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Home , Calderite, Fluckite, Geigerite, Kutnohorite

American Mineralogist, Volume 81, pages 1270-1276, 1996

Description and of fianelite, MnrV(VrAs)Or'2HrO, t new from Fianel, Val Ferrerao Graubiinden, Switzerland

JoEr, BnuccER ANDPnrnn Bnm,rpscrr

Mineralogisch-PetrographischesInstitut, Bernoullistrasse30, CH-4056 Basel,Switzerland

AssrRAgr Fianelite occurs in and manganeseores at Fianel, a small mine in Val Ferrera, Graubiinden, Switzerland. It is associatedwith , aegirine,and limonite in thin open fractures crosscutting quartz + + + palenzonaite + aegirine + parsettensite + saneroite + pyrobelonite veinlets. Only a small amount of very minute, tabular, (010)-flattenedfianelite crystalshave been collected.Fianelite, with ideal formula MnrV(V,As)O1.2H2O,crystallizes inthe P2,/n spacegroup with a:7.809(2), b: 14.554(4), c : 6.705(4) A and P : 93.27(3)o.The strongestlines in the X-ray powder pattern are dorr.zto:3.039, dno: 5.32,drrr: 2.72L,arrd dr6361: 1.593A. ttre orange-redmineral is transparent; its optical sign is unknown, ard 2V is small. Fianelite shows a strong pleochroism from yellow to red. Microprobe analyses revealed a partial substitution of As for V, leading to the empirical formula Mn, ,r(V, ,rAso.ooSioo,)O j.2I{2O. The crystal struc- ture of fianelite, refined to R : 0.058, consistsof Mn in octahedralchains bound together by pairs of V in tetrahedra. Among the two V positions, only one hosts As. H is present in HrO groups belonging to the octahedra and occupying channels extending through the structure along [001]. No mineral having a chemical formula with the same atomic pro- portions as fianelite shows similar structural features.

fxrnooucrron terized by shallow-water sedimentation during the Me- (Triimpy Systematicexamination of the geologyand sozoic 1980).The Surettanappe consists of three principal (l) pre-Variscan of several small iron and iron-manganesedeposits em- lithostratigraphic units: a base- (2) bedded in the Triassic sedimentsthat occur on top of the ment containing various lithologies, the "Roffnapor- phyr" (late-Variscan granitic Suretta basement nappe in the easternSwiss Alps led to complex), and (3) a Meso- quartzites the discovery of a new manganesevanadate. Its chemical zoic cover. The latter consists ofbasal followed featuresare related to other natural compounds, such as by dolomitic and calcitic marbles attributed mainly to the Triassic. However, recent structural and lithostrati- reppiaite [Mn!+(VOo)r(OH).; Bassoet al. 19921,variscite graphic (Baudin points (AIPO..2HrO; Kniep et al. 1977), fluckite work et al. 1995) to greater com- plexity in the cover of the Suretta nappe: The Mesozoic [CaMn(AsOrOH)r.2HrO; Bari et al. 1980, Catti et al. 19801,and the haidingerite-group , e.g., krautite seriesseems to be more complete, and there is evidence of nappe tectonics within the cover, which was formerly [Mn(AsO.OH).HrO; Fontan et al. 1975,Catti and Fran- consideredto be autochtonous. chini-Angela I 979, Benekeand Lagaly I 98 I I and haidin- The dolomitic marbles (Triassic) contain numerous gerite [Ca(AsOrOH).HrO; Cassienet al. 1966,Calleri and Ferraris 19671. small stratabound iron and iron-manganesedeposits. All poly- The new mineral was named "fianelite" for the type the lithologies, including the deposits, underwent locality, Fianel, a mine in Val Ferrera, Graubiinden, phaseAlpine metamorphism with a climax under green- (Schmid Switzerland. The mineral and the name have been ap- schist-faciesconditions et al. 1990; Schreurs proved by the International Mineralogical Association l 99l). Commission on New Minerals and Mineral Names. Type Our systematic study of the -hostedminer- petro- material is deposited in the collection of the Naturhis- alization around the Suretta nappe led to a new torisches Museum, Abteilung fiir Mineralogie, Basel, graphic description of the manganoan ores and to the Switzerland. discovery of a generalV-As content associatedwith these ores. The Fianel deposit is remarkable because of the variety of its ores, as originally emphasized by Stucky OccunnrxcE AND GENETIc ENwRoNMENT (1960).The lenticularore body (60 m long x 50 m wide The Suretta nappe (Pennine realm of the eastern part x 12 m in maximal height)consists of (l) an iron oxide of the Central Alps) belongsto the easternmostmembers ore (hematite + quartz + strontian barite + fluorapatite), of the paleogeographic"Briangonnais domain," charac- (2) an iron silicate ore (aegirine + quartz + strontian 0003-004x/96l09I 0- I 270$05.00 1270 BRUGGER AND BERLEPSCH: FIANELITE 127|

TaBLE1. Optical and other physical properties of fianelite

2V6 < 10. Optical sign: unknown Pleochroismon (010): strong, yellow to red na = 1.82(21;ny"* : 1.82(21(at25 'C, for 589 nm) Orientationof the indicatrix: angle b€tween npe and a axis : 16(1)"; the optical axes lie near nFb Density(meas.): 3.21(1) g/cms (heavy liquids) Density (cafc.for the tormula Mn,V(VoeAsos)O?2H2Oli 3.217(2) glcmg Color: orange-red : orange Luster: vitreous Transparent,nonf luores@nt :good parallel{001}? and {100}? Hardness [VHN(15)on (010) face]: mean 86.5 kg/mm'z,range 84-89 kg/ mm2 Twinning: not observed; common intergrowths parallel[1001 barite), and (3) a complex iron-manganeseore (quartz + Frcunr l. SEM photo of fianelitecrystals. Notice the strong -0.25 + + hematite + rhodonite + striationparallel to the 4 axis.Field of view is mm. + + kutnohorite + * + fluorapatite t strontian barite + barylite + me- lative origin. The similarity of the geochemistry of the daite. . . .) radiolarite-hosted deposits with that ofFianel suggestsa Stratabound medaite-rich ores (up to 3 volo/omedaite) similar exhalative origin for the latter deposit. The oc- occur inside the iron and manganeseores as lensesmea- currence of ore fragments within Mesozoic breccia near suring up to 20 cm thick and 2 m in lateral extension. Fianel further supports such a syngeneticmodel. Medaite forms small (<200 prm)xenomorphic grains ly- Or"rrclr, AND orHER PHYSTcALPRoPERTIES ing in the main schistosity and giving the rock a typical red color. The optical and other physical properties of fianelite The ores are crosscut by several generationsof centi- are summarized in Table l. The mineral occurs mostly meter-wide veinlets with mineral assemblagesthat de- in polycrystallinecrusts (<100 pm thick, up to 2.5 mm pend on the embedding rock. Within the medaite-rich in diameter). The rare single crystals (up to 0'2 mm) dis- rocks, these veinlets contain quartz, rhodonite, kutno- play a platy habit with a well-developed {010} pinacoid horite, aegirine, parsettensite,and several rare V miner- and are deeply striated parallel to the a axis' The crystals als: palenzonaite, NaCarMn, (VOo), ; saneroite, are sometimes grouped in rosettes, and intergrowths of NarMn,oVSi'O3o (OH)4; and pyrobelonite,PbMn- individuals parallel to the a axis are common; indeed, VO4(OH). These veins are in turn crosscutby thin open some macroscopically homogenous crystals appear to fractures (

0.6

0.55

0.5

3, 0.45 -Q 0.4 vl { o.rs 0.3

v (pfu) FIcurn 3. Plot of the numberof As atomspfu vs. V atoms pfu from microprobeanalyses of fianelite,normalized on the basisoffour cations.

analytical total is obtained. The empirical formula (on Frcunp 2. Morphotogy of fianelite crystals. (a) Ideal drawing the basis of four cations, mean of eight analyseson three of a fianelite crystal measuredon an optical goniometer flongest grains)is Mn,rr(V,.rrAso.*Sioo,)Oj.2H2O. A good nega- : axis 0.2 mm). Dashed lines indicate traces of the cleavageon tive correlation (R : -0.95) betweenAs and V indicates the (010) face. (b and c) Ideal drawings of two tiny fianelite considerablesubstitution of V by As (Fig. 3). Among rhe that were located on the (010) face of the crystal shown three analyzedgrains, two are homogenous ffil [0.57 and 0.51

Crrr'urc.ql, coMposlTroN Tmu 3. X-raypowder diffraction data for fianelite(d in A) The results of the chemical analysesare summarized in Table 2. Eight analyseswere perfbnned on three crys- d*" hkt tals with the use of a JEOL JXA-8600 electron micro- 7.28 40 7.277 020 probe (EMP) operated at 15 kV, l0 nA, and a surface- 6.87 20 6.872 110 scanningarea of 15 with point-focused 6.06 30 6.082 011 1rm2 a beam. The 5.32 80 5.320 120 following standards,X-ray lines, and detectorcrystals were 4.92 30 4.927 021 used for the calibration: spessartine(Mn-rKa, LiF), adam- 4.921 111 (AsId, 4.68 30 4.679 111 ite TAP), VrOs (V/(a, LiF), and albite (SiKa, TAP). 4.12 20 4.119 130 PrOr, NarO, CaO, and MgO were measured and are all 3.928 40 3.928 031 below 0.05 wto/0.Using WDS scans, no additional ele- 3.436 50 3.436 220 3.361 20 3.362 217 ment with atomic number >9 was detected. The HrO 3.259 50 3.262 012 content could not be determined by an analytical method 3.039 100 3.041 022 owing to paucity material. per- 3.039 230 of However, if the weight 2.785 20 2.785 122 cent of HrO calculated from the HrO content deduced 2.721 60 2.722 231 from the crystal-structureanalysis is added, a satisfactory 2.631 20 2.637 132 2.573 50 2.573 212 2.444 50 2.447 320 2.336 40 2.332 250 2.199 20 2.200 161 TABLE2. Chemicaldata for fianelite(eight analyses on three 2.137 10 2.135 331 grains) 2.133 023 1.989 10 1.990 341 Oxide Range 1.gil 5 1.964 062 1.882 <5 1.884 252 V'O, 38.23 33.15-43.89 4.03 1.838 10 1.841 351 Asro, 13.57 7.23-17.05 4.00 1.825 10 1.828 143 sio, 0.12 <0.04-0.25 0.02 1.708 40 1.707 181 MnO 37.49 36.70-39.50 0.93 1.593 60 1.594 163 Total 89.41 86.96-92.91 2.31 1.593 362 HrO*" 9.64 * Intensitiesassigned by visual estimate. Total 99.05 '. Calculatedon the basis of the cell parameterslisted in Table.4. Indices ' HrO calculatedon the basis of 2 HrO pfu, as determinedby the crystal- were chosen using theoreticalintensities calculated by the program LAZY structure analysis. PULVERIX(Yvon et al.19771. BRUGGER AND BERLEPSCH: FIANELITE t273

TABLE4. Structure-analysisdata for fianelite Srnuctunn soLUTroN AND REFTNEMENT prismatic ldeal formula Mn.V(V,As)O, 2HrO The X-ray data were collected from a short Formulafromstructure refinement MnrV(Vo@Asos)O7.2HrO crystal, about 0.035 x 0.060 x 0.065 mm, with the use P2,ln of an Enraf-Nonius CAD4 automatic single-crystal dif- a 7.809(2)A b 14.5s4(4)A fractometer with Kappa geometry.The lattice parameters 6.705(4)A were determined and refined, using 24 reflections within 93.27(3F < inten- 760.8(s)A. the angularrange 12.8o< 20 53'6'. Diffraction z 4 sities were measured inthe,'t-20 scan mode for 5.58' < lnstrumentation ENRAFNONIUS CAD4 20 < 156, using graphite-monochromated CuKa radia- Rad./mon. Cu/graphite : Scan technique o-20 tion (tr 1.54178 A;. Oata reduction included back- Index range 0 3ol Direct methods were successfully applied using the Final P and F* 0.058and 0.046 program SIR92 (Altomare et al. 1994) to locate all Mn, V, and O sites(13, assumingall positionswere fully oc- cupied). Least-squaresrefinement was performed using As per formula unit (pfu)l and the third showsan internal the program CRYSTALS (Watkin et al. 1985), assigning pfu. zonation from 0.23 to 0.57 As Chebychev weighting to the reflections (Carruthers and Watkin 1979). The observed structure factors are listed X-ru,y sINcLE{RysrAL AND PowDER DATA in Table 5.1 Preliminary single-crystal studies, using Weissenberg From the chemical analysis the total occupancyof the and precession methods, determined the unit cell and two Mn sites was fixed. Later, the occupancyof V vs. As space group and helped to select a crystal of sufficient in the two tetrahedral sites was refined separately,keep- quality for the structure determination. ing the sum of V + As : L The scalefactor, coordinates, The X-ray powder diffraction pattern was obtained with and displacement parameters were simultaneously de- a Gandolfi camera (114.6 mm in diameter) using Mn- rived during the last cycle of refinement,which converged : pow- filtered FeKa radiation (tr 1.93728A;. fne X-ray atR:0.081,R*:0.096. der diffraction data for fianelite are listed in Table 3. Rel- The high R-"* (9 scans)value of 0. 162 and the rela- ative intensities ofthe reflectionswere assignedby visual tively poor R/R* values were not satisfactory. It was estimate. assumedthat the empirical correction for absorption (us- The unit-cell parameterswere derived by least-squares ing ry'scans) was incomplete' By reprocessingthe data refinement using two data sets obtained from different using DIFABS (Walker and Stuart 1983) the R-",r" value crystals:(l) CAD4 data and (2) powder diagram. The two dropped to 0.049. Further refinement of the full matrix data sets show significantly different results for only the convergedat R : 0.058,R* : 0.046.Experimental details : 0 cell parameter: B : 93.27(3) for CAD4 data and B 93.13(3f for powder data. Consideringthe largerange of I A copyof Table5 maybe orderedas Document AM-96-626 V vs. As substitution, the agreementbetween the two cell from the-BusinessOffice, Mineralogical Society of America,l0l5 parameter sets is excellent. The cell parametersreported EighteenthStreet NW, Suite601, Washington, DC 20036,U.S.A. in Table 4 are for the single-crystaldata. Pleaseremit $5.00in advancefor the microfiche.

Tmle 6, Fractional atomic coordinates and displacementparameters for fianelite Ur" xla vlb ub uf ue u$ u8 U." Mn1 0.3987(3) 0.3846(1) o.2378(41 0.0118(4) 0.013(1) 0.0109(9) 0.012(1) 0.0005(9) 0.000(1) 0.001qs) 52(9) 0.016(1) -0.001(1) -0.0010) 0.002(1) Mn2 0.6200(3) 0.2475(2) 0.9615(3) 0.0131(4)0.0100) 0.01 -0.0003(9) 0.0099(e) 0.0070) 0.0007(e) 0.0007(9) V1 0.3285(3) 0.4211(1) 0.7458(4) 0.0088(4) 0.010(1) -0.0006(8) 0.012(1) 0.0135(8) 0.0104(9) -0.0008(8) 0.0001(8) v2 o.040q3) 0.3176(1 ) 0.94e7(3) 0.0119(4) -0.012(4) -0.004(4) o1 0.165(1) 0.2e28(6) 0.158(2) 0.014(2) 0.023(s) 0.019(4) 0.012(4) 0.002(4) 0.012(4) -0.002(3) 0.003(4) 0.005(3) 02 0.058(1) 0.2360(6) 0.77s(1) 0.012(2) 0.019(5) 0.010(4) -0.007(4) 0.003(4) 0.024(4) 0.025{s) -0.oos(4) 0.00s(4) o3 0.115(1) 0.4204(71 0.848(2) 0.008(2) -0.008(4) -0.002(4) o4 0.387(1) 0.5286(6) 0.706(2) 0.016(2) 0.025(5) 0.007(4) 0.026(s) 0.000(4) -0.1640) 0.001(2) 0.018(2) 0.02s(5) 0.011(4) 0.024(5) 0.001(4) 0.000(4) 0.006(4) o5 0.3394(6) -0.005(4) o6 0.4s8(1) 0.3674(7) 0.924(1) 0.013(2) 0.025(5) 0.021(4) 0.011(4) 0.011(4) 0.002(4) 07 0.314(1) 0.3597(7) 0.529(1) 0.01e(2) 0.025(5) 0.023(s) 0.015(5) 0.005(4) 0.007(4) 0.003(4) 0.027(6) 0.019(4) 0.M0(6) -0.008(4) -0.014(5) 0.014{4) wl 0.231(2\ 0.5068(7) 0.236(2) 0.02212) -0.014{5) -0.013(5) W2 0.400(1) 0.1507(9) 0.945(2) 0.026(3) 0.016{s) 0.049(6) 0.04q6) 0.006(5) Notei The thermal ellipsoidis given by expl-2r2(U11h2a*"+ Uek2b'2 + lJvl2c"2+ zuaktb*c' + 2u$hla'c' + 2u'2hka'b'll' ' Occupancy of this site is V : 0.62, As : 0.38. t274 BRUGGER AND BERLEPSCH: FIANELITE

TABLE7. Bond valencesand their sums (>) for each atom in Tmu 9. Selected interatomic angles (") in fianelite fianelite o3-v1-o4 109.3(5) 01-v2-o2 110.9(5) Mnl Mn2 V1 V2 w2 o3-v1-06 104.5(5) 01-v2-o3 108.2(s) o3-v1-o7 107.2(5) 01-v2-o5 112.2(51 o1 0.25 0.36 1.29 o.02 1.92 o4-v1-06 112.8(5) o2-v2-o3 106.7(5) 02 o.37 0.33 1.35 0.0s 2.10 o4-v't-o7 11 1.3(5) o2-v2-o5 113.3(5) o3 0.91 1.09 0.11+ 0.14 2.25 o6-v1-o7 111 .3(s) 03-v2-o5 10s.1(4) o4 0.42 1.49 0.10 2.01 Mean 109.4 Mean 109.4 o5 0.37 1.34 't.29 0.19 0.11 2.01 O1-Mn1-O2 s0.0(4) O1-Mn2-O5 s6.7(4) o6 0.34 0.37 2.00 O1-Mn1-06 85.3(4) O1-Mn2-O6 103.5(4) 07 0.40 0.33 1.30 2.03 O1-Mn1-O7 80.2(4) O1-Mn2-O7 81.6(4) W1 o.32 0.32 O1-Mn1-W1 90.3(4) O1-Mn2-W2 87.1(5) w2 0.31 0.31 O2-Mn1-O4 e1.2(3) O2-Mn2-O5 s1.5(4) 2.'to 2.07 4.99 5.07 02-Mn1-06 82.4(41 O2-Mn2-O6 82.3(4) O2-Mn1-O7 87.9(4) O2-Mn2-O7 93.8(4) ,Vofe.'Bond valenceswere calculated using the formula and constants O4-Mn1-Oo 91.9(4) O2-Mn2-W2 84.6(4) of Altermatt and Brown (1985). Hydrogen-bondvalences were estimated O4-Mn1-O7 102.8(4) OS-Mn2-O6 using Figure 87.9(4) 2 of Altermatt and Brown (1985). 04-Mn1-W1 88.9(4) 05-Mn2-O7 83.7(4) 06-Mn1-Wl 104.1(4) 06-Mn2-W2 93.4(4) O7-Mn1-W1 85.8(5) 07-Mn2-W2 94.7(4) Mean 90.1 Mean 90.1 and structure-refinementresults are summarizedin Table 03'-w1-o3' 75.8(41 01'-w2-o2', 61.8(4) 4, and fractional atomic coordinates and displacement o3'-w1-o4 106.8(5) 01'-w2-o2' 52.8{3) o3'-w1-o4 parametersare listed in Table 6. 167.9(s) 01'-w2-o4 95.7(4) o3'-w1-o5 s7.1(4) o1'-w2-o5 110.5(5) The low chemical-analysistotals from the EMP suggest o3'-w1-o5 78.5(4) 01'-w2-w1 84.9(4) that fianelite contains H atoms. A difference-Fouriersyn- o3'-w1-o7 123.6(6) 02'-w2-o2' 11 1.4(5) o3'-w1-o7 108.6(4) o2'-w2-o4 148.6(6) thesis did not reveal any reasonablepeak that could be o3'-w1-w2 64.2(3) o2'-w2-o4 60.1(3) interpreted as an H position. Two O atoms with very low o3'-w1-w2 139.9(5) o2'-w2-o5 138.7(s) empirical bond-valence sums (Table 7) were assignedto o4-w1-o5 11 1.4(5) o2'-w2-o5 61.6(4) o4-w1-o7 67.4(4) o2'-w2-w1 s0.1(4) o4-w1-W2 112.0(4) o2'-w2-w1 101.9(4) TABLE8. Selectedinteratomic distances (A) in fianelite o5-w1-o7 172.8(61 04-w2-o5 67.3(4) o5-w1-w2 78.4(4) o4-w2-wl 64.s(4) v1-o3 1.83(1) 07-w1-w2 9s.4(s) o5-w2-W1 130.s(5) v1-o4 1.6s7(9) v1-06 1.71('tl v1-o7 1.70(1) Mean 1.72 HrO groups, labeled Wl and W2 (Table 6). These two O v2-o1 1.70(1) positions have significantly higher displacement param- v2-o2 1.680(9) v2-o3 1.76(1) eters, as can be seenfrom Table 6. Geometrical consid- v2-o5 1.68(1) erations from the topology of the structure further sup- Mean 1.71 port this interpretation (seebelow). Mn1-O1 2.30(1) Mnl-O2 2.16(1) Mn1-O4 2.11(1) Srnucrunr DEscRrprroN Mn1-06 2.2o(1) Selectedinteratomic distancesand angles listed Mn1-O7 2.13(1 ) are in Mn1-W1 2.21(1) Tables 8 and 9, respectively.The two averageMn-O dis- Mean 2.19 tances, in comparison with the mean octahedral bond Mn2-O1 2.17(11 Mn2-O2 2.20\1) Iength reported in the literature for Mn2+, preclude the Mn2-O5 2.16(1) presenceof Mn in the trivalent oxidation state.The pres- Mn2-O6 2.16(1) ence oftetrahedra Mn2-O7 2.20(1) and the tetrahedral dimensions are in Mn2-W2 2.22(1) agreement with the pentavalent oxidation state for V, Mean 2.19 which holds for the dominant in both tetrahedral site w1-o5 2.78(21', w1-o3, 2.93(1). populations. The empirical bond valencesestimated from w1-o7 2.95(21* the final refined structure (Table 7) also confirm the in- wl-o3' 2.99(2) ferred cation oxidation states.The structure refinement w1-o4 3.02(2)* w1-o1 3.20(1)-' revealed that As substitutesonly for V2. The As content W2-W1 3.20(2) inferred by the structure analysisis 0.38 As pfu. Electron w2-o2' 2.97(21* microprobe results for zoned polycrystalline w2-o4 2.se(1)' a aggregate w2-05 2.e9(2) not submitted to single-crystalstudy suggestthat As can w2-o1' 3.02(21* be dominant (0.57 As pfu) on the V2 site. w2-o2, 3.10(1) w2-o1' 3.16(2) In the structure of fianelite no closest-packedarray of w2-o6 3.19(2)'- O atoms was observed. The polyhedral framework con- . sists ofoctahedra Bond across the cavity (indicatedtor bonds between H"O group and and tetrahedra.The structural arrange- O; see Fig.5). ment can be describedin terms of octahedraforming .- zig- Bond within the same octahedron (indicatedfor bonds between H2O zagchains subparallel to (l0l) and extendingin the group and O). [T0l] direction. The octahedral chains are bound tosether bv BRUGGER AND BERLEPSCH: FIANELITE 1275

I II ill I I

'"'."*3;lll:il:: @mn:1."ffiii:'.!:1,""@l[?*.-"$l:Y;fi Frcunn5. Orthographicprojection ofpolyhedra in thefiane- lite structurealong [001]. Dashed line indicatesunit-cell outline.

[e.g., krautite, Mn(AsOrOH)'HrO; haidingerite, Ca(AsOrOH)'HrOl and the brushitegroup [e.g.,fluckite, CaMn(AsOrOH)r'2H2Olarc characteiued by a sheetto- pology of octahedra.In the minerals of the variscite group (e.g.,variscite, AIPO.'2H2O), the octahedraare isolated.

AcxNowr.nocunnrs

This study was supported by the Swiss National Funds for Scientific Frcunn4. Orthographicprojection ofthe octahedralchains Research(grant no.21-36495.92). The measurementson the CAD4 were on the (101)plane. The unit-celloutline is shown.All neighbor- made at the Iaboratory for Crystallography, Department of Chemistry, ing tetrahedrawere removed from chainIII. Thetetrahedra that University of Basel,and those on the Philips SEM 515 were made at the crossJinkchains I andII areshown, along with the neighboring SEM-Iaboratory, also at the University of Basel. We are grateful to S. tetrahedraofchains I and II within the (101)plane. Graeser, M. Znhnder, R. Guggenheirn, H. H:inny, A. Edenharter, R. Giere' M. Neuburger, D. Mathys, M. Braun, S. Schmidt, and many othen for their help and constructive discussions.We thank T.S' Ercit and J. Grice (Ottawa) for helpful reviews of the manuscript' pairs oftetrahedra (Fig. 4). Each pair oftetrahedra shares three O atoms with one octahedral chain, two O atoms with a second,and one O atom with a third. The poly- RnrpnnNcps cITED hedral framework contains cavities that cross the whole Altermatt, D., and Brown, I.D. (1985) Bond-valenceparameters obtained structure along [001] (Fig. 5). The cavities are elongated from a systematic analysis of the inorganic crystal structue database. along [30] and [30]. The HrO groups are located on Acta Crystallographica,B41, 244-248' G., Giacovazzo, G., Guagliardi, A., Burla' M.C.' the apices of the octahedra that point to these cavities. Altomare, A., Cascarano, Polidori, G., and Camalli, M. (1994) SIR92: A program for automatic W2 forms weak hydrogen bonds with neighboring O at- solution of crystal structues by direct methods. Journal of Applied oms [smallestW-O distance W2-O2:2.97(2) A; Table Crystallo$aphy, 27, 435. 81.Wl forms a strongerhydrogen bond with 05 a|2.78(2) Bari, H., Cesbron, F., Permingeat,F., and Pillard, F. (1980) Ia fluckite' une A; the other O atoms are at distances=2.93(l) A. Anal- ars6niatehydrat6 de et mangandseCaMnHr(AsOn)r'2HrO, esp0cemin6rale. Bulletin de la Soci6t6 frangais de Min6ralogie quality, however, is necessary nouvelle ysis of a crystal of better et de Cristallographie,103, 122-128. to understand fully the role of the HrO groups in the Basso,R. (1987) The crystal structwe of palenzonaite,a new vanadate structure of fianelite. from Val Graveglia (Northern Apennines, Italy)' Neues Jahr- The only natural manganesevanadate describedso far buch fiir Mineralogie Monatshefte, 3, 136-144. G.,Z.efrro, L., and Palenzona'A.(1992) Reppiaite' is reppiaite,Mn3*(VOo)r(OH)o (Basso etal.1992), a min- Basso,R., Lucchetti, Mnr(OH)n(VOn)2,a new mineral from Val Graveglia (Northern Ap- eral structurally related to cornubite. A structural com- ennines,Italy). Zeitschrift fia Kristallographie, 201, 223-234. parison of fianelite and other minerals with similar atom- Baudin, T., Marquer, D., Barfety, J.-C', Kerchkove' C., and Persoz, F. ic proportions among the vanadates, arsenates, and (1995) A new stratigraphical interpretation ofthe Mesozoic cover of phosphates (of which the crystal structures are known) the Tambo and Suretta nappes: Evidence for early thin-skinned tecton- (SwissCentral Alps). Comptes Rendus de I'Acad6mie des Sciences relationship. In particular, the ics did not reveal any close de Paris, S6rieIIa, 321,401-408. chains of octahedra have no equivalent topology among Beneke,K., and Lagaly, G. (1981) Krautite, MnHAsOn HzO: An intra- these minerals. The minerals of the haidingerite group crystalline reactive mineral. American Mineralogist, 66, 432-435. l2'16 BRUGGER AND BERLEPSCH: FIANELITE

Calleri, M., and Ferraris, G. (1967) Struttura detla haidingerite: CaH(AsO.). ural hydrated Mn-silicate. Neues Jahrbuch fiiLr Mineralogie Monat- H.O. Periodico di Mineralogia, 36, 1-23. shefte,4,161-168. Cam:thers, J.R., and Watkin, D.J. (1979) A weighting schemefor least- Mandarino, J.A. (1976) The Gladstone-Dale relationship: Part L Deri- squaresstructure refinement.Acta Crystallogaphica, A35, 699-699. vation of new constants.Canadian Mineralogist, 14, 498-502. Cassien,M., Herpin, P., and Permingeat,F. (1966) Structure cristalline Schmid, S.M., Riick, P., and Schreurs,G. (1990) The significanceof the de la haiding6rite. Bulletin de la Soci6t6 frangais de Min6ralogie et de Schamsnappes for the reconstructionofthe paleotectonicand orogenic Cristallogaphie, 89, 18-22. evolution of the Penninic zone along the NFP-20 East traverse (Gri- Catti, M., and Franchini-Angela,M. (1979) Kraurite, Mn(H.O)(AsO,OH): sons, Eastern Switzerland). M6moires de la Soci6t6 Geologique de Crystal structure, hydrogen bonding and relations with haidingerite and France.156.263-287. . American Mineralogist, 64, 1248 - 125 4. Schreun, G. ( I 99 l) Structural analysisofthe Schamsnappes and adjacent Catti, M., Chiari, G., and Ferraris, G. (1980) Fluckite, CaMn(tIAsO.),. tectonic units in the Penninic zone (Grisons, SE-Switzerland).Ph.D. 2HrO, a structurerelated by pseudo-polltypism to kraulite MnHAsO4. thesis,Mitteilungen aus dem geologischenInstitut der eidgenossischen HrO. Bulletin de la Soci6t6 frangais de Min6ralogie et de Cristallogra- technischenHochschule und der Universitiit Ziirich, Neue Folge, 283, phie,103,129-134. 204 p. Cortesogno,L., Luchetti, G., and Penco,A.M. (1979)I* mineralizzazioni Stucky, K. (1960) Die Eisen- und Manganerzein der Trias des Val Fer- a manganesenei diaspri delle ofroliti liguri: Mineralogia e genesi. Ren- rera. Beitriigezur Geologieder Schweiz,Geotechnische Seie,37 , 67 p. diconti della Societi Italiana di Mineralogia e Petrologia,35, I 5 l- I 97. Trilmpy, R. (1980) Geology of Switzerland, a guide book: Part A. Ar Fontan, F., Orliac, M., and Permingeat,F. (1975) La krautite MnHAsO.. outline ofthe geologyofSwitzerland, 104 p. Schweizerischegeologische HrO, une nouvelle espdcemin6rale. Bulletin de la Soci6t6frangais de Kommission, Wepf, Basel. Min6ralogie et de Cristallographie,98, 78-84. Walker, N., and Stuart, D. (1983) An empirical method for correcting Geiger, T. (1948) Manganerzin den Radiolariten Graubiindens.Beitrfige diffractometer data for absorption effects. Acta Crystallographica, A39, zur Geologie der Schweiz,Geotechnische Serie, 27, 89 p. l 58- l 66. Graeser, S., Schwander, H., and Suhner, B. (1984) Grischunit (Ca- Watkin, D.J., Camrthers, R.J., and Betteridge, P. (1985) CRYSTALS. Mnr[AsOl"), eine neue Mineralart aus den SchweizerAlpen. Schweiz- Chemical CrystallographyLaboratory, Oxford, U.K. erischeMineralogische und PetrographischeMitteilungen, 64, l-10. Yvon, K., Jeitschko, W., and Parth6, E. (1977) LAZY PULVERIX, a Graeser,S., Schwander,H., Bianchi, R., Pilati, T., and Gramaccioli, C.M. computer program, for calculating X-ray and neutron diffraction pow- (1989) Geigerite, the Mn analogueofchudobaite: Its description and der patterns.Journal of Applied Crystallography, I O, 7 3-7 4. crystal structure. American Mineralogist, 74, 67 6-684. Kniep, R., Mootz, D., and Vegas,A. (1977) Variscite. Acta Crystallogra- phica, B33, 263-265. MaNuscrupr RECETvEDOcronsn 10, 1995 Lucchetti, G., Penco,A.M., and Rinaldi, R. (1981) Saneroite,a new nat- Mexuscnrp'r ACCEPTEDMev 13, 1996