AmericanMineralogist, Volume 67, pages 799-803,1982

Paulingite: variations in composition

Ruov W. TscHenNtcn Zeolite Exploration and Research P.O. Box 5I0I Everett, Washington 98206

nNp WIrueu S. Wtse Department of Geological Sciences University of California Santa Barbara, California 93106

Abstract

Paulingite, originally found at Rock Island Dam near Wenatchee, Washington, is now known from three more localities, (1) near Riggins, Idaho, (2) Chase Creek, north of Falkland,British Columbia,and (3) Three Mile Creek, northwestof Ritter, Oregon.In all four localities paulingite forms early in the zeolite sequencesand is associated with a phillipsite phase. Averaged electron probe microanalysesof the paulingitesgive the following cell contents (l = 16):Rock Island Dam, Washington,Ca1 ssBao rsK+++Naoqs[Alq.szSizzzrOsq]'44HzO; Chase Creek, British Columbia, Ca2.32Mg6l1Srs seBao srK: ssNao.s;[AlrozrSirr z:Osa]' xH2O; Riggins,Idaho, Ca2alMge saSr6 s2Bao.32K+ orNao lz[Alro s6Si31 22Osa]'xH2O; and Rit- ter, Oregon, Ca3.76Ba6.16KzozNao66[,4,1167sSi31.21O84]'34H2O.These compositions can be expressedby the generalformula (K2, Ca, Na2, Ba)5[Al1sSi32Osa]'34-44H2O. The early formation in the crystallization sequenceand the high water content suggest that paulingite forms from relatively dilute pore fluids.

Introduction weighingup to three tons, were dredgedfrom the construction of Rock Is- Paulingite was first described by Kamb and Oke river channel during the paulingite-bearing rock has never (1960)from boulders dredged from the channel of land Dam. The the Columbia River at Rock Island Dam near We- been seenin situ. theseboulders suggests that natchee,Washington, where it is associatedwith Roundingof someof been transported from some clinoptilolite, phillipsite, calcite, and pyrite. It oc- the rock may have although similar zeolite- curs as dodecahedraand has a very large unit cell other locality upstream, found along the river with a : 35.104. bearing rock has not been the dam. Zeolites are not Until recently Rock Island Dam was the only either above or below flows around the dam known locality for paulingite. Three new localities found in the extensive basalt Powerhouseat the have now been found in the Pacific Northwest. The site. Constructionof the Second and information purpose of this paper is to report the locations and dam has now been completed, of the powerhouse site, mineralogy of these occurrences, and to character- regarding the sub-surface half of the river channel, ize the compositional range of paulingite and its which covers the western and geologicmapping' associatedminerals. is availablefrom core drilling Mr. Tracy Lyman, GeotechnicalEngineer of the project, flows of vesicularba- Paulingite localities reports that several salt exist in and below the foundation.These vesi- Rock Island Dam, Washington clesare either empty or have calcite, opal, and iron Material analyzed for this paper was collected oxide fillings or coatings. No zeolites have been from rip-rap bouldersalong the Columbia River on recognizedin thesebasalts. the east sideof the dam. Vesicularbasalt boulders. Paulingite crystals from this locality range from 0003-004x/82/0708-0799$02.00 79 TSCHERNICH AND WISE: PAULINGITE

light yellow to colorlessand commonly are 0.2 to white montmorillonite. A brown weathered zone 0.8 mm in diameter, although a very few reach 3 penetratesthe fragmentsup to 4 cm. mm. The dodecahedronis the common form. but The sourceof the paulingite rock is not readily small cube and trapezohedral modifications are apparent. Volcanic rocks belonging to the Kam- present.The minerals crystallizedin the following loopsGroup are found in the generalarea. Outcrops order: offretite overgrown by erionite (Wise and along the east side of the creek are massive,non- Tschernich,1976) or erionitealone, paulingite, phil- vesicularbasalts without zeolites, while far to the lipsitecovered with a reddish-goldenclay, followed west Mt. Martin is formed of steep basaltic cliffs by clinoptilolite, very rarely chabazite,and lastly covered with thick vegetation. Rock similar in pyrite and calcite. appearanceto the zeolitic rock has been found in glacialdeposits in the area,but thesedo not contain Riggins,Idaho zeolites. It is likely that the zeolitic rock was Paulingiteis believedto havebeen collected from glaciallydeposited and reworkedby the stream,and the area near the junction of PapooseCreek and the originalsource was probably somewhatdistant. Squaw Creek, west of Riggins, Idaho. The speci- Erionite is the most abundantzeolite in the rock, mens were collected by A. D. Ptacek during field formingattractive colorless to golden-yellowhexag- work but he is not sure of the exact locality of his onal prisms up to 0.5 mm long and 0.1 mm in samples.The areanear thejunction of Papooseand diameter. Paulingite, ranging from bright orange Squaw Creeks consistsof over 2300feet of basalt and shadesof yellow to colorless,is found as small belongingto the ColumbiaRiver Group. The upper (0.1 mm) dodecahedraon erionite prisms and as flows are massiveand conspicuouslynon-porphy- large (0.8 mm) crystals lining vesicles. It is also ritic, while the lower unit consists of eight flows associatedwith 0.5 mm cream-colored,elongated ranging from 50 to 150 feet thick with vesicular harmotomecrystals and small aggregatesof color- upper portions. The lower flows are characterized lessheulandite. The completesequence of crystalli- by largeplagioclase phenocrysts, and vesiclescon- zationcan be seenin a singlevesicle, where the clay taining zeolites, calcite, and chalcedony or opal lining is followed by erionite, paulingite, harmo- (Ptacek,1965). tome, heulandite,and lastly clay aggregates(Fig. The paulingite-bearingsamples are red vesicular l). basaltwith 5 to25 mm laboradoritephenocrysts and small alteredpyroxene crystals set in glassaltered dark red. Vesiclesranging from 2 to 20 mm are lined with yellow-gray montmorillonite, which is richly coveredwith small,0.2 to 0.5 mm, colorlessto light yellow, transparentdodecahedra of paulingite.Phil- lipsite, forming small white crystals, is the only other zeolite present. The PapooseCreek area has been searchedby severalmineral collectors, yet the paulingite-bear- ing flow remainsto be found. Red vesicularbasalt is abundantin the area, and cavities are lined with smalltransparent crystals of heulandite,chabazite, analcime,and thomsonite.

ChaseCreek, British Columbia Paulingitewas found in rounded vesicularbasalt fragments in Chase Creek near the junction of CharcoalCreek, north of Falkland, British Colum- bia. Specimensof a very fine-grained,black, olivine basalt consist of microphenocrystsof augite and Fig. l Scanningelectron micrograph ofpaulingite from Chase olivine set in a groundmassof plagioclase Creek north of Falkland, British Columbia. The associated microlites minerals are erionite (E) partially coated with clay and and glass.Common vesicles,ranging from 3 to 30 heulandite (H). The crystallization sequence is erionite, mm across, are lined with a characteristicgray- paulingiteand heulandite. TSCHERNICH AND WISE: PAULINGITE 801

Ritter, Oregon Paulingiteoccurs abundantly,lining vesiclesof a brown-grayolivine basalt, belongingto the Colum- bia River Group near Three Mile Creek, northwest of Ritter, Grant County, Oregon. This is the first locality wherepaulingite has been found in situ.The paulingite-bearingbasalt flow averages2 meters in thicknessand can be traced for over one kilometer to where it is truncated by a northwest trending fault toward the north and is buried in a flat field in the south. The basalt consistsprimarily of pheno- crysts of laboradoritewith a groundmassof augite, olivine, and magnetite,and containsnumerous vesi- clesfrom 2 mm to 4 cm in diameter. The vesiclesin some of the rock appearbarren, but close examination shows the cavities to be richly lined with very small, 0.1 to 0.5 mm, light yellow to colorless, transparent dodecahedraof paulingite. Small trapezohedronmodifications are paulingite Ritter, commonly seen on the dominant dodecahedron. Fig. 2. Scanningelectron micrographof from Oregon,showing the dodecahedralcrystal form. The associated Smectitic clay first lined the vesicles and was phillipsite (P) has been deeply etched. The crystallization followed by paulingite.In some vesiclesclay con- sequenceis clay (C), paulingite,and phillipsite. tinued to form during the paulingitecrystallization and partly engulfs the zeolite, but nowhere com- pletely covers it. In some rocks the clay-paulingite Averaged analysesfrom all four localities are crystallizationis followed by other zeolites in the givenin Table 1. The cell contentsof the associated order: heulandite,Ca-phillipsite, and lastly chaba- zeolitesare listed in Table 2. zite (Fig. 2). Because of the small size of the The range of compositions of the paulingite paulingiteand its early formation, it is not obvious framework from each of the four localities is rela- in specimenscontaining large amounts of other tively narrow. Si/Al is 3.28in the Rock Island Dam zeolites. crystals, but consistentlynear 2.90 in those from the three new localities. The exchangeablecation content exhibits a wider range but all are similar Chemical composition with high amounts of K and Ba. In order to make comparisonsof analysesof all Water determinationon micro-samplesof zeo- known paulingites, we analyzed several crystals lites has been a problem. EMX analysesof the from Rock Island Dam as well as those from the framework and the exchangeable cations, ex- new localities. Paulingite and associatedzeolite pressedas oxides, commonly sum only to 80 or phaseswere analyzedwith an electronmicroprobe. 90%.The remainderis due to water, but all zeolites Crystals or groups of crystals were embeddedin dehydrate to some extent in the vacuum of the epoxy, ground to exposethe center of the crystal, microprobe.In most instancesthe "water by differ- and coatedwith approximately2004 of carbon. An ence" is substantiallyless than the water contentin acceleratingvoltage of 15 kV was used for all the zeoliteequilibrated with some standardhumid- elements,and the samplecurrent was 10nA. Com- ity at atmosphericpressure. mon silicate standards were used, and emission The relatively large number of crystals available data were reducedwith a slightly modified version from the Ritter locality make accuratedensity and of the computerprogram EMIADR 7 (Rucklidgeand H2O content determinations possible. A 45 mg Gasparrini,1969). In order to overcomesome diffi- sampleof hand picked crystals, cleanedof clay by cultiesin analyzingzeolites by EMX methods,large ultrasonic scrubbing,was weighed in the powder beam diameters (at least 20 trr,m)were used. To basket of a Berman balance,using toluene as the minimizethe ion migrationeffect, the countingrates immersionliquid. The mean density of this sample for alkalis were projectedto time zero. is 2.085(5)glcmt, and is markedly lower than the E02 TSCHERNICH AND WISE: PAULINGITE

Table l. Averagedelectron probe analyses,cell contents,and Origin physical properties of paulingites Paulingiteis such a rare and unusual zeolite that it Rock Island De Chase CEeek Rtggins Ritter is worth searchingfor various chemical factors that Washlogton Britlsh Columbla Idaho 0regon might account for its formation. In considering the Electron probe analyses paulingite averege of 5 avetage of I0 average of 4 average of 4 compositionsof the solutionsfrom which crystallizes,it is first instructive to compare the SlO2 63,53 6I.99 61.l3 62.65 Alz0: 16.43 18.04 r7,95 18.36 Si/Al ratios and exchangeablecation content of the Fe2o3 0.16 0.18 0.04 0.08 (Table M8o 0.02 0. 14 0.05 0 associatedzeolites 2). The exchangeable CaO 3.46 4.30 4.41 6.94 cationsincorporated into zeolitesto some measure Sr0 0 o.32 0.07 0 Bao 0,90 4.tl I .58 0.50 reflectthe chemistryof thesesolutions. The zeolite Na20 0.97 0.54 0.43 0.89 KzO 6,47 7,19 compositionsin Table 2 show a fairly wide variation 92,34 92.85 92,99 from locality to locality. The Rock Island Dam and

CeIl contentE with 84 oxygens Rigginszeolites are K-rich, while the ChaseCreek sr 32,2r 3r.23 3t.22 3t.2r mineralsare relatively Ba-rich and the Ritter ones Ar 9.42 10.71 10.80 r0,78 !e .ub .07 .02 .03 are Ca-rich. This demonstratesthat these cations Mgo .11 .04 0 alone do not control the formation of the paulingite Ca 1,88 2.32 2.41 3.70 Sr0 .09 .o2 0 framework. Ba .18 .81 .32 .I0 The Si/Al content of the framework of these Na .95 .42 .85 k 4.44 J.)) 4,63 2.27 zeolites varies within a narrow range with the 7, ettor I -3.7 -1.3 -0.7 exception of the phillipsite and chabazite from Refractive lndex and cell edge Ritter. If the Si/Al ratio of a zeolite is largely D 1.473(1)* r.484(1) 1.480(r) 1.484(1) controlled by the pH of the solution from which it a (il 3s.093(2)** 35,049(7) 35.059(4) 35.088(6) forms (Mariner and Surdam, 1970),then this vari- the ce77 eilge ras refjned fton X-tag lbwder data stanttatlizeil with sgnthetic caF2 (a = s.aSg fu. able is also not controlling the nucleationof these I etror = [ ( A7+ Fe ) -tcharge Ca,S r. k, ilq, Na, K] / ( Al+Fe ) particular frameworks. * Kantb and Oke (1960), ** cordon, Swanson, anil Kanb (1965) Becausethe compositionsand crystallizationse- quencesof paulingite-bearingassemblages are simi- lar to those with faujasite(Wise, 1982),there may 2.24 glcm3calculated by Kamb and Oke (1961).In order verify to that the difference is related to the Table 2. Comparisonof the formulas of paulingiteand associated numberof water moleculeswithin the cell, a 20 mg zeolites. All zeolite formulas have been normalized to 84 samplewas step heatedto 600' C, abovewhich the oxygensfor comparative purposes,and have been listed in their samplebecame non-crystalline. order of crystallization.

The Ritter paulingite contains 18.5%HzO. The si Sr Ba Na water loss upon heating is rapid and continuous. ROCK ISI.AND DAM, WASRINGTON More than half the water was driven off by 150' C, erlonLte/offretlte 31.57 10,41 ,63 1.66 and the remainderwas driven off by 450'C. With paullngice 32.21 9.82 1.88 .L8 .95 4.44 this water content the calculateddensity is 2.098 phllltpelte 31.21 10.91 r.96 .09 2.93 3,11 g/c-'. This valueyields 34.80H2O moleculesper 84 clinoptilolLte 33,83 .48 2.OO .88 t. 33 frameworkoxygens, which compareswith the 44.06 CHASE CREEK, observedin the Rock Island Dam paulingite(Gor- BRITISH COLI',}IBIA don et al., 1966).There is little reasonto suspect erloaite 31.50 10.79 r,47 2.O8 .O9 .07 .05 2,r2 that the Rock Island Dam paulingitewater content paullnglte 31.23 10.7r ,Ir 2,32 ,09 .8r .53 3.55 hamotone 31.20 10.82 .09 ,75 .OA ,39 2,27 is in 3.O8 error. Becausemany of the H2O molecules heulaodlte 33.03 8.97 1.32 2.!4 .15 ,11 ,18 l,3I occur as hydration spheres around exchangeable cations,the Rock Island Dam paulingitewould be RIGGINS, IDAHO expectedto have tnor€ H2O, becauseit has more paullnglte 31.22 10.80 .o4 2.41 .02 .32 .42 4.64 phll1lpslte 31.33 10.70 .03 1.75 .04 .59 largecations than that from Ritter (seeTable 1). .75 4,99

With the variations in Table 1 and the water RIITER, OREGON contentsdiscussed above the general composition paulLngite 3I.21 10.78 3,70 .10 .86 2,17 of paulingite can be expressed by the formula phllltpslte 27.09 15.03 5,49 .39 3.14 -- (K2, Ca, Na2,Ba)5[Alr0Si32O84].34-44 HzO. chabazlte 27,70 14,35 6,62 .18 .04 TSCHERNICH AND WISE: PAULINGITE E03 be similaritiesin origin as well. Breck (1974,p. 340) We also thank Robert and Mary Hillsdon for their assistanceat suggests some zeolite frameworks form around the ChaseCreek and Riggins areas, as well as Jack Zektzet fot paulingite. Tracy Lyman provided the partially information on the Riggins hydrated or hydrated alkali and alkaline geology of the Second Powerhouseat Rock Island Dam. Dave earth cations, which act somewhat like a template. Pierce assistedwith the SEM photography. Such zeolites have high water molecule to cation ratios; paulingite and faujasite may be good exam- References ples. It was suggested(Wise, 1982)that relatively dilute solutions (low salinity) are most likely to Breck, D. W. (1974)Zeolite Molecular Sieves'John Wiley and provide such templates for minerals like faujasite. Sons,New York. Gordon et al. (1966)located cations in paulingite Gordon, E. K., Samson,S., and Kamb, W. B. (1966)Crystal paulingite.Science, 154, l0M-1007. in two kinds of positions,(1) in 8-fold coordination structureof the zeolite Kamb, W. B. and Oke, W. C. (1960)Paulingite, a new zeolite,in with water molecules inside large cages and (2) associationwith erionite and filaform pyrite. American Miner- bonded to the framework and presumably also to alogist,45, 79-91. several water molecules. The implication is that Mariner, R. H. and Surdam, R. C. (1970)Alkalinity and forma- paulingite, because of its early appearancein the tion ofzeolitesin salinealkaline lakes. Science, 170,977-979. (1965) geology of the Seven Devils zeolitesequences, crystallizes when pore solutions Ptacek, A. D. Cenozoic Mountains.Idaho. Ph.D. thesis,University of Washington. are most dilute. It is also interesting to note that the Rucklidge,J. andGasparrini, E. L. (1969)prupepn 7, a computer Si/Al ratio of faujasite and associated phillipsite, program for processingelectron microprobe analytical data' commonly between 2.6 and 2.1 (Wise, 1982), is Department of Geology, University of Toronto. lower than the 3.I to 2.9 of paulingiteand associat- Wise, W. S. (19E2)New occurrence of faujastite in southeastern 67, 794-798. ed phillipsite. This appears to reflect the alkaline California. American Mineralogist, Wise,W. S. and Tschernich,R. W. (1976)The chemicalcompo- nature of the faujasite-bearing host rocks, while sitions and origin of the zeolite offretite, erionite, and levyne. paulingite occurs in sub-alkalinerocks, like those of American Mineralogist, 61, E53-863. the Columbia River Group. Acknowledgments We wish to thank Gordon Dempter for finding the Chase Manuscriptreceived, December 23, 1981; Creek locality and for providing us with specimensfor this study. acceptedfor publication, March 22, 1982.