9l
The Canadian M ineralo gi st Vol. 37, pp. 91-98 (1999)
HAtNtrEFROM POQOS DE CALDAS,MINAS GERAIS, BRAZIL
DANIEL ATENCIOI, JOS6 M.V. COUTINHO, MABEL N.C. ULBRICH ENO SILVIO R.F. VLACH
Departamento de Mineralogia e Petrologia, Instituto de Geoci€ncias, Universidnde de Sdo Paulo, Caixa Postal 11348,05422-970 Sdo Paulo, SP,Brasil
RAMIZA K. RASTSVETAEVAANDDMITRY YU. PUSHCHAROVSKY
Department of Geology, Moscow State University, Moscow, 119899, Russia
Aesrnecr
Hainite occurs in evolved alkaline rocks (nepheline syenites and tinguaites) of the Pogos de Caldas massif, Minas Gerais, Brazil It forms pale brownish yellow anhedral, elongate or tabular crystals. The crystals display a perfect { 100J cleavage, indistinct and irregular {010} and [001 ] cleavages,and twinning on { 100} that may be eitber simple or lamellar. Its streakis pale yellow. Hainite is generally poikilitic (except inside the vugs), enclosing alkali feldspar, nepheline and other minerals. Optically, themineralisbiaxial(+),withcrI.662(l),B1663(l),11.675(1),2v2@bs.)30to45",2V,(calc)32.4".Dispersionr
Keywords: hainite, silicate, crystal structure, optical properties, chemical composition, Pogos de Caldas, Minas Gerais, Brazil.
Souuernn,
On trouve la harnite dansles roches alcalines 6volu6es,par exemple, sy6nitesn6ph6liniques et tinguailes, du complexe alcalin de Pogos de Caldas, Minas Gerais, Br6sil. Elle se pr6senteen cristaux x6nomorphesjaune brunAtrepdle, allong6s ou tabulaires. Ils font preuve d'un clivage {100} parfait, de clivages {010} et {001} indistincts et irr6guliers, et de macles sur {1001, soit simples ou lamellaires. La rayure est jaune pdle. La harnite est poecilitique, en g6n&a1(sauf of elle se trouve dans des cavit6s), renfermant le feldspath alcalin, la n6ph6line, et auffes min6raux. Il s'agit d'un min6ral biaxe (+), avec s 1 662(l), B 1.663(1), f 1.6'75(l),2% (obs.) 30 d 45", 2V,(calc.) 32.4".La dispersionr < v est crois6e,et intense.Elle est pl6ochroiQue:X incolor_e,I incoloredjaunepAle, etZjaunedor6.Lahainiteesttriclinique,groupespatialPL,a9.584(2),il.ZAlQ),c 5.708(ltA,a 89.85(2),P 101.22(2),"y 101.03(l)', y 382.5043, Z = l.! .a densit6calcul6e est 3 170 g/cm3.Les septraies les plus intensesdu spectre de diffraction (m6thode des poudres) Id en L(l)(hkl)l sont: 3.081(100X300), 2.970(43)(021),2.635(ll)(202), 1.904(10)(421),2.312(9)(302),2.496(8)(301) et3966(7)(201). La formule empirique, d6riv6e des r6sultats d'analyses d la microsonde 6lectronique, concorde bien avec la formule [NazCa[Ti(OH)z(Si2O7)2]] {Ca3(CaozMno tFeorCee 1)}F2. La formule simplifi6e serait Na2Ca5Ti(Si2O7)2(OH)2F2. (Traduit par la R6daction)
Mots-cl4si haihite, silicate, structure cristalline, propri6t6s optiques, composition chimique, Pogos de Caldas, Minas Gerais, B16sil.
I E-mail address: datencio@usobr 92 THE CANADIAN MINERALOGIST
INtnooucrroN sory, vug- and fracture-filling minerals, mostly identi- fied by optical means,has been cited as occurring in the Hainite was originally described by Blumrich Pogos de Caldas massif: eudialyte, catapleiite, (1893); it was discoveredin cavities and groundmassof lamprophyllite, rinkite, neptunite, manganoan pectolite, phonolites and tinguaites from HradiSte (formerly kupletskite, livenite, normandite, rosenbuschite, "Hoher Hain"), near Fridlant (Friedland), northern Bo- narsarsukite, tainiolite, the problematic "mosandrite", hemia, Czech Republic, and was named on the basis of "giannettite", "rinkolite" and "pennaite" (not yet fully incomplete optical and qualitative chemical data. Com- described in the literature), wadeite, aenigmatite, plete chemical analysis and X-ray powder-diffraction astrophyllite, fersmanite, elpidite, gaidonnayite, data were only recently published by Johan & eech hilairite, burbankite, calcite, fluorite, natrolite, analcime, (1989). A second occurrence of hainite has now been pyrite, galena, manganoan ilmenite, strontianite, establishedin the alkaline massif of Pogos de Caldas, ankerite, kutnohorite, ancylite-(Ce), chamosite, Minas Gerais and Sdo Paulo states,Brazil. In terms of berthierine-lM and lorenzenite. Complete mineralogi- chemical composition and X-ray-diffraction data, the cal data are lacking for theseminerals. For background hainite from Pogos de Caldas is very similar to that from information on the geology and mineralogy of the Pogos the Czech Republic. Morphological and optical data for de Caldas area, see Schorscher & Shea (1992) and hainite from Pogosde Caldas also are presented.These Ulbrich & Ulbrich (1992\. data agree very well with those obtained by Guimardes The hainite crystals described here were collected (1948) for "giannettite" from Pogos de Caldas. Appar- from vugs in the subvolcanic phonolite (tinguaite) ently, Guimardes did not have accessto the paper by mined at Bortolan quarry (sample 5), and also from the Blumrich (1893). The original description of "gian- matrix of the tinguaite at Pedreira da Prefeitura ("City nettite" is so poor that the species and name have not Hall Quarry") (sample 6). been considered valid. In addition, as hainite has his- The abundance ofhainite in the rocks ranges from 0 torical priority (Blumrich 1893) over "giannettite" to 5Vo. As the crystals are generally poikilitic, their (Guimardes 1948), the mineral is more properly to be shapesadapt to the available spaces.The dimensions of called hainite. Unfortunately, the name "giannettite" has the crystals reach a maximum of 0.5 mm in the fine- appeared in the literature since then, as in the structure grained rocks and 2.5 mm in the coarse-grainedrocks. description by Rastsvetaevaet al. (1995). Although a Inside the wgs, extremely rare tabular crystals of hainite formal discreditation of "giannettite" is not possible reach up to 2 mm in length and 0.3 mm in width. Hainite because the type specimen of "giannettite" cannot be also occurs intimately associated with manganoan located, the authors are convinced that "giannettite" is pectolite in elongate (up to 3 cm in length and 1 mm in equal to hainite. width) crystals in vugs (Fig. 2). Hainite is late magmatic where it poikilitically en- OccunnsNce closes alkali feldspar, nepheline and other minerals, and clearly postmagmatic in caseswhere it occurs in vugs. Hainite occurs in evolved alkaline rocks, in particu- The wg-filling crystals of hainite are associatedwith lar nepheline syenites and tinguaites, of the Pogos de unidentified minerals. Mineral UPCI (= unidentified Caldas massif (Fig. 1). The following listing of acces- from Pogos de Caldas #1), displaying rectangular con-
MINASGERAIS
Ftc. 1. Location map of Pogos de Caldas, Minas Gerais, Brazil HAINITE FROM POCOS DE CALDAS, BRAZIL 93
Frc.2. AandB.Poikilitichainite,associatedwithnepheline,alkalifeldsparandaegirine in tinguaite from Pedreira da Prefeitura, Poqos de Caldas. A. Plane-polarized light. B The same view under cross-polarized light. Hainite shows a yellow interference-color' In the top center, a twinned crystal can be seen.C. Sections of larger euhedral tabular crystals of hainite near a vug in tinguaite from Pedreira Bortolan, PoEos de Caldas; plane-polarized light. D. Euhedral tabular crystal of hainite (yellow) inside the vug of C, associatedwith natrolite, analcime, and alkali feldspar. E. Elongate crystals ofhainite (yellow) intimately associatedwith manganoanpectolite, inside a vug in tinguaite from Pedreira Bortolan, Pogos de Caldas, with natrolite, alkali feldspar, aegirine, and nepheline F. Detail ofFigure 2E. 94 THE CANADIAN MINERALOGIST HAINITE FROM POEOS DE CALDAS, BRAZIL 95
tours and maximum dimensions of 8 X 0.2 pm, devel- the help of a universal stage.Indices of refraction were ops along fracture surfacesof hainite crystals. Energy- measuredby immersion of grains in liquids calibrated dispersion analyses indicate a Sr, Ce, Ca, La and Na with the Abb6 refractometer. Table I compares the re- silicate-phosphate,with F and Cl. A second unidenti- sults obtained by Guimardes(1948) with those found in fied mineral (UPC2) grew around the same grain of the present work. Note that the data in columns I and 2 hainite. It is anhedral,about l0 x l0 p.m in area, and is of Table 1 are almost identical. The so-called a Ba, Na, Nb, Ti and Ca silicate. In another sample, "giannettite" of Guimardes (1948) is certainly the same hainite is associatedwith manganoanpectolite, a min- mineral described here. The optical properties are eral similar to tuperssuatsiaiteand a third unidentified clearly different from those attributed to hainite in the mineral (UPC3). The latter is a Ti, Na, Mn, Fe, Ca, K standardtexts (Winchell 1964,Troger 1969). and Al silicate with rectangular contours and maximum Figure 3 illustrates the optical orientation and the dimensions of 120 x 15 pm. It is difficult to evaluate three-dimensionalshapes of crystals as deducedfrom a the extent of interference by the matrix hainite in the combination of different sectionsseen under the micro- resulting chemical data. scope. Extinction angles measuredon the universal stage
Hesn ANo Pgvstcel- Pnoppnrres TABLE I OPTICALPROPERTIES FORIIAINITE Hainite occurs as pale brownish yellow anhedral, FROM POCOS DE CALDAS, MINAS GERAIS, BRAZIL elongateor tabular crystals.Its streakis pale yellow. The {010), {012}, {250}, {111}, t320} and {120} forms were identified by Guimardes (1948), who also quoted a perfect { 100} cleavage,indistinct and inegular {010 } d | 663(2) l 662(l) zv,obs(') 30 30 to 45 and cleavages,and twinning on which {001} {100}, I 1 664(2) l 563(l) 2v,ctlc(') or lamellar. Hainite from the rock may be either simple ,1 | 675Q) l 675(l) c AY(") 20 matrix is generally poikilitic. Hainite from vugs, here birefringme 0 012 0 013 described for the first time, is inclusion-free, but may dispwion rct cited r
Sectionr to c
TABLE 2 CHEMICAL COMPOSTfiON OF HAINTTE ELECTRON-MICROPROBEDATA (WAVELENGTII-DISPERSIONMODE) Frc. 3. Opticalorientation for hainite.
sior 3207 3030 3009 29 3144 3037-3214 3170 3133-3203 are imprecise owing to strong dispersion, and only Tio, 8 06 9,23 I92 912 9 83 9 7r-9 99 9 39 9 t8-9 47 ZrOz 658 491 343 345 233 213-265 2t4 222-3tl averagenumbers are given. II0, na na 006 008 na tra Owing to the poor quality and paucity of the crys- Alps 003 OO2 nd nd 004 004-004 005 00,L006 tals, no FerO31 25 na na na na tr& observations could be made about terminal Nbro, 138 t.2l I 0l 076 082 0't8484 I 06 0 97-l 13 faces, twin laws, the indexing of faces and cleavage Ta2Or022 na na na na n.o planes, and about hardnessand density. MnO 2 06 149 0'15 165 0 92 0 82-I 04 0 68 0 54-092 MgO na OO2 nd nd 0 03 0 03-004 0 04 0 03-005 FeO na 064 079 036 075 07+017 0Et 060-099 CsnrrarcnrDera CaO 3205 3236 3421 3298 3603 3594-3609 3477 3390-3510 SrO na 075 044 2,02 o'19 0 69-092 0 60 0 41-088 La2O3060 na 138 094 117 100-l31 120 073-t44 The chemical data obtainedby Guimaries (1948) are Ce"ql0l 164 250 162 | 96 | 61-221 246 2 l3-3 39 consideredinaccurate. He made a spectrographic Pr2O3na na na na 0 18 0 15-020 027 023436 study N4O3 tra tra tra oa 039 034-043 081 068-092 of a few grains and showed the presenceof Si, Ti, Zr, Y,q na 016 094 049 0 ll 006-016 049 043-057 Mn, Fe, Ca, and Na, with traces of Ta and absenceof ThO, na na na n8 0 ll 0 11,012 0 0t 0,04-0l1 N%O746 744 630 6 17 5 48-654 6'74 636-7 rare-earthelements. Since the mineral could not be sepa- KrO tra 003 nd nd nd nd rated, chemical analyses were performed on material }lO na na na aa 243 246 dissolved from two rock F 1209 773 922 l0 38 5 t3 4 53-582 5 19 4 8l-5 48 samples. Cl na 001 nd nd
{(Nar ooCao.o:)>ro: Ca[(TiozzZre17Nbss6Alss1)>,1 01 (OH)2 (Sir e5Ties5O7)21 ) { Ca3(Ca654Ces r:Feo os Mn6 67La6e5 Sre o+Ndo o+Yo o:Pro orMgo or):, r oo) Fz, Calculations using the Gladstone-Dale relationship were performed using the chemical data, the calculated in good agreement with the structural formula (Rast- density and the recorded indices ofrefraction of the vug svetaeva et al. 1995), {Na2Ca[Ti(O,OH)2(Si2O?)2]] crystals (sample 5). From these calculations, the com- {Ca:(CaorMno lFes 1Ce61)}F2. Inthe given formula, the patibility index is 0.037, indicating, according to (O,OH)2 must have a charge of 2- to achieveneutrality. Mandarino (1979), excellent compatibility. Therefore, it is more likely to be (OH)2. The simplifred The atomic arrangementin hainite (Rastsvetaevae/ formula is Na2CasTi(SizOt) z (OH) zFz. al. 1995) corresponds basically to the structure models The compositions shown in columns I to 4, quoted of gtitzenite (Cannillo et al. 1972), rosenbuschite from the literature, are also in agreement with the struc- (Shibayeva & Belov 1962), ink:tte (Rastsvetaevae/ a/. tural formula, except for the higher F content, possibly 1991) and seidozerite (Simonov & Belov 1960). The due to analytical problems or marked chemical differ- main specific feature of all these structures is the (100) ences in the mineral specimensstudied. "walls" of polyhedra linked by the "ribbons" of octahe- dra parallel to [010], and by [Si2O7]groups. Figure 4 is Cnvsrer.locnAprry AND Cnvsrer Srnucrunr a schematic attempt to discrirninate between these struc-
The mineral is triclinic, spacegroup Pl. X-ray pow- der-diffraction data for hainite from Pogos de Caldas TABLE 4 UNTT-CELLPARAMETERSFORI{AINITE (sample 5) were obtained by means of graphite- monochromatized CuKct radiation and a Siemens a(A) ,(A) c(A) c(') pO y(') v(L1 D5000 diffractometer. The results are compared with the calculated pattern and with the observed data for es86(3) 72se(3) s61q4 eo27(4) l0l l4(4) 101.08(4)37ee4 hainite from Czech Republic in Table 3. es84(2) 7267(2) 570E(l) 8985(2)r0l.22(2) r0l 03(l) 382s0 The parameters of the triclinic unit-cell were refined on an Enraf-Nonius CAD-4F djffractometer (mono- I lkadiste, Boh@i4 Czech Republic (Johu & C@h 1989); the 4 ed c qes w@ htqchmged chromatizedMoKa, )r = 0.71073A) (Table 4).T1tea:b:c 2 Pedrein Bortolaq Pogos de Caldaq Mre Gqais, Broil Cor€sponds to #5 in relationfor the unit-cell parametersis 1.3188:1:0.7855. Table 2; dqiv€d ftm single-crystal studi6: Rastwetawa er 4/. (1995) 98 THE CANADIAN MINERALOGIST
r-O-r DRAKE,M.J. & WBnr, D.F. (1972): New rare earth element to ol t6-61 standards for electron microprobe analysis. Chem. Geol. lool (c) too I 10,179-181. l-Cr{ffi lool GUIMARAES,D. (1948): The zirconium ore deposits of the Pogos de Caldas plateau, Brazil, and zirconium geochem- HH tret istry. Instituto de Tecnologia Industrial, Boletim 6. lool (d) F"Eoo I JonlN, Z. & ercH, F. (1989): Nouvelles donn6essurlaharnite, a-#loel lO rl [NazCa+(Ti,Zr,Mn,Fe,Nb,Ta)1.5s8s.56](Si2O7)2Faet ses re- lations cristallochimiques avec la gritzenite, Na2CasTi (SizOr)zF+.C.R. Acad. Sci. Paris 308, Slr. II, 1237-1242. ffit (e) m MANDARtrTo,J.A. (1979): The Gladstone-Dale relationship.III. r Ti ON" ON",c. FJ Some general applications. Can. Mineral. 17,71-76. 4 lul OCa O Ca- nEe Resrsvnreevl, R.K., Bonurzrrr, B.E. & SHLruKovA, Z.V. Lk AMn (1991): Crystal structure of Khibinian ir*Jte. Sov. Phys. Crystallogr. 36, 349-351.
ftc. 4. Schematic view of the arrangement of cations in the _, PusncseRovsKy,D.Yu. & ArnNcro,D. (1995): "walls" (left) and in the "ribbons" (right) of: a) hainite, Crystal structureof giannettite.Crystallogr. Rep. 40, b) gaitzenite, c) rinkite, d) rosenbuschite, and e) seidozerite 574-578. (Rastsvetaevaet al. L995, modified ftom Cannillo et al. r9'72). ScsonscnEn, H.D., Mol.rrErRo,M.M.G., PEREZAcutr-AR, A., GARo.c.,G.M., BoHLAND,F., NEro & SclruLz-DoBRrcK,B. (1992): Contribuiqeo ao conhecimento da giannettita do complexo alcalino de Pogos de Caldas, MG. Boletim IG- USP, Publicagdo Especial ll (lornadas Cientificas) 12, tures primarily on the basis of different types of cation 105-107. ordering. Thus, the "walls" of hainite contain com- pletely ordered Ca- and Na-atoms in two crystallo- & Srn.c.,M.E. (1992): The regional geology of the Pogos de Caldas alkaline complex: mineralogy and graphically independent octahedra (space group Pl.r, geochemistry of selected nepheline syenites and phonolites. whereas in gcitzenite,Na(Ca1 2Nass) CaaTi(SizOz)z J. Geochem.Explor. 45, 25-51. (F,OH,O)4, according to Cannillo et al. (1972),they are randomly distributed in two symmetrically related oc- Snmaveve, R.P. & BeI-ov, N.V. (1962): Crystal structure of tahedra (spacegroup P1). rosenbuschite, (Ca,Na):(Zr,Ti)[Si2O7](O,F)2. Dokl. Acad. In summary, gdtzenite is characterized by one atom Sci. USSR,Earlh Sci. Sect.143,113-116. of Na, and hainite, by two atoms of Na for 18 (O,OH,F), which leads to ordering and, consequently,to the struc- Slr.roNov, V.I. & Berov, N.V (1960): The determination of ture transformation from centrosymmetric space-group the crystal structure of seidozerite. Sov. Phys. Crystallogr. 4, 146-157. Pl (gtitzenite) to acentric Pl (hainite). SounGs, F., Mnrrr, A.J., Du-lrcNn, J. & SanlnI-l,,I.A. (1991): AcKNoWLEDGENGNTS Mobilidade do zircdnio na bauxitizagdo de rochas alcalinas do macigo de Pogos de Caldas, Minas Gerais. Revisla We acknowledge FAPESP (Fundagdo de Amparo d Brasileira de GeociAncias 21(l), 17-22. Pesquisado Estado de 56o Paulo) and CNPq (Conselho Nacional de Desenvolvimento Cientffico) for financial Tnocrn, W.E. (1969): Optische Bestimmung der gesteins- support,and J.A. Mandarino, E.H. Nickel, A.C. Roberts, bildenden Minerale. 2 - Textband. Schweizerbart, Stuttgart, and R.F. Martin for helpful comments. SRFV is in- Germany. debted to I. Steele for kindly providing a set of micro- ULBRIcH,H.H.G.J. & ULBRTcH,M.N.C. (1992): O maciEo probe standards. alcalino de Pogos de Caldas, MG-SP: caracteristicas petrogrdficas e estruturais. Roteiro das Excursdes do 37" RspnnsNcss CongressoBrasileiro de Geologia (Sdo Paulo) 5.
Bluunrcu, J. (1893):Die Phonolithedes Friedliinder Bezirkes WmcHpr-r, A.N. (1964): Elements of Optical Mineralogy.II. in Nordbdhmen.Tschermaks Mineral. PetroRr.Mitt. 13, Description of Minerals (fourth ed.). John Wiley & Sons, 465-495. New York, N.Y.
CnvNrr-ro,E., Mezz, F. & Rossr,G. (1972):Crystal structue Received October 17, 1997, reyiserl manuscript accepted of gdtzenite.Sov. Phys. Crystallogr. 16, 1026-1030. December 15, 1998.