61. Tlrc Catwdian M ineral ogi st Vol. 34, pp.6lJ2 (1996) CLINOAilACAMITE,A NEW POLYMORPHOF Gur(OHl3Cl, AND ITS RELAflONSHIPTO PARATACAMITEAND 'ANARAKITE"* JOHNL. JAMBOR Department of Earth Sciences, University of Waterlao, Waterloo, Ontario N2L 3GI JOHNE. DUTRZAC CANMET,Deparnnent of Naaral ResourcesCananq 555 Booth Street, Ottawa, Ontaria KIA OGj ANDREW C. ROBERTS GeologicalSurvey of Cananq601 Booth Street, Otawa" Owaria KIA 088 JOELD. GRICE ResearchDivisiou CatadianMuseurn of Naure, Ottatva,Ontaria KIP 6P4 JANT. SZYMA(SKI CANMET,Depamnent of NaturalResources Canad4 555 Booth Street, Ottawo" Ontario KIA 0GI ABSTRA T The new mineral clinoatacamiteis a polmorph of Cu2(OII)3C| othen are botallackite (monoclinic), atacamite(ortho- rhornbic),an{ possiblyparatacamite (rhombohedral). Clinoatacanite is monoclinic, spacegroup P21ln,a 6.157(2),b 6.814Q), c 9.104(5) A, p 99.65(4)", which is transformableto a pseudorhombohedralcell approximating that of paxatacamite. Clinoatacamitehas been found in specimensfrom severallocalities, aad coexistswith paratacamitein the holotype specimenof p,aralacamite.The two minerals are not readily distinguishedexcept by optical and X-ray methods:paratacamite is uniaxial negative, whereasclinoatacamite is biaxht negative, 2V@75(5f . Strongestlines of the X-ray powder paltern of clino- aracamireld n A(D@k[)]are 5.47(100)(T0l,0Ll),2.887(40X121J03),2.767(60)81.1),2.742Q0)(0r3,202),2.266(@)Q20), 2.243(50)(004),and L.7M(5Q82a,040). Clinoatacamiteis readily synthesizedand a seriesof experimentswas conductedto promotethe uptakeof Zn and duplicatethe formula of the dubiousmineral "anarakite" (CuZn)2(OI{)3C1.Generally, products with more than about6 mol%o"7iproved to be hexagonal,i.e., nrcranpaatacamite, as did specimensof "anarakite"fron fhe type locality. Holotype paratacamitecontains 2-3 wtVo Zn, andit seemsthat r€placementof Cu by small amountsof another cation, such as Ni or Zn, is eitler favorable or essentialto stabilize the rhombohedral(pantacamit€) structure.The Powder Diffraction File standardfor paratacamite(25-l4n) is that of clinoatacamiterather than paratacamite. Keyword*: clinoatacamite,new mineral species,paratacamite, anarakite, Cu2(OlI)3Cl polymorphs, synthesis,Zn-Ni{o substitutions,X-ray data- SoM:rteRs l,a nouvelleespbce mindrale clinoatacamire est un polymorphede Cu2(O[I)3CI,les autres6tant botallackite (monoclinique), atacamite(orthorhombique), et possiblementparatacarrite (rhombo6drique). Ia clinoatacamiteest monoclinique, groupe spatial P21ln,a 6.157Q), b 6.814Q), c 9.LM(5) A, p 99.65(4f, une maille qui est transforrnableen une auhe,pseudorhombo6drique, approximativemeirtcelle de la paratacamite.Nous avons trouvd la clinoatacamitei plusieurs endroits; elle coexiste avec paratacamitedans le sp&imen holotype de cette dernibre.Les deux min6rauxne sont pas facilementdiff6renciables, sauf par m6thodesoptiques et par ditfraction X: la paratacamiteest uniaxe n6gative,tandis que la clinoatacamiteest biaxe n6gative, 2[re756)z.trlraai les plus intensesduilichd de diffraction X de la clinoatacami?e,mdthode des poudres ld ea A\D(hlAl sonc 5.47(100)(T01,011),2.887(n)621,,T03), 2.767(60)8rD, 2.7MQ0)(0r3,202), 2.266(6q2n), 2.243(s0)(0M), et 1,3M(50)824,A4q. I1 est facile de synthetiserla clinoatacamite;nous avons effectu6 une sdrie de slnthbsespour 6tudier ', f incorporation du 7n et 6valuer la formule d'une espbcedont le statut est encore douteux, "l'anarakite de stoechiom6trie * GeologicalSurvey of Canadaconnibution number21695. 62 TIm cANADTANMrNERALocrsr (Culn)2(OFI)3C1.En g6n6ral,les produits de synthbsecontenant plu s de 6Vode 7n @asemolaire) sont hexagonaux,c'est-l-dire une paratacamitrszincifbre, tout commeles echantillons"d'anarakite" provenant de la localit6 type. La paratacamiteholotypique contient de 2 d,3%o(poids) de Zn, etil sembleque I'incorporarionde petites quantit6sd'un autre cation, commeNi ou Zn, soit favorableou essentielled la stabilisationde la strucftre rhombo€driquede la paratacamite.L€ spectrede dii&action X que l'on attribuei la paratacamitedans le fichier de specnasde diffraction, m6thodedes poudres (fiche 25-I4X) est en fait celui de la clinoatacamite. (Traduit par la Rddaction) Mots-cl6s: clinoatacamite,nouvelle eslDce min6rale, pamtacamite,'anarakite', polymorphes de Cu2(OI{)3C1,synthbse, substitutionsZn-Ni-Co. donn6esde diffraction X. ItnonucnoN Pnnnrncal\ffre Cu2(OII)3CI has been consideredto exist as the Paratacamiteis rhombohedral.The unit cell has trimorphous minerals atacamite (orthorhombic), been determinedby single-crystalX-ray methodsby paratacamite(rhombohedral), and botallackite (mono- Frondel(1950), Fleet (1975),and hing et al. (1987). slinis), ths crystal stuctures of which have been Fleet's (1975) crystal-structurestudy showedthat tle described by Wells (1949), Fleet (1975), and mineral has a pronouncedsubcell with a' = el2, c' = c, Hawthome (1985), respectively.In addition to these apparent space-group Rim. T\e superstructure is well-characterizedminernls, a syntheticphase assigned developedby an orderedarangement of the substruc- the sameformula was describedby Oswald& Guenter ture, and resultsin thq spacegroup R3 for the full cell (1971)as paratacamite, and is recordedas paratacamite with a 13.65,c 14.04A. The supersffucturedimensions in the Powder Diffraction File @DF 25-1427): thts were also obtainedby Frondel (1950) and Yrng et al. syntheticphase, however, has a monoclinic cell rather (1e87). than the rhombohedralcell ascribedto paratacamiteby Frondel(1950) and Fleet (1975). ooANAPrlI<TT'p" To the distinct Cu2(OII)3CI polymorphs, two of which are monoclinic. should be added "anarakile" The specimensexamined in this study are from the (Cu,Zn)r(OII)3C1,which was describedby Adib & type locality of 'oanarakite",tb.e Kali Kafi mine, Anarak Ottemann(L972) as a new mineral from the Anarak Province,Iran. The specimenstudied in the most detail Province, han. They recognized the similarity to is from the Pinch collection @inch #508), now part of paratacamite,but obtaineda monoclinic cell different the National Mineral Collection housed at tle from those known for Cu2(OII)3CI.In his abshactof Canadian Museum of Nature, Ottawa, but material the data for anarakite,Fleischer (1973) indicated the similar in appeamncewas obtained from the Royal mingpl to be "probably = zincian paratacamite",and OntarioMuseum, Toronto (M35449), andthe National subsequentlythe status was relegated to that of a Mineral Collection housedat the GeologicalSurvey of discrediiedmineral (e.g.,Nickel & Mandarino 1987). CanadaoOttawa OrMC 14654); all samples have The X-ray powder-diffractionpattern of ooanarakite" aggregatesof small emerald-grcencrystals sprinkled (PDF 25-325) is similar to that for rhombohedral on a distinctively ochreous-colored, thoroughly paratacamite@rondel 1950; PDF 19-389), but there oxidized, limonite-pervadedporous matrix. are slight differencesfrom the data for the monoclinic In their original description of "anarakiteo',Adib synthetic phase as reported by Oswald & Guenter & Ottemam (1972) rcpotod the composition to be (1971;PDF 25-l4n). Otherswho have investigated Cu 48.53, Zn I0,&, Cl 17.25,OH (by difference) paratacamiteand the Cu2(OID3CIpolymorphs (e.9., 23.58 ,ut.%o.On the basis of Cu + Zn = 2. the results Frondel 1950, Sharkey & Lewin 1971, Woods & correspond to (Cut.65ZD035XOII)2.eeClt.e5.Electon- Garels 1986, Pollard et al, 1989) presumablyhave microprobe analysis of grains from tle Pinch attributed these slight variations to the different specimen,mounted in polishedsection, gave a rangeof leeslding techniques that have been used (e.g., compositions:Cu 48.9-53.7, Zn 4.2-8.7, Cl 16.0- Debye-Scherrerand Guinier), or to the substitutional 16.3 vtt.%o.The most 7n-ich compositiotrcorresponds effects of Zn in anarakile. Visual comparison of to (Cut.roZnor0)(Oll)2.e8c11.02,nnd the composition Debye-Scherrer films of (Cu,Zn)2(OH[Cl from poorest in Zn is (Cu1.66Zne.1)(OH)2.eeC11.01. Anarak and synthetic Cu2(OII)3CI prepared in our Debye-Scherrer X-ray pattems of the material are laboratory also showed the patterns to be slightly sharpand were consideredat the initiation of our study different; this study was undertakento resolve the to be in fairly good agreementwith the data given by o'anarakite'n observeddifferences, which intuitively did not seemto Adib & Ottemann(L972) for Clable 1). A be in accord,uriththe effectsof Zn-for-Cu substitution. Guinier - de Wolffpattern taken with Co X-radiation CLINOATACAMITE. A NEW POLYMORPH 63 TABLB 1. X.RAY POWDBR,DATA FOR ANARAKIIts, ZNCI.AN PARATACAMIIE, AND CLINOATACAMIIE Anaraldte Znrian Pararamile Climatac{rfoe (Adlb&Oa€m.m 192) (thir sfidyf (ftis studyf ,t*I L d* il^' l{d ,d d* de hkl td*d* 65 5.476 s.&3 2.N 100 5.4 5.45 101 Lffi 5.A s.ql Ior,otr <5 5.O3 15 4.697 4.&2 W2 N 4.69 4.6E 0G 30 4.68 4.6E 101 5 4.52 4.52 012 <5 4.y 4.53 110 10 3.42s 3.$0 ttr L5 3.424 3.416 110 n 3,M 3.M,3.&7 t2,gm <5 3.019 3.019 104 m 2.fir 2.8W 220 n 2.8% 2.95 g)l & 2.EC7 2.W22.W2 L?L,',O3 1@ 2.755 2.759 gn 75 2.759 2.759 Ll3 @ 2.767 z.nl 11 _ 15 2.139 2.741 M n 2.726 2.7?.6 2V2 7O 2.7A 2.739,2.736 0132s) r0 2.713' 2.714 92,, t0 2.U2 2.W 1r4 LO 2.U3 2.W W 20 2.339' 2.339 82 70 2.253 2.?6 222 6 2.263 2.262 gU @ 2.26t 2.26 nO 50 2.243t 22A q04 l0 2.215 2.215 4n <5 2,210 2.2@ 211 5 2.2AE 2.2W 2-Lr 10 2.M2 2.W N2 10 2.035 2.87 245 5 2.U5t 2.U9 301 10 2.V15 2.Br Lt4 t0 2.927t 2.V27 123 <5 1.9301.931 116 1.940 310 ls t.w r,w2 n4 10 1.901 1.900 lW 5 1.907$1.S 301 10 1.895t 1.894 2_13 m Lw 1.828 6m 25 l.El7 1.817 033 20 1.817* 1.81E 231- 20 1.817