proportion of thc cations on the basisof lowest. 23 atoms of orygen (column 6) by multiplying each To obtain the formula that gives the minimum esti- value in column 3 by 23 + the sum of column 4 le.g., mate of the amountof ferric iron (column 8), multiply for SiO2:0.85928 x 8.45012= 7.261f. the proportion of the cations from column 6 by the ( + Note: Column 6 is the all-ferrous-ironformula of the 15eNK normalization-factor,0.997 L4 15 15.043). amFhibole.Assignment of the cations to sites shows (8) Find the sum of oxygen atoms (22.9337) in the whetherany deviationsfrom ideal stoichiometrycanbe normalizedformula by multiplying each single cation explainedby failure to accountfor ferric iron. value (column 8) by the numberof balancingatoms of = (5) Ideal site-assignments(colr'mn 7) aremade from the oxygen le.g., for 5iO2,7.2N7 x 2 L4.48O2;for = = cation valuesin column 6. The generalprocedure is: AJO15,L.22L4 X 1.5 I.8321;for MgO,3.7818 X 1 3.7818;for NaOo.s,0.1659 X 0.5= 0.08291. (a) the eigltt tetrahedral(7) sites: . place all Si here; if Si < 8, fill the remainingsites (9) The amount of fenic iron quials the amount of with Al. ferrous Fe that must be convertedto bring the total (23 - . if Si + total Al < 8, then place all Si + Al here. oxygenatoms up to 23.T\e amountis 22.9337) x, 2 = 0.L33. @) thzfive octahedral(C) sites (M2, ML, In) . placeAl remainingfrom step(a), Ti, Fd* (initially (10) The new ferrow iron value is the total Fe ftom = 0), and Cr here. In the following order, place column 8 minusthe amountof ferric iron [e.9., 0.885- enoughMg, FeP*and Mn to bring the total to 5. 0.133= 0.7531. . if X(uA{.. Mn) < 5, then place all theseelements here. (11) Recastthe normalizedcations as in step5 (column (c) the two (B) sites (M4) 10). This should yield a formula without violations of . place any Mg, Fd* or Mn and Ca remainingafter the ideal stoichiometry. stop (b) here. Note: Step 11 double-checksthe correchess of the . if X(Mg...Ca)atB <2, filI theremaining sites with calculations.It also is a checkon whethercorrection of Na to bring the total to 2. the initial stoichiometic violation will produceanother (d) the sinsle large (A) site [here,insuffi.cient cations to filI 7or Ccould resultftom . place any remainingNa and K here. the 15eNK nonnalization.Such analvticaldata cannot (6) Evalu*ing the stuctural formula If any site hasless than their ideal values(7 = 8.0@, TABLE A-3. CALCULATION OF TtlE NORMALIZA*TION-FAS|ORS C = 5.000,B = 2.000,A = 0 to 1.000),then an estimate of the proportion of ferric iron is either impossibleor M€&od of NmsL C€lgulali@ &ffi only possiblewilh additionalconstraining information. This sifirationcould alsoindicate an analyticalproblem. Calczlalow of the athaated tuhtlM @tott offetlc tron The suitability of the analytical data for an estima- 8St E+St E+7261 l.lolt tion of the of ferric iron and the normaliza- l@AT l6+X( 16+15210 1.0519 tions that yield the maximum 41d minimum estimates all ferrca iotr 1.0000 l5eNK l5:lca l5r 15.043 0.9971. of ferric iron can be determinedby calculafing the normalization-factorsfor all the various stoichiometric Cabndfo8 of tb estlnded ndt tM motx offu tr@ and chemicallimits. Theseare given in Table A-3 and lsoK l5+D{a l5 + t5.210 0.9862i l3eCNK t3+XVn 13+ 13.187 0.9858 are obtainedfrom columns6 or 7. all fenic ion 23 + [23+ (0.5x Fen)] 23 + 23.444 0.9&1 If the normalization-factorsbased on 8Si, 16CAT l08d' 36+(46-Si-Al-Ti-cr) 36+37.5141 0,9596 SsiAI SrlAI I r 8.486 0,9427 and 15eNK are greaterthan the normalization-factors basedon 8SiAl, 15eK, 10XFe3*and l3eCNK, then an . hdiers &e nomalizdim &d yield ths ntnintn ed @imm estim&d @oub estimate of a minimum and a marimum amount of of fnio ircD, 6p6itively. 246 TI{E CANADIAN MINERALOGIST be usedto estimalethe proportionof ferric iron (unfor- IIAwrnoRNE,F.C., OsERTr,R., Uncanrm, L. & GRICE,J.D. tunately,a lot of calculationis involved in deterrnining (1996): A new hyper-calcic amphibolewith Ca atthe A this)]. site: fluor-cannilloite from Pargas,Finland. Am- Mineral. 81,995-1002. (12) Maximum estimatesof the proportionof ferric iron HoLAND, T. & BLuNDy, J. (1994): Non-ideal interactions The largest normalization-factor among the four in calcic amphiboles and their bearing on amphibole- choiceso8SiAl, 15eK, 13eCNK and all ferric iron, plagioclasethemometry. Contrib, MinzraL Petrol. l'16, determinesthe formula that yields the maximum esti- 433447. mate of the proportion of ferric iron. If the factors 8SiAl, 15eK and l3eCNK are all less than the all- IAcoBsoN, C.E. (1989): Estimation of Fe$ ftom electron ferric-iron value, then the all-ferric-iron formula will microprobe analyses:observations on calcic amphibole give the maximumamount of Fek. In tlis example,the and chlorite. J. Metamorph Geol, 7,547-51'3. 15eK normalization-factoris the largest, and can be used to give the formula with the maximum amount LEAre, B.E. (1968): A catalog of analyzedcalciferous and with their nomencla- of Fd+. subcalciferousamphiboles together ture and associatedminerals. GeoI. Soc. Am., Spec.Pap. To obtain the forrnula that gives the maximum esti- 9E. mated amountof ferric iron (column 1l), repeatsteps 7 through l0 using the 15eK normalization-factor OsERT,R., UNcans'nl L., Camulo, E. & HawtonNe, F.C. 0.98621(15+ 15.210). (L9/2): T\e behaviour of Ti in amphiboles.I. Four- and six-coordinateTi in richterite.Ezr. J. Mhrcral. 4" 425439, (13) Averageof the maximum4ad minimum sstimated amountof ferric iron Rorn, R.A., I{nmcwav, B.S. & H$nR, J.R (1978): Ther- propertiesof ninerals and related substances gives modynamic To obtain the formula that the averageof the at298.LSK and I bar (lSPascals) pressureand ar higher maximum and minimum estimatedamount of ferric temperatures.U.S, Geol. Sarv,,Bull, 1452. iron (columns 10 and l1), repeat steps7 tbrough 10 usingthe averageof the normalization-factorsthat were RoBtr\soN,P., SpBan,F.S., SaruMAcuR, J.C., LARD, J., obtainedin steps7 and 12.This normalization-factoris KLm.r,C., EvANs,B.W' & Dooux, BI. (1982):Phase 0.99167[(0.99714 + 0.98621)+ 2]. relations of metamo4)hicamphiboles: natuml occurence and theory..In Anphibolas and other HydrousPlriboles - (14) The actual formula (column 12) given in Deer Mineralogy (D.R. Veblen & P.H. Ribbe, eds.). fteu. et al. (L992) lies approximatelybetween the minimum MineraL9B,1,-227. estimate(15eNK) in column 10 andmaximum estimate (15eK)in column11, but is nearcrthe minimum. SctuMAcHE&J.C. (1991): Empirical ferric iron corrections: necessity,assumptions, and effects on selectedgeofhermo- RmsRB.{cFs bnometets.Mineral Mag.55, 3-18. DEERW.A., HowE" R.A. & ZussMaNI . (I966)tAn Introdilr- Scruuacm, R. (1991): Compositionsand phaserelations of , , in epidote- and clinopyroxene-bearing tion to thc Rock-Forming Minerals. Longman Group calcic amphiboles andlower granulitefacies, central Limit€4 London, U.K. rocks ofthe amphibolite Massachusetts.USA. Contrib. MineraL PetroL 1ffi. 196- zLt. & -(1992): An Introductian to the Rock-FormingMinerals (2nd ed.). Longman Group - UKLimite4 Essex,U.K. SpeA&F.S. & Iturmeu. C. (1984):RECAMP a FORTRAN IV program for estimating Fe+ contentsin amphiboles. -325. DRooP,G.T.R. (1987):A generalequation for estimatingFe& Comptu.Geosci. 10, 317 concentrations in ferronagnesian silicates and oxides from micropobe analyses,using stoichiometric criteria- Srour, J.H. (1972):Phase pemlogy andmineral chemistryof Mineral. Mag. 51, 43L435. coexistingamphiboles from Telemad<,Norway. J. PetroL 13.99-145. Dvan,M.D., Macrwu-r. SJ.,McGuns, A.V., Cnoss,L.R.& Roarnrsor, J.D. (1993): Crystal chemistryof Fe3*and H* in mantle kaersutite:implications for mantle meta$ona- tism..4n Mturcral.78. 968-Y79. Receive d December 22. I 996.