The Grystal Chemistry of Epistilbites

American Mineralogist, Volume 59, pages 1055-1061, 1974

The GrystalChemistry of Epistilbites

EnueNuo Glnr Istituto di Mineralogin e Petrologiadell'Uniaersitd, Modena, Italy

lNo RoulNo Rrneror Departmentol the GeophysicalScierces, Uniuersity ol Chicago, Chicago,lllinois 60637

Abshact

The zeolite, epistilbite, occurs primarily as a lolv temperature-alteration product of basic igneous rocks. Chemical analyses, crystallographic data, and densities were obtained for 13 specimens.The chemical composition varies within narrow limits from the approximate composition CaAlrSiuO.".5ItO. Tetrahedral Si varies between 72.5 and 77.2 wt percent. Ca domi- nates the exchangeablecations, and K is always scarce or absent. The cell constants also vary withinnarrowlimits:a-9.089-9.102,b-17.741-17.802,c-10.205-10.242A-,andp= 124.55-124.68'. The measured density varies within 2.22-2.28 g cm-*. The largest correlation (negative) between chemical and crystallographic data occurs between (Ca f Ba) and p. Smaller correlations occur between a and,c (positive) and between Si/(Si + Al) and (Ca * Ba) (negative). The Dre curves of 12 of the samples can be divided into groups of differing complexity. A listing of the occurrencesreported in the literature is given.

Introduction whose crystals are often grouped in cross-shapedor irregular aggregates: their shape, luster and color Epistilbite,described as a new mineral by Rose are reminiscent of rice grains. In sample no. 12 (1826), is a rather commonbut often misidentified (Furuyada, Japan) no crystal faces are recognizable zeolite. Names synonymouswith epistilbite but now the fills completely the in the obsoleteare: monophane(Breithaupt, 1823), para- since mineral cavities host rock. of no. 5 (Castle stilbite (Von Waltershausen,1853), reissite (Yon The true origin sample Eden, England) is unknown (P. G.Embrey, British Fritzsch,1870), andorizite (Grattarola,1879). Its Museum, personal communication). It was collected structurewas describedfirst by Kerr (1964), and by the late Dr. C. O. Trechmann, who lived at Castle confirmedby Merlino (1965), Perrotta(1967 ), and, Eden but collected the samples from a nearby pile Slaughterand Kane ( 1969) . road We now establishthe range of chemical variation of basalt fragments used as material. other localities where epistil- of epistilbiteand the relationshipsbetween chemical We list in Table 2 all to give as compositionand physical properties. bite has been inferred to occur, in order possible and to E. Galli wasresponsible for the samplecollection. complete a list as of occurrences presence in several X-ray diftraction work, density determination,TG emphasizethat the of epistilbite localities doubtful or unacceptable. We and DT analyses;and R. Rinaldi for the electron of these is obtain samples from many other localities microprobeanalyses. tried to (listed in Table 2), but usually we were informed Description of the Samples that the samples were not available in the museums or in nature. The samplesare listedin Table 1. The most com- No sedimentary epistilbite has been reported to mon crystalhabit for our epistilbitesis that of Figures occur in nature. 15 and28 of Tables141, 143in Goldschmidt( 1916) Band B (Tafeln). Other habits were like hose of Experimental Figures 2, 17, 21, 23. A differentcrystal habit is Electron microprobe analysesfor Si, Al, Ca, Ba, that of sample no. 1 (Elba Island, Italy-"orizite") Na, and K were carried out using an Anr instrument 1055 1056 E. GALLI, AND R. RINALDI

Tlsrn 1. List of SamplesHerein Studied, with Their Occurrences

Donor (lf not owned Lty of occurrence paragenesis, and note neference llo. Loca , by Moddna Universlty)

( Univer3lty of Plsa: Fonte del Prete, near San Vitreous translucent prisnatic crystal's(up to 2x1.5x3 m), Mertlno 1972) Plero ln Cmpo(Iso1a usually lntergrown md twinned, recalling the shape of rice Crattarola(1679) No. 53 drEIba, Italy) grains. Note: also called ori'zl-i.e. (1897) Unlversity of Bologna Giebelbach, near Flesch Aggregates of white transparent Yitreous crystals (up to Hintze (va1ais, Switzerland) 1.5x0.5x2 m) . rtabit 15 and 26. ur -+ / r AO"\ University of Turln: Finkenhiibef, near Glatz l{hite transparent crystals ln cavlties of mygdaloidal "- No, 103do f=Klodzkol, Sllesla rock. (ex-Germny, now Poland) Natural History I\adap, Velence hills SmaII vltreous crystals, perfectly transparentr wlth I,rauritz (L908) Mu6em, Budapest (com. Fej6r, Hungary) stllbite, sphalerite and pyrite. Habit 2. British Musew(Natur- Castle Eden, near HartIe- AgEreEates of small(up to 1.5xO.6x2 m) vltreous trans- Hlntze (l-897) aI Hietory): part BM pool(Durhm Co., England) piieni crystals com!tetely rilling the cavlties ln basalE' Habit 17. LgrT,722

Djupivogurl3 km from the Iarge(up to 7x3.5x10 m) colorless translucent crystals' Hrntze ( 1897) l4t. Bulandstindrl, (Beru- lntergr6rn and twinnedr'foming irregular tabular laths. fjorC, Iceland) Habtt 2E. Unlvergity of Turlni o+ +hn f^^l ^f Aggregates of colorless, cfoualy or reddlsh crystals on Hlntze (I897) the :4t. Bulandstindr black olly rock. No,963b (Icetand) Unlversity of Turln; Thelqarlrornl =Tiegarhon], Aggregates of large(up to 8x2x10 m) colorless, c-loudy or Slauq}Iter :'lo.135Er (Icel-and) Lransparent crystals, complexly intergrownr and romlng and Kane(1969) irregular roof-shaped twlns, wlth mordenite on reddish igneous rock. Habit 21. Mineraloglcal, Museun last-s10e ot 9r10ro SrelI vltreous trdsparent crystals in cavitles in basalt' (Unlverelty of Copen- ( rcetand ) hagen)

Mlneraloglcal Museun lslands Larsefup to 4x1.2x6 m) whiLe translucent crystals, Farbe of Copen- lntergrown and twlmed. Habit 23. lUniverslty "o.pt.ixiy naSen)

Natlonal Sclence Museun I1 Yugauara(Kanagawa Pref ., white transparent crystale(up L0 2xo.6x2.5 m), with-^ Korzwt ( 1953) of Toktrrc, Japan Japan) quartz ln c;vttles i-n lgnedui rock. Habit 15 and 28. National Science Museu Furuyada, Mitam Mllky white crystals, with heulandite and punpellyite . of Tokyo, Japan (Ya@nashl Pref,, Japm) aggregate on eltstitutte conpletely ftlung the cavities 1n basalt, National Science Museun I(lmni, I'tatsuzokl Snall vitreous transparent crystals, with^chabazite and of Tokyq, Japan (shlzuoka Pref., Japan) quartz on lgneous rock, Habit 15 and 2U.

of Goldschnldt(1915). nmber of the habitrelbFto the nwber of the flgures 1n Tabtes 14f-143 in Band III(Tafeln operatedat 10 kV, 0.1 pA beamcurrent and approxi- Density was measured using a torsion micro- mately 10 pm spot size in order to avoid damageto balanceand toluene,according to Berman (1939). or disintegration of the sample. These conditions The cell dimensions were derived by a least- were selectedafter testing yarious settingsof the in- squaresrefinement program applied to the diffrac- strument for loss of Na using one zeolite grain tion bata measured on a Philips powder diftrac- mounted for this purpose. Ten readings for each toApf$r. The instrumental settingswere: Ni-filtered samplewere taken with a countingtime of 10 seconds CuKo, radiation(I : 1.54051)for 20 2 1'8";40 o each. An5osynthetic plagioclase glass was used as a kV, 2p mA; angularspeed f 20 pet minute,0.5-0'1- standardfor Si,Al, Ca, andNa; Kokomo sanidinefor 0.5 slits fqt 20 < 20" and 1-0.1-1 for 20 > 2O". -- K and Ba. The data was reduced following the Cubic Pb(NOs)z with a 7.8568A (see6-0151 "Bence-Albee"method (Bence and Albee, 1968; Jcrns card) was usedas internal standard.The cell Albeeand Ray, 1970), andby the computerprogram dimensionswere refinedby (a) approximatelydeter- EvrpennvIl (Rucklidgeand Gasparrini,1969,Dept. mining these cell parametersfrom -20 lines which Geology, University of Toronto) modified by Steele could be unequivocallyindexed and which were near (1973, Dept. of GeophysicalSciences, University of standardlirles; (b) calculating all dmavalues from Chicago). these rpppoximateparameters; (c) indexing of the Water loss was determinedon approximately 10 whole tracing, taking into account the observed mg of material by means of TG analysis using a structure4rnplitudes (Perrotta, 1965, Ph.D. Thesis, thermal analyzermanufactured by B.D.L. (Bureau Universityof Chicago); (d) least-squaresrefinement de Liaison,Paris). Drn analyseswere also executed of cell parametersusing the linesindexed in step (c)' on a B.D.L. instrument;heating rate of 10'C per For every sample, steps, (b), (c) and (d) were minute, 6 uJPt samplevials, at attenuatorsat 200 V repeqtepat least three times, every time more lines and Aw attenuatorsat 20 mV. (up to 4Q) were unequivocallyindexed. CRYSTAL CHEMISTRY OF EPISTILBITES IO57

Tanlr 2. List of OccurrencesReported in the Literature to Yield Epistilbite, But out of Reach for the PresentStudy

No, Locality of occurrence, and note Re fe renc e

I Bay of Fundy, near Blomidon(Nova Scotia-CANADA) Smith(1971 ) 2 Margaretville, near Port ceorge(Annapolis Co,, Nova Scotia-CANADA) Hintze(1897) 3 Lohja(Sw FINLAND) Duhovnik(1949) 4 cierwiese, near Honnef(Rheinprerrssen-GET|ANY). Note: identification uncertain. Hintze(1897) 5 creinfenstein, near Ehrenfriedersdorf and Schwarzcnbcrg(Saxony-cERMANy) Tetzner and Edelmann(1927) 6 Akrotiri(Santorin[:Thera]-cREECE)! Note: also cal1ed Reissitc, Hintze ( 1897 ) 7 SStoros(com. N6gr5d-HUNGARy) ErdSryi(1942) 8 Thyrill, at the beach of Hvalfrord(Borgafiord-fceland). Note: afso called Parastill;ite. Ilintze(1897) P Tgat-prrri(NE ot Bombay-tNDIA) Hintze(1897 ) 1O Poona ( INDIA ) Daoa ( r 914.1

I I S i nr r, Alrmadnagar Dst . (llombay-INDI A) Hey(1932) l2 Palagonia(Srcrlra-ITALY). Note: optical idcntification on1y. St,rriale(1963) r3 Amagi(1zu Pref.-JAPAN) Wada ( 1q04 | l4 Nikko and Ohora(JAPAN). Note: identification unccrtain. Jimbd(1899) 15 Also-V5cza(Transrlvanra-RUMANIA, Hungary at the tirne of Lhe reFerence). Note: idenlification Hrntze(r897) uilccrtaln.

16 flt. Calvary, near NagySg(Transylvanra-RUtrlAN1A, Hungary at the timc of the reference) Hintze(1897 ) l7 Lunddiirrsfjall(SWEDEN). Notei identification rrncertain. tlintze(1897) l8 Dannemarche reservoir, St. Lawrcnce va1ley(Icrsey-UK) Hey and lloIrant (1933) 19 Rathlin and Portrush(N. Ircland-UK) Hintze(1897 ) 20 Sl{ye island(ScotIand-UK) ttintze ( 1897 )

2l Kibinsky and L()vozersky(USSR). Note: identitication uncertain. Fersman( 1922) 22 Mt.Tzkhara-Tzkhgrq(1asns-Caucasia-USSR). Not"r identif:ication Lrncertain. Smrrnov( 1924) 23 Baytis guarry, near Bedford(New York-USA) Pough(1936) 24 Bcrgcn Hill (Neu J;rsey-USA). Note: wrong identlficationi the mineraf is thomsonite according to Confield(19111. 25 Danbury(Connecticut-USA) Pawloski(r965) 26 Lanakai hilIs(Hawaii-USA) Dunham(1933 )

Tagrp 3. Electron Microprobe and TGA Analyses,and Atomic Ratios of Epistilbite

11 si02 6t.g C?A 57.2 59.5 56.9 60.5 5B.o 6r.5 57.4 5B.T 59.7 A12o3 15'5 17-0 iR a ]7.o 18.3 17.7 ].6.9 17.Q 15.8 ]-7.7 16.4 caO 6.8 8.3 B.o 8.7 8.4 Rl 7.2 7.B 7.3 7.8 8.4 8.6 Qi Bao 0.O 0.0 0.3 n.d. 0.0 o.0 0.1 0.O n.d. o.0 o.o 0.o n.d. Na2O 1.3 o.5 u.o o.7 1.1 r.o I.9 lqtq t.o 0.6 o.5 n4 K2O 0.8 0.8 o.2 0.0 o.1 o.3 0,1 0.0 0.0 o.l 0.o o.0 H2o 14.5 tq ? 1q ) $.5 16.0 1tr l LO.I t( ? tq 6 16.0

Total 100.8 99.7 98.5 101.6 roo . 7 99.5 1o2.1 99.7 101.3 too .3 99.5 99.8 roo.5

sr Id. o 17.8 17.9 L7.9 17.5 a /.o IB.T 17.9 18,4 18.0 L7.7 18.1 1F c qO A1 5.5 6.2 6.2 O.I O.O 6.a 6.2 5.6 5.L 6.4 5.0 Ca 2.2 2.8 2.7 2.8 2.8 D7 )6 t)r z-a 2.8 2.8 )'7 Ba 0.o o.o o.o n.d. 0.O 0.o o.o 0,0 n.d. 0,0 o.o o.o

Na O.7 0.3 0.4 0.4 0.6 1.0 l, t_ 4.9 4.9 0.4 o,3 0.3 K o.3 .0.3 0.2 o.1 0.o o.o o,l 0,1 0,o 0.0 o.r o.0 o.o o 4B.o 48.o 48.o 48.o 48.o )ra ^ 48.o 48.o 48.o 48.o 4B.o 4B.o 48.o

Hzo Lt+.5 15.q 15.8 $.6 16.4 1q 7 1q ) ao.t L5.7 16.0

Ra o.T7z o.742 o .7tt4 o.748 o.725 o.73r o.752 o.742 o.768 o.733 0,752 Eb r.7T I.2O 2.9I -1.13 6.60 2.10 r.97 O.2r 7.34 -a.25 q22 un : Si,z(Si+Af). "E = Balance error (see passaglia, 1970). l4go and SrO were also tested and found absent in a1l the 1058 E, GALLI, AND R. RINALDI

Ga+Ba Tesr-e 4. Cell Parametersof Epistilbites

No. a(A) U(A) c(i) v(ir ) I 9.088(i) 17.74r(rl ro.22511) 124.68(1) 1355.6(1) 2 9.089(1) r7,i.52(2) 1o.226(1) rz4.s7U\ 1358.6(2) 3 9.087(1) L7.766(1) 10.22o(1) 124.58(1) 1358.4(2) 4 9.102(1) L7.?70(21 10.241(1) 124,55(1) 1364.3(2)

5 9.096(1) L2.775(1) 10,229O) 124.58(1) 136r.7Q) 6 9,o98(1) 17.?70(1) 10,24o ( 1 ) 124.58(1) 1363.0(2) 7 9.088(r ) 17,756(1) 1o.236(1) 124.60(1) 1359,7Q) 8 9.o94(1) t7,775(L) 10.235(1) rz4.s9(1) 1362,o(1)

9 9.088(2) 17,741(3) 10.238(2) L24.62(2\ 1358.4(3) 10 9.o95(1) L7.778(r) 1o.220(1) r2r.6r(r) r360,o(1) 1I 9.o96(1) L7.761{2) 10,236(1) 124.58(1) 1361.4(2) 9.082(1 ) t7,8oz(z) io.205(1) 124.55(1) 1359.o(2) 13 9.101(1) 17.'766(2) 10.242(1) 124.61(L) 1363,o(2)

is illustratedin Figure 1; the analysesare plottedin terms of molecular percentagesof Ca * Ba, Na, and K. The diagram shows that the cationic composition of epistilbitesvaries very little; Ca always lla l( dominatesthe exchangeablecations and K is very Fro. 1. Molar plot of exchangeable cations in analyzed low in almostall samples.The compositionalrange epistilbites. of SiOz and AlzOs (Fig. 2) is limited to a very restrictedarea between 8.8 and 9.3 Si atomsper 12 Results and Their Variability tetrahedralsites. The tetrahedralSi/Al ratio in epistilbite is close to that of albite. The unit cell con- The ,chemicalanalyses are reported on Table 3 tent can be describedwith fairly good approximation with their balanceerror, 100x (Alb*-Alth*")/Alth*", by 6{Cao5[Al Si:rO8]2.5H2O]. whereAlto.o" : Na K 2Ca(molar), (Passaglia' * + The water content of epistilbite rangesonly from l97A). Mg and Sr werenot detectedin any sample. 14.5 to 16.5 moleculesper unit cell. The composi- The variability of the exchangeablecation content tion of epistilbite is very close to that of stilbite and is near that of someheulandites. The lattice constantsof the 13 samplesare listed in Table 4. A very limited variation occurs in the latticeconstants: 9.082 < a (.9.1O2A, 1'7.741'< b < 17.802A, 10.2051 c I 1'0.242A, and 124'55 < B < 124.68".The experimentalerror was rounded in the table to a minimum value of 0.001A, but was often 0.0005A or less. Measureddensities (2.22-2.58 g/cm") and cal- culateddensities agree well (Table 5). Drn curyesfor samplesno. 1,7 and 11 (Fig.3)

Tesl-e 5. Densities (g cm-") of Epistilbites

a (meas) Q (calc)a No. g (neas) Q (calc) No. Q

I 2.22r E z.zsG) z,zz(t) r atQ 2.25(2) 2,259 9 z.zs3) 2.260 10 2.26(t) z,zso) 2.240 1l z.zs$) (Ca,BalAlSis0z, (lla,l()nAl$s024 2,28(L) 2.268 tz z.z6(z) 2,254. J 2.245 o z.z6(t) 2,248 IJ z.zSG) Frc. 2. Molar plot of 7 z.z:G) 2.238 SL,o,,-( Ca,Ba) (Na,K) of oxygens per "ALSLO*- "ALSLO,. ap(calc) was obtalned on the basis {8 in analyzedepistilbites. ,:-i + ^al I CRYSTAL CHEMISTRY OF EPISTILBITES 1059

show a gradual passage from one to the other of the three groups. Sample no. 1 shows only two endothermic peaks, the first one wider and deeper with its maximum at 150"C, the second one shal- lower with its maximum at 335oC. A very different behavior is shown by sample no. 11. Besides the two large endothermic peaks at 125 and 300oC, there is a flexure at 245" C and a third endothermic peak, less pronounced than the first two, at 340'C. The Dre curve of sample no. 7 shows an inter- aH mediate behavior. The flexure at245'C is no longer present while the peak at 335'C is reduced to a flexure. The two peaks at 125 and 305'C are always present. All samples showed, after 900"C, the be- ginning of an exothermic reaction. The endothermic peaks result from expulsion of zeolitic water. The last exothermic peak can be explained with the be- ginning of recrystallization of the sample. Differential thermal analysis was carried out for all samples except no. 9 for which not enough material was available. All curves obtained are similar OoC 2000 ,1000 0ltrlo 8000 1000"C to one of the three types reported in Figure 3. Sample Frc. 3. Dtl curve of epistilbites (heating rate: 10'C per no. 12 gave a curve similar to that of no. 1; no. 8 minute). to that of no. 7, andnos. 2, 3,4,5,6, 10, and 13 to that of no. 1 1. These differences in the Dre curves, among samplesof very similar chemical com- correlationsusing the Buo 02R stepwisemultiple- (Sandi position and lattice parameters, could be due to regression program and Franchi, Centro some structural peculiarity such as stacking faults ScientificoIBM, Pisa,Italy). The correlationmatrix that cause a partial occlusion in the channels pres- is reported in Table 6. Unexpectedly,the highest ent in the zeolite framework. The presenceof stacking faults in epistilbite has been emphasizedalso by Slaughter and Kane (1969). The different modalities of water expulsion shown '4 by the three samples of Figure 3 are confirmed by 'z {s the corresponding TG analyses.The samplesbelong- ing to type 11 show the most complex stepwise lu dehydration phenomena. Koizumi (1953) found the I I same complexity in the dehydration curve of a I sample of epistilbite from Yugawara (Japan), which Co+Bo is the same locality as for sample 11.

Correlation Between Chemical Cornposition and Unit Cell Parameters A complete correlation analysis was carried out between the following variables: e, b, c, B, V, R, M, B, (M + B) and H2O where Z = unit cell volume, R = Si/(Si + Al), M = Na * K, B : Ca * Ba, and HzO is the number of water molecules per unit cell. In the course of this analysis every t24,50. variable was assumed in turn to be independent; FIc. 4. Plot of B(- Ca * Ba) versusp in the unit cell of the data in Tables 3 and 4 were tested for possible epistilbites. 1060 E. GALLI, AND R. RINALDI

Trerr 6. Correlation Matrix betweenCell and Chemical Parametersin Epistilbites

g 1.OOo .o5o .706 -.133 .881 -.386 -.182 .305 .o63 -.2L8 .447 b 1.ooo -,477 -.638 .32r -,437 -.481 .649 -.oo7 -.541 .544 1.OOo .108 ,647 -. 086 .28L -.155 '25L .45+ -.o22 I -.358 F 1. OOO -.467 .645 .483 -.87L -.234 .JlO v" 1.ooo -.594 -.199 .499 .249 -.28o .513 Rb 1. OOO .t7L -.7o9 -.523 .273 -.278 MC 1.ooo -.744 .679 .992 -.604 Bd 1.O00 -. 016 -.815 .482 (urn1 1. ooo .589 -,375 M/ (M+B) 1.ooo -.6L9 Hro l.OOO aV: unit cel-L volurne. bn : sil (si+Al). cM : Na+K. dB = cr+B".

(negative) correlation occursbetween B and B (Fig. tion of specific gravities of minerals' Am. Mineral. 24, 4). The structural meaning of this is difficult to 434440. (1E23) Vollstiindige charakteristik des interpret. A negativecorrelation of R with a, b, c, Bnurrnurr, A. Mineral-System. 3rd ed. Dresden and l*ipzig, p. 279. or Z was expectedbut doesnot occur. Lower cor- CrNrtero, F. A. (l9ll) Thomsonite of New lersey. School relations, but still of some significance,occur be- Mines Q.32,215-216. tween 4 and c (positive) and betweenR and B DeN.r, E. S. (1914) The System of Mineralogy of Dana. (negative). Descripthte Mineralogy, 6th ed. John Wiley and Sons, New York. Acknowledgments DunovNx, L (1949) Izpremembe sestavagranita in apnenca ob njunem kontactu. On the contact phenomena between Thanks for encour- are due to Professor Glauco Gottardi pegmatite and marble at I-ohja in SW Finland, Trans. this research; the Research aging to the donors of Petroleum Sloaene Acad. Sci. Arts, Sect. Nat. Sci. (Lubliano), 4, American Society for Fund administered by the Chemical 247-295. (Slovene,with English abstract). grant-in-aid J. V. which made 6276 AC2 to Professor Smith, DuNn,lu, K, C. (1933) Crystal cavities in lavas from the the work possible; to Professor J. V. electron microprobe Hawaiian islands.Am. Mineral. 18' 369-385. for kindly manuscript; to C. Sandi and Smith reviewing the Eno6,rvt, I. (1942) A s6torosi andezit-b6nya hidroterm6lis P. Franchi (Centro Scientifico IBM, Pisa) for their kind 6sv6nyi. Die hydrothermalen Mineralien des Andesit- permission multiple regression to use the BMD O2R stepwise bruches bei Siltoros. Frildtani Kiizlijni (Budapest),72, 197- program. For providing with this research us samplesused in 221. thanks are due to P. Gallitelli, of Bologna; also University FersrvrrN, A. E. (1922) Results of the expedition$ to the Bruno Merlino E. and G. Rigault, University of Turin; S. Khibinsky and Lovozersky tundras. Resultats des ex- Kato, National and M. Franzini, University of Pisa; A. peditions aux Monts Chibines et Lujawrurt en Laponie Science Museum, Tokyo; P. G. Embrey, British Museum of russe. Do&I. Akad. Nauk. SSSR, 59-62. [abstract in' Min- Natural History, London; O. V, Petersen, Mineralogical eral. A bs tr. 2, 261-262 (1924) l. Museum of the and D. Janossy, University of Copenhagen; vox Fnrrzsctt, K. (1870) In, Mineral. Notizen (Frankfurt), Natural History Museum, Budapest. 9, 22. lAs cited in E. S. Dexe (1914) The System ot The financial the Nazionale support of Consiglio delle Mineralogy . 6th Ed., John Wiley and Sons, Ricerche, Roma, is also kindly acknowledged. New York.l. (1972) The crystal References Glr.r,r, E., eNo A. G. Loscsr GnrrroNr chemistry of phillipsites. Am. Mineral. 57, 1125-1145. ArsBe, A. L., eNu L. Rey (1970) Correction factors for Gor,oscnrvrror, V. (1916) Atlas der Krystallformen. Band electron probe microanalysis of silicates, oxides, carbo- 3, Tafeln. Winters, Heidelberg. nates, phosphates, and sulphates. AnaI. Chem. 42, l4O8- Gorrerur, G. (1972) Fortschritte auf dem Gebiet der 1414. Kristallographie und Kristallchemie der Zeolithe. F or tschr' BeNcr, A. E., eNo A. L. ArspB (1968) Empirical correction Mineral.49, 13-30. factors for the electron microanalysis of silicates and Gnem,lnole, G. (1879) Contribuzioni mineralogiche. oxides. .f. G eol. 7 6, 382403. Orizite e pseudonatrolite, due nuove specie del sott'ordine Benrteu, H. (1939) A torsion microbalance for determina- delle zeoliti. Atti Soc. ToscanaSci. Nat. Mem.,4,226-232. CRYSTAL CHEMISTRY OF EPISTILBITES 1061

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