American Mineralogist, Volume 78, pages 822-826, 1993

Tschernichite,a new zeolite from Goble, Columbia CountyoOregon Russrr,r-C. Boccs Department of Geology, Eastern Washington University, Cheney,Washington 99004, U.S.A. DoN,q.Lo G. How,tno PhysicsDepartment, Portland State University, P.O. Box 751, Portland,Oregon 97207-0751, U.S.A. Josnpn V. Svrrrrr Department of Geophysical Sciences,University of Chicago, 5734 South Ellis Avenue, Chicago, Illinois 60637, U.S.A. Gnn-q.LoL. Kr-uN 3804 East Walnut Avenue, Orange,California 92669, U.S.A.

AnsrnLcr The new zeolite tschernichite occurs as 0. l-10 mm, colorlessto white, steeptetragonal dipyramids commonly showing the forms {302} and {001} as drusy linings, radiating hemispherical groups, and single and twinned crystals in small vesicles in dense Eocene basalt near Goble, Columbia County, Oregon, where it has formed through the action of local hydrothermal activity. Associatedminerals include copper,calcite, smectite,boggsite, okenite, mordenite, quartz (chalcedony),heulandite, apophyllite, levyne, offretite, erionite, chabazite, aragonite, opal, analcime, and thomsonite (in approximate order of crystalli- zation). The mineral is tetragonal,possible space group P4/mmm, with a: 12.880(2), and c : 25.020(5) A. A relationship with zeolite beta suggeststhat tschernichite may consist of an intergrowth of an enantiomorphic pair in the tetragonal spacegroups P4r22 and P4r22 and a triclinic polymorph with spacegroup PI. The strongestlines of the X-ray powder diffraction pattern are d (L\, I, hkl: 12.52,10,002 ll.63,32,10l 4.22,14,301; 4.03,100,31l;3.569,13,320; 3.156,16,315;3.062,15,226;2.7 30,10,334;2.114,16,602.The Mohs hardnessis 4Yz,and there are a conchoidal fracture and no observablecleavage. The optical propertiesare uniaxial (-), .: 1.484(l), co: 1.483(l). Tschernichiteshows no to a pale yellow fluorescenceunder both long- and short-wavelength ultraviolet radiation. Electron microprobe analysesshow variation in the Si/Al ratio from about 3/l to 3.7/1. Representativeanalyses give empirical formulas ranging from (CaonrNaoorMgoor) (Si,nrAl, ooFe' 0r)0167.96HrO for the crystalswith low Si contentsto (CaorrNao ,,& orMBooo) (Si63rAl, unFeo or)O,u3.98HrO for the highestSi contents.

INrnonucrroN as his extensive studies of the zeolite occurrencesand A few specimensof tschernichite were first found by associationsin the Pacific Northwest. Rudy W. Tschernich at the Goble location in 1972. At The new mineral tschernichite has been approved by that time, they were thought to be possibly apophyllite the Commission on New Minerals and Mineral Names, with an unusualhabit. In 1985they were shown to R.C.B., I.M.A., and type specimenshave been depositedat the and it was realized that they were not apophyllite because National Museum of Natural History, Smithsonian In- of the lack of cleavage. Preliminary X-ray diffraction stitution, Washington, DC. studies indicated that the material was probably a new zeolite, and work was started on its characterization.At Occunnnucn the same time, attempts were made to locate more ma- Tschernichite is found on the top of a small projection terial at the locality, since only six small specimenswere of basalt located above a cliff along Goble Creek, on the available for characterization. Collecting in 1987-1988 south side of the Neer Road, approximately 50 m west eventually turned up considerably more material, as well of the junction with Highway 30,0.2 km north of Goble, as a secondnew zeolite,boggsite (Howard et al., 1990), Columbia County, Oregon (latitude 46'l'13.1"N, longi- which occurs in close association with tschernichite. tude 722"52'39.6"M).Thisarea was mappedby Wilkin- Tschernichite (pronounced Cher-nich-ite) is named after sonet al. (1946)as the late EoceneGoble VolcanicSeries, Rudy W. Tschernich of Snohomish, Washington, in rec- which consists of porphyritic basalt flows, pyroclastics, ognition of his original discovery of the material, as well and minor amounts of sediments. This area is overlain 0003-004x/93l0708-0822$02.00 822 BOGGS ET AL.: TSCHERNICHITE 613 by 300 m of Oligocenesediments and Miocene Columbia ite and boggsite continued to grow, the single hemi- River basalt. Drilling shows the Goble Volcanics to be spheresof boggsitebecoming enlarged and tschernichite the basementrock, extending to over 1520 m below the forming larger divergent crystals extending from the ini- surface(Wilkinson et aI., 1946). tial smooth hemispheresuntil the vesicle was completely The tschernichite-bearingflow is composedof 0.6-2 m tined. The two minerals do not occur on each other. ofbasal flow breccia, covered by a meter ofhighly vesic- Toward the end of crystallization, both tschernichite ular basalt containing large, elongated,flattened gas cav- and boggsite were partly dissolved. Rarely, small dark ities, which decreasein size and number toward the fine- green Fe-rich smectite spherescrystallized on the surface grained nearly nonvesicular center of the flow. The top of both boggsite and tschernichite. Renewed crystalliza- of the flow has been removed by erosion. Tschernichite tion ofboth boggsiteand tschernichite then enclosedthe is found only in a small area,3 m by 2 m wide and I m clay. thick, which representsa transition zone betweenthe fine- Following crystallization of tschernichite and boggsite, grained, densecentral portion ofthe flow and the highly sparsecream-colored spheres of chalcedony formed, fol- vesicular basal portion of the same flow. lowed by heulandite, apophyllite, levyne, chabazite, cal- Zeolites are abundant in the vesicular portions of the cite, aragonite, or opal. In the adjacent rock, which con- basalt flows and flow breccia in the vicinity of Goble tains larger scatteredtschernichite crystals without Creek. A description of the rock-forming minerals and boggsite,a more complex crystallization sequenceoccurs occurrenceand zonation ofthese zeolitescan be found in (in order of formation): native copper, smectite, okenite, Howard et al. 0990). tschernichite, okenite, opal, mordenite, okenite, levyne, The intensity of rock alteration, amount and size of offretite, erionite, heulandite, opal and analcime, okenite, vesicles,and abundance of zeolites decreasetoward the and chabazite,followed by alteration of all the low-silica massive center of the flow. Black to dark green clay is species(okenite, levyne, offretite, chabazite,analcime) to more abundant. Drusy heulandite is scarce,and zeolites chalky white masses. are found only in a few cavities.Larger tschernichitecrys- A secondhydrothermal phase(drusy heulandite),which tals are found near the rims of the joint blocks of basalt. is widespread in the breccia, and highly vesicular basalt The tschernichiteis often coveredwith okenite, analcime, are found in vesiclesnear the rims of some joint blocks levyne, offretite, erionite, opal, and chabazite,which are overgrown on the tschernichite, boggsite,and altered white usually altered to white formless masses.Unaltered radial massesof the first phase. elongatedprisms of heulandite,spheres of mordenite, and A possible control on the occulTenceof the zeolites quartz arc also present. Less commonly, cavities in the with higher Si contents,tschernichite and boggsite,in the rim ofthe joint blocks contain colorlesstransparent anal- denserparts of the flows may be an increasein the pH of cime, levyne,and, rarely, blue thomsonite. the fluids during alteration ofthe volcanic glassand for- In a small localized portion of the denserock, near the mation of the zeolites due to the restriction of fluid flow central portion of the flow, where alteration is at a min- through the denser parts of the flows (W. S. Wise, per- imum, the rock is very fine grained and nearly nonvesicu- sonal communication). A higher pH would tend to pro- lar. Drusy tschernichite is present in nearly every cavity, duce solutions with higher silica contents, leading to the occasionally accompanied by a single boggsite hemi- crystallization of silica-rich zeolites from these solutions. sphere.The very center ofthe flow contains vesicleswith This is consistent with the smaller silica content in the only tiny smooth tschernichite hemispheresscattered on larger tschernichitecrystals, which occur in the outer, less otherwisebare clay, or with a total absenceofany zeolites denseparts ofthe flows. or clay. The sequenceof crystallization at Goble has been de- Pnvsrclr- PRoPERTIES termined from studies of thousands of specimens.The Tschernichite is colorlessto white, transparentto trans- crystallization of boggsiteand tschernichite representan lucent, with a vitreous luster and a white streak.The cen- early hydrothermal phase that predates the more wide- ters of the larger colorless crystals are commonly milky spread zeolitization in the area, which commenced with white becauseof the many small fluid inclusions. Tscher- the crystallization of drusy heulandite. In the tschemich- nichite showsno to a very pale yellow fluorescenceunder ite-bearing rock, thin sheets of native copper or small both long- and short-wavelengthultraviolet radiation. The mounds of calcite occasionally formed on the walls of fluorescenceis slightly brighter under short-wavelength some vesicles,followed by up to seventhin layers of dark ultraviolet radiation. Tschernichite is brittle, with a con- green Fe-rich smectite, alternating with light green Fe- choidal fracture, and does not exhibit any observable and Ca-rich smectite, both of which become black after cleavage.The Mohs hardnessis 4t/2.The measuredden- exposureto air. Tschernichite was the first zeolite to crys- sity is 2.02(1)dcm', determinedby flotation in a meth- tallize, forming tiny, smooth, colorlesshemispheres 0. l- ylene iodide and acetone solution. This is slightly less 0.5 mm in size, widely scattered on the clay lining in than the calculateddensity of 2.12 g/cm3,most probably nearly all the tiny vesicles.Boggsite usually formed a sin- becauseofthe presenceoffluid inclusions. gle, fine-grained,colorless, radial hemisphere,0.5-l.5 mm The compatibility indices(Mandarino, l98l), calculat- in diameter. in onlv a few of the cavities. Both tschemich- ed using the composition of the larger crystals (Analysis 824 BOGGS ET AL.: TSCHERNICHITE

(001) Monprror,ocrcAl cRYSTALLocRAPHY Tschernichite occurs as steep tetragonal dipyramids {302}, normally terminated by a small basal pinacoid {001} (Fig. 1A). Three other minor dipyramids, {104}, { l0l }, and {502}, have beenobserved on a few crystals. Tschernichite is commonly twinned by reflection on {l0l}, {302},and {304} (Fig. lB, lC, and 1D). Multiple twinning involving both twin planes often occurs, result- ing in complex ball-like groups (Fig. lE and lF). This twinning, as well as possible twinning on other (i0l) planes, contributes to the formation of hemispherical tschernichitegroups. Single crystals of tschernichiterange in size from <0. I mm to I cm rarely. Most crystals are <3 mm in length. Aggregatesof tschernichite occur as 0. l-0.5 mm smooth hemisphericalgroups 0.1-0.5 mm in size,drusy linings of crystalsof 0.1-0.5 mm, radiating groups of crystals of 0.2-3 mm showing distinct dipyr- amidal terminations,and larger single crystalsof l-10 mm and twinned aggregates.The c axis of tschernichite is oriented radially from the center of the hemispherical aggregates.

X-n q.v cRYSTALLocRAPHY Powder X-ray diffraction studies of tschernichite were carried out using a Picker diffractometer, CuKa radiation (\ : 1.54178A), and annealedsynthetic fluorite (a : 5.459 A) as an internal standard. The powder X-ray dif- fraction data are shown in Table l. Least-squaresrefine- ment of the powder data yielded a -- 12380(D A and c : 25.020(5)A, basedon a tetragonalcell. Attempts to determine the space group, using several crystals and Weissenbergphotography by R. C. Boggs, were unsuc- Fig. l. Crystal drawingsof tschernichite.(A) Untwinned cessful becauseof the poor quality of the photographs, crystal,(B) twinningon theplane {101}, (C) twinning on {302}, which show diffusenessalong the c axis, as well as im- (D) and twinningon {304}, (E) multipletwinning on { 101}, (F) perfect reflection profiles and overlapping patterns ofdif- multipletwinning on both and {101} {302}. fraction spots from different domains. Attempts (J. V. Smith and Subrata Ghose, personal communication) to determine the spacegroup using four-circle goniometers l) and the measuredand calculateddensities, are 0.0052 were also unsuccessful.The poor quality of the single- and 0.0531,respectively, which indicatesuperior to good crystal data appearsto be due to mosaic structure, stack- compatibility among density, indices of refraction, and ing faults perpendicular to the c axis, and possibly the chemical composition. presenceof domains of differing symmetry (see optical properties section). The morphological data imply that Oprrc,q.r, PRopERTTES the point group is 4/m2/m2/m. Possiblespace groups Tschernichitewas studied optically using a spindle stage basedon the indexing of the X-ray powder data areP422, and a Na-line interference filter (tr : 5893 A) according P422, P4mm, P42m, P42,m, P4m2, andP4/mmm. The to the methodsof Bloss(1981). Tschernichite is uniaxial most probable spacegroup is P4/mmm, if one assumes (-) with <,r: 1.484(l) and e : 1.483(l) and very low that the inferred point group is correct. The structure of birefringence. Almost all crystals of tschernichite show tschernichite,based on work by Smith et al. (1991), is somewhat walry extinction and are not strictly uniaxial. that of the zeolite beta of Treacy and Newsam (1988), Thin sectionscut to be perpendicular to (100) show areas which consists of an intergrowth of an enantiomorphic of parallel extinction, as well as apparent twin lamellae pair having the tetragonal spacegroups P4,22 and P4322, perpendicular to (001), which show inclined extinction. with a : 12.447(5) A and c : 26.56(l) A (polymorph A), Theserelationships indicate that the symmetry of tscher- and a triclinic polymorph (B) with spacegroup Pl, with nichite may be lower than tetragonal, as is also indicated a = b: 12.4A, c: 14.5A; o = p :73., and y ! 90". by the relationship to zeolite beta (Treacy and Newsam, This structure is based on the comparison of the powder 1988:Smirh et al.. 1991). pattern of tschernichite with a calculatedpowder pattern BOGGS ET AL.: TSCHERNICHITE 825

TABLE1. X-ray powderdiffraction data for tschernichite Trer-e2, Chemicalanalytical data for tschernichite

tl t" I'

26.0 25.O2 001 sio, 54.09 59.78-65.11 03 IT 10 12.5 12.51 o02 Al,o3 15.43 14.61-1 5.23 14.44 32 11.6 11.45 101 CaO 8.27 6.58-7.82 6.58 7 624 o-zJ 004 FeOt o.26 0.00-1.04 no. EAE 5.63 104 Mgo 0.51 0.00-0.17 n.o. 2 497 5.00 005 Na.O o.22 0.00-0.91 000 4.74 4.74 213 KrO n.d 0.00-0.24 006 2 4.45 4.48 221 H.of 22.7 12.26-1553 tJ,tc 14 422 4.23 301 Total 101.48 100.00-10000 100.00 1 4.12 4.17 006 Note. Values are in weight percent. 100 4.03 f 4.07 310 'Analysis )4n otl performedat EasternWashington University. 4 3.971 3.967 106 ". Range of compositionsbased on analysesperformed at Universityof 6 3.708 3.681 224 Chicagoand EasternWashington University. 2 J.OJY otJ f Fe,.,as FerO.. 13 3.569 3.572 320 { H,O by differencefor all but Analysis1. 7 3.500 3.500 206 5 3.333 3.327 117 16 J.tco 3.158 315 15 3.062 J.U/C 226 7 2.990 2.991 306 erating at l5 kV and 2-nA sample current and an energy- 1 2.9s0 2.950 332 2.818 2813 208 dispersive detector, and at Eastern Washington Uni- 10 2.730 2731 334 versity, using an ARL-EMX SM electron microprobe 2 2.617 2.616 424 operating at 15 kV and lO-nA sample cunent and an 5 2.527 .I2.52612.527 327 510 Ortec energy-dispersivedetector. The standardsused were 3 2.439 12.454 336 An,o glass (Na,Al,Si,Ca), microcline (K) from Asbestos, 12.417 513 1 2.300 2299 523 Quebec, and manganesehortonolite (Fe,Mg) at the Uni- (K), 2.220 J2.234 524 versity of Chicago, and albite (Na,Al,Si), microcline 12.210 418 anorthite (Ca), hematite (Fe), and fayalite (Mg) at Eastern 2 2.191 [2.193 2,2,10 1) 1q, 436 Washington University. Becauseof possibleion mobility 2.164 2.162 3,3,10 and HrO loss,a beam diameterof 50 pm was used.HrO 16 2.114 [2.1't6 602 was determined by weight loss on heating of a 14-mg 12.116 2,1,11 'C '| 2.079 2.079 603 sample of the larger crystals to 800 in a Pt crucible. 1 2.064 2.063 5'17 The analysesare shown in Table 2. Analysis I is of the 541 1 2.O02 I2.005 429 larger individual crystals,whereas the other analysesare 'I l2.000 1.9035 1.9035 1,0,13 of the smaller drusy crystals.The smaller crystals show a 2 1.8693 1.8695 519 higher silica content than the larger crystals,probably as ,l 1.8167 RR1 1.8142 J (see I 1.8131 529 a result of differing conditions during their formation 1.7802 J1 .7816 641 occurrencesection). 11.7795 give an empirical formula (on the basis 1 1 6845 1.6845 619 These analyses 3 | .ooJ4 1.6636 2,2,14 of 16 framework O atoms)ranging from (Ca"nrNa",orMgoor) 742 ,l [1.5847 (SirnrAlrooFeoor)O,u.96HrO for the larger crystals to 1.5831 1.5846 "l I 5,3,11 (Cao (Siu 3.98HrOfor [1.s808 803 rrNao,,KoorMgooo) rrAl, unFeoor)O,u' 5,1,13 The HrO content is 1 1 5298 J1.5309 the most silica-rich drusy crystals. [1.5287 737 probably low for the smaller, more silica-rich crystalsbe- 1.s236 3JY 1.5227 J ]l1.5232 6,3,10 causeit was not possible to determine the HrO content 1.5164 1.5162 5,3,12 directly. The data do suggest,however, that the silica- 1 4807 1.4811 4,0,15 ,l probably have lower H,O than do 1.4650 1.4655 834 rich crystals a slightly oco the silica-poor crystals, possibly becauseof the presence 1 1 4584 '1111.4587 .4585 747 of fewer HrO moleculescoordinating the smaller number 1.3951 904 1 1.3547 J This gives a simplified formula of 11.3948 761 of cations. (Ca,Na,K,Mg)rrSi6A12O,6'8HrO for the crystalswith the lowestSi contentand (Ca,Na,K,Mg)o for an approximately 50-50 mixture of polymorphs A nrSiu,.A11 6?0,6'4H2O for the crystals with the highest Si content. The Si/Al and B ofzeolite beta. The presenceofthe triclinic poly- ratio of tschernichiteranges from about 3/l to 3.7/l,with morph can account for the twin lamella, with inclined z : I for all of the above formulas. extinction observedin thin-section.

CoNrposrrroNr AcrNowr,BncMENT Analyses were performed at both the University of The authors wish to thank I.M Steeleofthe University ofChicago for Chicago,using a CamecaSX-50 electron microprobe op- assistancewith some ofthe microorobe analvses. 826 BOGGS ET AL.: TSCHERNICHITE

RnrnnpNcns crrED nichite, the mineral analogueof zeolite beta. Joumal of the Chemical Society,Chemical Communications, 363-364. Bloss,F.D. (1981) The spindle stage:Principles and practices,340p. Treacy, M.M., and Newsam, J.M. (1988) Two new three-dimensional Cambridge University Press,New York. twelve-ring zeolite frameworks of which zeolite beta is a disordered Howard, D.G, Tschernich,R.W., Smith, J.V., and Klein, G.L. (1990) intergrowth. Nature, 322, 249-25 l. Boggsite,a new high silica zeolite from Goble, Columbia County, Or- Wilkinson, W.D., Lowry, W.D., and Baldwin, E.M. (1946) Geologvof egon. American Mineralogist, 75, l2O0-1204. the St. Helens Quadrangle,Oregon. Oregon State Department of Ge- Mandarino, J.A. (1981) The Gladstone-Dalerelationship. IV. The com- ology and Mineral Industries Bulletin, 31, 39 p. patibility conceptand its application. Canadian Mineralogist, 19,441- 450. MANUscRrprREcETvED Decer.agrn 4, 1991 Smith, J.V., Pluth, J.J.,Boggs, R.C., and Howard, D.G (1991)Tscher- Meuuscnrpr ACCEPTEDM,c.nclr 24, 1993

ERRATUM

Octahedral excessmixing properties in biotite: A working model with applications to geobarom- etry and geothermometry,by A. E. Patiflo Douce,A. D. Johnston,and J. M. Rice (v. 78, p. I l3- 13l). The calculatedloci of the QFM buffer at7,10, and 13 kbar shown in Figure I of Patiflo Douce et al. (1993) are in error. The correct loci (calculatedwith standard-statethermodynamic properties from Berman, 1988) are shown here in Figure I (numbers on curyes indicate pressure in kilobars). This error in no way affectsany of the derivations or conclusions of Patiflo Douce et al. (1993)regarding mixing propertiesin biotite. In particular,estimation of Fe3"contents in biotite relies on /o, values in the experimental charges,which were estimated from Reaction I (and shown by symbols in Fig. l), and these values are not affected. The only statement that must be modified is that regarding the redox conditions in NaCl-based piston-cylinder cell assemblies,which are now shown to be at or below QFM and not 2 log units above QFM, as assertedin Patiflo Douce et al. (1993).

-t2

-16 800 900 950 1000 T ('C) Fig. l. The/", values in experiments (symbols) estimated from garnet compositions.