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Home , Antlerite, Campigliaite, Serpierite

American Mineralogist, Volume 67, pages 3E5-393, 1982

Campigliaite, CuaMn(SO4)2(OH)6.4Id2O, a new from Campiglia Marittima, Tuscany, Itaty I. Occurrenceand description

Srrvro MeNcnerrr aNo Cesare Seseru cNR cento di studio'v;':';"0;,y'7,',3:;,r;i,';!Iy::";;ii per la Mineralogia e la Geochimica dei sedimenti

Abstract

Campigliaite, a new and manganesesulfate mineral, occurs as tufts of light blue crystals in the ore bodies of Temperino mine, campiglia Marittima, Tuscany, Italy. It is monoclinic, C2,with a : 21.707,0: 6.09g;c = I.245A,p : tOO.j..ftre tiny crystals, elongated[010] and flattened {100},are always twinned (100)-The calculated densityis3.06gcm-3.Opticallyitisbiaxiat(-)witho: i.589,p= 1.645,y= l.659.The strongest lines in the X-ray powder partern are 10.6g(100)(200),5.34 (60x400), 3.56 (,14X600),2.673(5)(022 and 800). The structure was solved using 689 independentreflections and refined to an R value of 0.124.The dominant structural feature is the arrangementof copper-oxygenpolyhedra into dense sheets, parallel to (100). The sulfate groups are linked Uy a to both sides of sheets. The Mn atom coordinates four water molecules and two oxygen"o*i. atoms of sulfate groups belongingto the sameCu-O-S layer. Subsequentlayers are connectedto each other by hydrogen bonds. The relationship between the structuies of campigliaite and devillite and is discussed.

Introduction geology and ore deposits of the area is given in the In previous a paper (Conticini et al., l9g0) dealing above quoted paper, specially devoted to secondary with the alteration from Campiglia Marit- minerals. The main tunnel of the third level of the tima (Tuscany, Italy) we briefly described a miner- "Miniera del Temperino" which goesfrom ,,pozzo al, a hydrated basic sulfate of copper and manga- Earle" to "Pozzo Gowet" crosses through sulfide nese, which appeared to be different from any ore bodies (, , , , known sulfate. Further study revealed the mineral pyrrhotite, e/c.). Starting from the point where the in question to be a new species. tunnel leaves the marbles and goes into the skarn, The mineral, CuaMn(SO4)2(OH)6.4H2O,is named many copper oxysalts appear in the order: mala- campigliaite for the locality. Both the mineral and chite, , , chalcanthite. This se- the name have been approved by the Commission quence is related to the increasing acidity of solu- on New Minerals and Mineral Names, IMA. A type tions and the increasing concentration of SOa. specimen is deposited in the mineralogicalMuseum Serpierite also is common and widespread in the of Florence University (regional collection #Zl4lI). tunnel. However the most common and widespread On the basis of the ideal formula, cell parameters secondary mineral is which occurs both as and , campigliaite is related to the transparent crystals and as incrustations on other serpierite-devillite series"and,if one extra molecule minerals. It is interesting to note that when two or of H2O is neglected, it can be considered the more copper sulfates are present together, one can manganese analogueof devillite. observe antlerite often grown on brochantite and chalcanthite grown on antlerite Occurrence and paragenesis Campigliaite was found only on the vugs of an geographic The location of Campiglia Marittima ilvaite-rich skarn, collected in a side-tunnel (..gal- is depicted in Figure l. A brief account of the leria del fornello") of the main tunnel. It occurs as 0003-m4)v82t0304-03E5$02. 00 385 386 MENCHETTI AND SABELLI: CAMPIGLIAITE

LiYorno

o si.n"

I Campiglia M.

Grosseto Fig. 2. Scanningelectron photomicrographof tufts of campigliaite.Crystals are about0.2 mm long.

Mns.ee(Cu3.ez, Zno sg)(SO4) r.78(OH)0.+a' 6. 55HzO on Fig. l. Location map of the Campiglia Marittiina mine, the basis of total metal : 5. Tuscany, Italy. A wet chemical analysis, attempted on a small amount of purified material (less than 1 mg) con- tufted aggregatesof tiny lath-like crystals (Fig. 2) of firmed the previous results for Mn, Cu and Zn a pale blue color, associated with gypsum and (atomic absorption spectrometry). Unfortunately us sometimes with small amounts of brochantite and the scarceness of available material did not allow antlerite. Often campigliaite and gypsum are closely to obtain reliable results for the SO4 content. A mixed; however campigliaite appears grown on TGA analysis, performed in order to obtain the HzO gypsum crystals (Fig. 3). The genesisof campig- content. was also unsuccessful. liaite is probably related to the sulfate solutions formed by the oxidation of pyrite and other sulfide minerals. The presence of manganesein campig- liaite is related to ilvaite. According to Rodolico (1931)ilvaite from Campigliahas 9.5% MnO which is a very high content for this mineral. ChemistrY Preliminary qualitative analyses of campigliaite, made with an oRTEcX-ray microanalyzer, revealed the presenceof Cu, Mn,Zn, S and no other element with atomic number greater than 11. Many quantita- tive analyses were carried out by means of an enr snuQ electron microprobe using chalcopyrite, sphalerite and hortonolite as standards.It is impor- tant to note that these analyses were done under unfavorable conditions, since campigliaite crystals are very tiny and decompose under the electron beam. The average values of the three best analy- ses, MnO 9.95, CuO 40.60,ZnO 4.47, SO320.15, Fig. 3 Scanning electron photomicrograph of crystals of HzO 24.83Vo (by difference), correspond to campigliaite grown on gypsum. Crystals are about 0.2 mm long. MENCHETTI AND SABELLI: CAMPIGLIAITE 387

The structural analysis yielded the formula Table 1. X-ray powder pattern of campigliaite Mn2*Cu*1SO4)2(OH)6.4H2O, where Cu : (Cu, Zn). This formula, which is somewhatdifferent from the hkl d (calc) d (obs) I/Io previous one, is supportedby the density calculated '10.678 from the Gladstone-Dale relationship. This ideal 200 10.68 100 formula requires 400 ].JJY 5.34 60 MnO I 0.50, CuO47 . I l, SO3 23 .7 l, -402 4.239 4.26 1 H2O 18.68Vo. -1 12 4.126 4.13 1 600 3.559 3.56 44 Campigliaite is slowly soluble in acetic acid with- out evident effervescence, -602 3.272 3.28 1 suggestingthe absence 004 2.766 2.768 of CO3. o22 2.670_ 800 z-ot.t 5 204 2.568 X-ray crystallography 2.570 -422 2.475 2.478 1 X-ray single crystal study (Weissenbergcamera 404 2.294 2.295 1 10 0 0 2.136 2.137 and single-crystal ditrractometer) 't.781 revealed all crys- 12 0 0 1.780 2 tals tested to be twinned with (100) as the twin -226 1 qo" 1.595 1 plane. Campigliaite is monoclinic with l_:auesym- 026 1.578 1.578 1 14 0 0 metry 2/m. Space groups consistent 4 E' A with the ob_ 040 i.;;i, served systematic extinctions are C2lm, Cm and C2, the latter being the one favored by the structur- al analysis. The X-ray powder diffraction pattern, given in mined by meansof a least-squarescalculation from Table 1, philips was obtained by meansof a diffrac- powder data are: a : 21.707(l),b : 6.098(2),g : tometer, with CoKa radiation, NaF as internal 11.245(r)4,F : 100.3(1)". standard, ll4" 20 per minute. Indexing was per- formed on the basis of lattice parameters deter- Physicalproperties and morphology mined on the single-crystal diffractometer and tak- Crystals of campigliaite are transparent and light ing into account the intensities of reflections blue in color with vitreous luster. The perfect collected for the structural study. In this powder {100} is fully explained by the structure. pattern only three reflections have relative intensi- The measured density, determined by the heavy- ties greater than 5. Moreover all three of these liquid method,reaches 3.0 g cm-3, but unfortunate- reflections belong to the /r00 series. This depends ly this is an uncertain datum; becauseof the small- on the crystal structure and on a strong enhance- ness of crystals, it was very difficult to determine ment of intensities due to a preferred orientation when the mineral was suspended in the liquid. caused by the {100} cleavage.Keeping this in mind Calculated figures for the density are 3.063 g cm-3 there is a similarity evident between the powder (normalized empirical formula with 7 HzO in total) patterns of campigliaite and serpierite and devillite and 3.060g cm-3 (Ghdstone-Dale law on the same (Faraoneet al.,1967). In the serpieriteand devillite formula using the data of Mandarino, 1976).If l0 patterns are many lines which are not present in the H2O are assumed, as directly derived from the campigliaite pattern; however the three stronger analysis, the value of "Gladstone-Dale" density lines (1100series) are closely related. A slight simi- drops to 2.93e cm-3. The densityvalues of serpiei- larity is also found with the pattern quoted by rcros ite and devillite are very close to that of campigliaite for the mineral woodwardite from Carnarvonshire. (Table 2) and thus support the chemical formula of Wales (card no. I7-l3Z). No other similarities can campigliaite derived from the structural analvsis. be found; actually the chemical formula of wood- Under the microscopel the mineral appeais in a wardite, which is a hydrated sulfate of Cu and Al, is pale greenish-blue color and without evident ple- uncertain, while lattice parameters, space group ochroism. It is biaxial negative with refractive indi- and crystal structure are unknown. According to cesc: 1.589,B: 1.645,y:1.659. The mean Nickel (1976) the name "woodwardite" for the calculated from the Gladstone- Welsh material is not correct in that this speciesis Dale realtionship, using the ideal chemical formula, different from the woodwardite from Cornwall which is its type locality. rOptical properties were wholly determined by Dr. N. Ci- The lattice parameters of campigliaite, deter- priani, University of Florence. 388 MENCHETTI AND SABELLI: CAMPIGLIAITE

Table 2. Chemical composition and crystal data of campigliaite, devillite and serpierite

Campigliaite Devillite Serpierite

(SOn (oH) cu4ca(so4 ) (oH) (cu, zn) (Son) (oH) CunMn ) 2 6.4H2O 2 6.3H20 nca 2 6.3H2o

= c2/c a = 21.707A Sp.9r. c2 a = 20.870A Sp.9r. P21/c a 22.'186A sp.gr. = b = 6.098 b = 6.135 D 9.ztv 1 rr'l = = q/on3 ^ - 11 atF D - 3.00 c,/cm3 c = 22.191 D. = 3.11 S/cm-' c 21.853 o 3.07 m- m- = = F = 100.30 Dc = 3'06 I = 102.73" Dc = 3'06 I 113.360 D 3.08 -- .... --3 = v = t40+.tA v = 2711.4A3 v 2781.8e3

'1 2\1 = 37o X-a 1.589 2Y=52o X A a-13o 1.585 2Y = 39o X A a- 24o .583 =.b ( - Y-c 1.645 (-) Y-c 1.649 (-) Y 1.641 ) strong(+) z = b 1.659 rv,

(*) et aI'(1951) Data for deviLlite and serpierite from Faraone et a].(1957), except those with f.o* Palache

the calculated density and the constants given by atoms in the three structures. However, the optical Mandarino (1976),is 1.632.The value of 2V* mea- orientation and the in the optical axes of sured with an universal stage is nearly 52'. The devillite differ from serpierite. From this point of optical plane is perpendicular to (010) with b : Z view campigliaite follows the behavior of devillite. and a - X. The dispersion in the optic axes is r < v The only noticeable diference between devillite weak. These optical data show an analogy with and campigliaite lies in the absence of an evident those quoted for serpierite and devillite (Table 2). pleochroism in the latter. Refractive indices as well as the optic axial angle Campigliaite crystals are elongatedt0101 and flat- are very similar; the optical sign (-) is the sameand tened {100}. It was not possible to measureinterfa- clearly related to the stratiform arrangement of cial angles.

II. Crystal structure

Cesens SeseI-rr CNR Centro di Studio per Ia Mineralogia e la Geochimica dei sedimenti Istituto di Mineralogia dell' Universitd Via La Pira 4, 50121Firenze, ItalY

Experimental and twinning tallografia Strutturale del CNR, Pavia, Italy). A The search for a crystal suitable for X-ray data least-squaresrefinement of 25 high-anglereflections : : collection was laboriDus, because all the crystals yielded for the unit cell a 21.725(8),b 6.118(6), : tested were multiple crystals. After many trials a c : 11.233(7)Aand F 100.40(5)'in good agree- very thin (100)tabular crystal was chosen. Prelimi- ment with the values obtained by the powder meth- nary X-ray Weissenbergphoto$aphs showedthat it od. Difraction intensities were collected with consists of two individuals, almost in the same graphite monochro.matedMoKo radiation, in the - crystallographic orientation. Furthermore these in- tange 20 < 0 < 25", a 20 scantechnique, integra- dividuals are affected by polysynthetic twinning tion width of 1.3''and scan speed of 0.025'lsec. with (100) as the twin plane. The larger individual Intensities were corrected for Lorentz and polariza- was used for intensity data collection on a Philips tion effects. Becauseof the small size of the crystal PW-l100 four-circle diffractometer (Centro di Cris- the absorption correction was not applied; howev- MENCHETTI AND SABELLI: CAMPIGLIAITE

er, a partial compensationwas achieved by averag_ factor proportional to the overlap degree was ap- ing the intensities of equivalent reflectioni. plied. Figure 4 reports the reflection population due to Out of the 2528 measured intensities a total of the whole crystal and referred to reciprocal lattice 1426 independent reflections were obtained by av- levels with : (levels : ft 2n with ft 2n * 1 can be eraging all the equivalent ones and by correcting, as represented by a similar schemewith ft-odd lattice shown above, for the twin. Of these data only 689 points occupied instead of ft-even ones). Onlv the observations were judged to be actually measured reflections from 0 to 8 for ft index and from 0 to9 for according to the criterion Fo ) 5o (Fo). with q / index are represented. Intensity data could be derived from counting statistics, and were included into lorted two categories; the first one containing in the subsequent least-squares refinement. The the clearly well-separatedreflections (with I : l, i, systematic extinctions (hkl, h I k : 2n r l) are 4,7, 10) and the second,about twice as numerous, consistent with the spacegroups C2, Cm and C2lm; grouping more or less overlappedreflections (with / on the basis of structural considerations : the space 0, 3, 5, 6, 8, 9,ll,12,13). Fromthe intensities of group C2 was assignedand found to be satisfactory non-superimposed reflections of the first set the for the refinement. relative volumes of the two members of the twin On the whole, the data set used for the structure were easily computed. The knowledge of the vol_ analysis is recognized to be of inferior quality ume ratio (A/B : 2.2) allowed the composite inten_ because:(1) the crystal used for data collection is sities of the second set to be subdivided into the tiny and hence the number of "unobserved" inten- intensities of A and B components.Some uncertain- sities is large; (2) the twinning affecting this crystal ties occur in determining the intensities of the makes it dfficult to assignthe right intensity to the partially overlapped reflections; for these a scale reflections partially superimposed;(3) in addition, this crystal is a double crystal and the diffractions due to one individual often interfere with those of the other. The structure refinement of campigliaite t"; l"^ could undoubtedly be improved if an untwinned \ I true single crystal, large enoughto yield a high ratio of observed to unobserved reflections. could I be 9 found. a l

8 Crystal structure analysis As shown in Table 2 there is a strong similarity 7 between campigliaite, devillite, and serpierite in I regard to the chemical formula, the optical data and l6 cell dimensions. In addition, the and the strongestlines of the powder pattern of campig- l5 liaite are comparable with those of devillite and serpierite (Faraone et al., 1967). Therefore. the 4 starting point for the structure solution was the hypothesis that a continuous copper-{xygen sheet J characterizes campigliaite as well as devillite and serpierite (Sabelli and Zanazzi, 1968, l97Z). t-, The copper

Table 3. Fractional atomic coordinatesand isotropic thermal tween the two fold axes, and consequently the Parameters(A') copper-oxygen sheet, to which the Soe groups are attached. is on the screw axes' B eq' From this model all the non-hydrogen atomic positions were determined by reiteration of struc- cu(1) 0.2488(5) a.528(2) -o.ooo1(10) 1.39 cu(2) 0.2590(3) 0.780 (2 ) 0.2511(6) 1.63 ture-factor and electron-densitycalculation' During (2) 0.2s54(6) 1.21 cu(3) 0.2s96(3) 0.258 't.36 full-matrix isotropic (R : 0.18) and aniso- cu(4) 0.2497(s) 0. s18(2 ) o.so13(10) several Mn 0.5331(4 ) 0.437 (21 0.2612(7) 2.41 tropic (R : 0.13) cycles of refinement the tempera- those s(1) 0.11s1(6) 0.20s(2 ) 0. 0s56(9 ) 2.59 ture factors for the oxygen atoms' especially s(2) 0.3930(6) 0.701(2) o.48oo(11) 1.20 belonging to Mn and S polyhedra, were observedto o (1) 0.306(1 ) 0.023(8) 0.187(3) 1.85 o(2) 0.291(1) 0.s41(8) 0.157 (3) 1. s9 increase and to decreasearbitrarily. Also the shifts (3) o(3) 0.181(1) 0.257 (7 ) 0.074 3.06 in the atomic positions were often statistically insig- o(4) 0.19s(1) 0.736(7) 0.061(3) 2.40 nificant. Towards the end of the refinement a final o (5) 0.296 (2) 0.2ss(6) 0.459(3) 2.04 o (5) 0.327(1 ) 0.7ss(6) 0.445(3) 2.63 electron-density difference synthesis was comput- o (7) 0.219(1) 0.026(7 ) 0.311(4) 1,82 ed, but attempts to locate the hydrogen atoms from o (8) 0 .218 (2') 0. ss8(6) 0.316(3) 1.79 this map failed. The hydrogen atoms were placed in -0.065 o (9) 0.087(2 ) 0.104(6) (3) 4.86 positions, at about 1/3of the o(10) 0.108(1) 0.033(6) 0.14s(3) 4.34 geometrically expected o(11) 0.083(1) 0.416(6) o. 069(4 ) 3.89 donor-acceptor distances, and were included in o(12) 0.402(2') 0. s18(7) 0.570(3) 8.12 o (13) 0.416(21 0.586(7 ) 0,372(3) 4.s8 structure factor calculations but not refined. They o (14 ) 0.423(1) 0.914(6) 0. s20(3) 1.4s o(1s) 0.500(2) 0.789(6 ) 0.236(3) 2.73 o(16) 0.573(2) 0.118(5) 0-277(31 2.68 o (17) 0.471 (2) 0.1s8(5 ) 0.3s5(3) 4.83 o(18) 0.484(2) 0. 167(6 ) 0.110(3) 5.62

H(1 ) 0.35s 0.030 0.200 4.00 H(2) 0.333 0.557 0.135 4. 00 H(3) 0.',l58 0.630 0.064 4.00 H(4) 0.330 0.341 0.504 4.00 H(5) 0.182 0.028 0.256 4.00

H(5) 0.168 0.579 o.298 4. 00 H(7) 0.470 0.732 o.177 4.00 H(8) 0.472 0.726 0.280 4.00 H(9) 0.576 0.047 0.345 4,00 H(10) 0.576 0.050 0.208 4.00

H(11) 0.453 Q.0'77 0.410 4.00 H(1 2) 0.4s4 0.301 0.352 4.00 H(13) 0.460 n ?1? 0.095 4.00 _Cut Cu2 H(14) 0.452 0.083 0.050 4 .00

For non hyalrogen atoms B eq.'s are the equlvalent values after Hanilton (1959).

coordination polyhedra should have particular posi- tions: it is very likely that they contribute almost entirely to the structure factors of k-even reflec- tions. In order to avoid the contribution of these reflections, which are the strongest ones also, a Patterson synthesis with &-oddreflections only was computed. This map gives information about Mn- Mn. Mn-S and S-S distances. On the basis of Mn and S positions in the structure the most likely spacegroup is C2 rather than C2lm or Cm, because no important vectors due to mirror symmetry are Fig. 5 The structure of campigliaiteprojected down the b axis' evident in the Patterson map. At this point the Mn Solid circles indicate hydrogen atoms and dashedlines hydrogen atom can be located approximately half way be- bonds. MENCHETTI AND SABELLI: CAMPIGLIAITE 39r

Table 5. Selectedinteratomic distances(A) and angles(.)

cu(1)-o(4) 1 0A Mn-o(16) 2.13 cu(1)-cu(2) 3.19 cu(1)-o(2) 1 .93 Mn-o(12,6) 2.20 cu(1)-cu(3) 3.28 cu(1)-o(1,10) z.zz Mn-o('1s) 2.27 Cu(1)-Cu('1,10) 3.06 cu(1)-o(4,12) 2.34 Mn-O(1 0,3) 2.34 Cu(1)-Cu(3,10) 3.17 cu(1)-o(3,10) z.3t Mn-O(1 8) 2.47 cu(1)-cu(2,12) 3.18 cu(1)-o(3) 2 .42 Mn_O(1 7) 2.53 cu(2)-cu(3) 3.19 cu (2)-cu (4) 3.27 cu(2)-cu(3,1) 2,92 cu (2)-o (8) 1 .85 s(1)-o(3) 1.46 Cu(2)-Cu(4,9) 3.18 cu(2)-o(7,1) 1.92 s('1)-o(10) 1.48 cu(3)-cu(4) 3.23 cu(2)-o(2) 1 0A s(1)-o(11) 1.4e Cu(3)-Cu(4,11) 3.14 cu(2)-o(1,1) 2 .01 s(1)-o(9) 1.51 cu(2)-o(6) 2.40 cu(2)-o(4) o(3)-s(1)-o(10) 108 o(1)-H(1) o(3)-s(1)-o(11) 103 o(2)-H(2)...o(9,10) 3.10 o(3)-s(1)-o(9) 117 o(4)-H(3)...o(11) 3.14 cu(3)-o(7) 1.84 o(10)-s(1)-o(11) 116 o(s)-H(4)...o(12) 2.90 cu(3)-o(1) 1.99 o(10)-s(1)-o(9) 104 o (7)-H (s). . .o (10) 2.76 cu(3)-o(2) 2 .17 o(11)-s(1)-o(e) 109 o(8)-H(5)...O(16,5) 3.12 cu(3)-o(8) 2.21 cu(3)-o(s) 2.29 o (15)-H(7) ...O (9,10) 2.69 cu(3)-o(3) 2 .41 s(2)-o(6) Aq o (1s) -H (8). . .o (13) 2.87 s(2)-o(14) .49 o(9,10)-o(15)-o(13) 76 s (2)-o (121 .50 cu(4)-o(5,9) 1 .85 s(2)-o(13) .55 o (16)-H(9)...o (14,8) 2.59 cu(4)-o(5) 2 .00 o (16) -H (10) . . .o (11 ,4) 2.69 cu(4)-o(8) 2 .08 o(6)-s (21-o(14) 'l 04 o(14,8)-o(16)-o(11,4) 123 Cu(4)-o(7,9) 2 .09 o(6)-s (2)-o(12) 11'l cu(4)-o(5) z. J> o(6)-s(2)-o(13) 109 o (17)-H (11'). ..o (14,2) 2.72 Cu(4)-o(6,'11) 2.47 o(14)-s (21-o(12) 117 o (17)-H (12)...o (13) 2.90 o (14) -s (2)-o (13) 1't6 o(14,2)-o(17)-o(13) 104 o (12)-s (2)-o ('13) 100 o(18)-H(13)...o(9,10) 3.08 o (18)-H (14). . .o (11,'12) 2.73 o(9,10)-o (18)-o ('t1,'t2)'t01

The equivalent Positions (referred to Table 2) are designated by the second num- ber in parentheses and (.1)=x,1+y,zi .are: (21=x,-1+y,z; iZ)='t/2+-x,1/2+y,zi (a)= 1/2+x,-1 /2+y,z; (5)=-1/2+x,1/2+y ,2, (6)=.1-x,y,1-zi e,l=l-xty,-z; ('g)=i-x,-f +y, 1-zi (10)=7/2-x,1/2+y,-ii .(9)=1/2-x,'l/2+y,1-z; (1)=1 /2-x,-iJz+y,'t-zi (z)=1'72- x,-1/2+y,-2.

9:99-0 angles range from 70o to 1130 between adjacent oxygens,-elo and from 1540 to 1790 between opposite oxygens. O-Mn-O angles raige from to 1200 and from 1510 to 1740 .

The standard deviations are 0.01 to 0.05 A for distances and 1.20 to i.7o for angles were assigned isotropic thermal parameters of Discussionof the structure 4.04'. The last cycle of refinementresulted in a An illustration of the structure of campigliaite is final conventional R index of 0.124 for the 689 given in Figure 5 and selectedbonding dimensions "observed" reflections(R : 0.213for all data).The are reported in Table 5. The results confirm the scattering factors for all atoms were taken from supposed close similarities between campigliaite International Tables for X-ray Crystallography and the two similar minerals devillite and serpierite. (1974,p. 99-101).Position4l and isotropic thermal Indeed, the layers of copper-oxygenpolyhedra are parameters are given in Table 3. Anisotropic ther- packed in an essentially identical way, despite the mal parameters and observed and calculated symmetry differencesin the three monoclinic structure factors are listed space in Tables 3a and, 4 groups. respectively.2 These continuous sheets characterize also the structures of ktenasite, (Cu, Zn)5(SOa)2 2To (OH)6 . 6H2O, and , Cuo(SO4)(OH)6 . H2O receive a copy of Tables 3a and 4, order AM-82-196and AM-82-197respectively from the BusinessOffice, Mineralogical (Mellini and Merlino, 1978,1979).Therefore, from Society of America, 2000Florida Avenue, N. W., Washington, the crystal chemical point of view, campigliaite can D. C. 20009.Please remit $1.00 in advancefor the microfiche. be regarded as a new member of the group of the MENCHETTI AND SABELLI: CAMPIGLIAITE copper sulfate minerals which feature these atomic seemsunlikely when compared with the values for slabs. devillite and serpierite, and also with the values of The low precision of the structure analysismakes 21.2 and20.2l3 calculatedfor posnjakite and ktena- a discussion of the observed bond lengths difficult. site. The environment of the Cu2+ ions shows the usual Unfortunately it is not possible to locate with Jahn-Teller effect. The other polyhedra in the struc- certainty any of the hydrogen atoms with the data at ture are also distorted. The Mn atom is coordinated hand. In addition to the GO distancesreported in by four H2O molecules and two O atoms from the Table 5 which are potential hydrogen bonds, there SOagroups. Bond length and anglevariations within are four more distances, namely O(4rc(10'1) the octahedron are relatively wide, with mean Mn- z.grl, o(7Fo(12,11)3-15A, o(l5Fo(16,r) 2.56L O length of 2.31A, substantially longer than the and O(18)-O(18,7)2.694, which could be hvdrogen value 2.224, expected for Mn2* in octahedral coor- bonds. From geometrical considerationsand espe- dination (Shannon and Prewitt, 1969). Both SOa cially on the basis of the balance of valences(Table groups are linked to the copper-oxygen sheet by a 6), though this balance is not very satisfactory, the corner. The mean S-O distance^(1.49A) is longer bonds of Table 5 were preferred. Only one hydroxyl than the average value (1.473A) of well refined hydrogen, H (1), does not seemto be involved in an structures of hydrated sulfates (Baur, 1964). The trydrogenbond, becauseno distanceless than 3.54 scattering of O-S-O angles is wider than usually from O(1) to any oxygen external to the sheet was encountered. observed. The electrostatic balance was computed The number of independent water molecules in after Brown and Shannon (1973) with data from the structure was assumedto be four, in spite of the their Table I and the hydrogen bond curve of result of the chemical analysis because no peak Donnay and Donnay (1973). attributable to an additional oxygen atom was pre- The main signfficant difference between the sent in the Fourier maps. The ratio of the cell structures of devillite and serpierite on one side and volume to the number of oxygen atoms in the cell is campigliaite on the other side lies in the mode of 20.3A3when four water moleculesare assumedin the sheet stackings. In devillite and serpieriteneighbor- formula unit. This is close to the values for devillite ing sheets,with their SOaappendages, are connect- and serpieritewhich are20.4and20.5A3 respective- ed through Ca polyhedra. In campigliaiteMn shares ly. A volume per oxygen of 19.3A3as derived for two oxygen atoms of two SO+ grouPs attached to 5H2O (and obviously the still lower value for 6HzO) the same sheet; on the opposite side Mn is bonded

Table 6. Electrostatic valence balance

cu(1) cu(2) cu(3) cu(4) Mn S(1) s(2)

o(1) OH o.28 0. 34 0t 44 1.00 2.06 o (2) OH o.57 0.41 0"28 N Q? 2.'t3 o(3) o.19+O.'t7 0. 16 1 .63 2.15 o(4) OH 0.57+O.22 0. 15 0.87 1.81 (s) 0.83 2.06 o OH 0.21 0.60+0.42 't o (6) 0.13 0.17+0.14 .71 2.15 o(7) OH 0.43 0.65 0.33 0.80 z .44 o (8) OH 0.54 0.25 0. 34 0.87 2.00 o(e) 1.38 0.13+0.24+O.131.88 o (10) 0.31 1.50 o.20 2.o1 o (11) 1.49 0.13+0.22+0.20 2.04 o(12) 0.42 1.48 0.17 2.O7 o (13) 1.27 0.18+0.18 1.63 o(14) 1.54 o.26+0.19 I .99 o(1s) Ow 0.35 0.76+0.82 1.93 o (16)o\,, 0.49 0.74+0.78 0.13 2.14

4 a2 o (17)Ow 0.20 0.81+0.82 o (18)Ov,r 0.23 0.87+0.80 1.90 MENCHETTI AND SABELLI: CAMPIGLIAITE 393 to water molecules, which assure the connection basici idrati: serpierite e devillite. Accademia Nazionale dei with the adjacent sheet only by hydrogen bonds. Lincei; Rendiconti della classedi Scienzefisiche, matematiche This ditrerence in the sheet stacking explains the e naturali, 43, 369-382. higher water content of campigliaite. Hamilton, W. C. (1959) On the isotropic temperature factor equivalent to a given anisotropic temperature factor. Acta Crystallographica, A27, 36E-j76. Acknowledgements International Tables for X-ray Crystallography, Vol. IV (1974) The authors would like to thank S. De Cassai (Miniera di Kynoch Press, Birmingham, England. Campiglia SpA) for samplingpermission; F. Conticini (Firenze) Mandarino, J. A. (1976)The Gladstone-Dalerelationship. Part I: for his collaboration in the field and laboratory work; L. Giannini derivation of new constants. CanadianMineralogist, 14, 498- and M. Ulivi (Firenze) for their assistencein SEM study; S. 502. Capedri and G. Garuti (Modena) for their collaboration in the Mellini, M. and Merlino, S. (197E)Ktenasite, another mineral analysiswith the electron microprobe equipmentof the Consiglio with -2 (Cu, Zn)2(OH)3Ol-octahedral sheets. Zeitschrift fiir Nazionale delle Ricerche, at the Istituto di Mineralogia e petro- Kristallographie, 147, 129-140. grafia dell'Universitd di Modena; A. Kato (Tokyo) for his helpful Mellini, M. and Merlino, S. (1979) Posnjakite: -2 [Cu4(OH)6 advice and suggestions. (HrO)Ol octahedral sheets in its structure. Zeitschrift fiir Kristallographie, 149, 249-257. References Nickel, E. H. (1976)New data on woodwardite. Mineralogical Magazine, 43, U4-&7. Baur, W. H. (1964)On the crystal chemistry of salt hydrates.IV. Palache, C., Berman, H. and Frondel, C. (1951)Dana's System The refinement of the crystal structure of MgSOa.TH2O(epso- of Mineralogy. Wiley, New York. mite). Acta Crystallographica, 17, 136l-1369. Rodolico, F. (1931) Osservazioni cristallografiche sulla ilvaite. Brown, J. D. and Shannon, R. D. (1973) Empirical bond- Periodico di Mineralogia, 2, 122-132. strength-bond-length curve for oxides. Acta Crystallogra_ Sabelli, C. and Zanazzi, P. F. (l%E) The crystal structure of phica. A29, 266-282. serpierite. Acta Crystallographica,B.24, 1214-1221. Conticini, F., Menchetti, S., Sabelli,C. and Trosti-Ferroni.R. Sabelli, C. and,Zanazzi, P. F. (192) The crystal structure of (1980) Minerali di alterazione dei giacimenti a solfuri misti di devillite. Acta Crystallographica,B2E, I 182-t I 89. Campiglia Marittima (Toscana).Rendiconti della Societd Ita- Shannon, R. D. and Prewitt, C. T. (1%9) Effective ionic radii in liana di Mineralogia e Petrologia, 36, 295-308. oxides and fluorides. Acta Crystallographica,B.25, 925-946. Donnay, G. and Donnay, J. D. H. (1973)Bond valence summa- tion for borates. Acta Crystallographica,829, 1417-1425. Manuscript received,April 16, 1981; Faraone, p. D., Sabelli, C. andZanazzi, F. (1967)Su due solfati acceptedfor publication, September17, 1981.