Hedyphane from Franklin, New Jersey and Ling!

American Mineralogist, Volume 69, pages 920-927, l9A

Hedyphanefrom Franklin, New Jerseyand Ling!,an, Sweden: cation ordering in an arsenateapatiter

Rolexn C. Rouse Department of Geological Sciences University of Michigan, Ann Arbor, Michigan 46109

PBre J. DutrN Department of Mineral Sciences Smithsonian Institution, Washington, D. C. 20560

nNo DoNnr-n R. PEncon Department of Geological Sciences University of Michigan, Ann Arbor, Michigan 48109

Abstract

Hedyphane, traditionally formulated as (Ca,Pb)s(AsOr,POn)rCl,is redefined as Ca2Pb3(AsOahClwith Z : 2. The spacegroup is PQlm with a = 10.140(3)and c = 7.1E5(4)4.Observed and calculateddensities are 5.E5and 5.99 g/cm3,respectively. The crystal structurehas beenrefined to residualsof 0.062(weighted) and 0.076(unweighted) using 550 reflections.Ordering of Ca and Pb on equipoints4/ and 6h, respectively,is completeexcept for a possibleminor amountof solid solution(ca. lVo).Cation ordering in hedyphaneis attributed to a preferenceby atoms with sterically active electrcinlone pairs, e.g., Pb(II), for the asymmetricallycoordinated 6ft site. A study of mineralsin the solid solution series Ca"Pb5-*(AsOa)3Clfrom Lingban, Sweden, and Franklin, New Jersey, revealsa lack of compositionsin the range2.3 s x - 4.8, implyinga miscibilitygap in this regron.

Introduction lent cation sites.The A site correspondsto equipoint4/ In the course of a systematicstudy of lead calcium and is coordinatedby nine oxygen atoms at the vertices of arsenate apatites from Franklin, New Jersey, and a distorted tricapped trigonal prism, whereas the B site Ltngban, Sweden,two salient featuresappeared upon correspondsto equipoint 6/, with a coordination number tabulationof the chemical analyses.These features, a which dependson the identity of Z. That is, B is coordi- clusteringof analysesnear the ratio Pb:Ca = 3:2 and a natedby six oxygenand one Z atom when Z: F or OH conspicuouslack of compositionsin one regionalong the andby six oxygenand two Z atomswhenZ: Cl, Br, or I. Pbs(AsO+):Cl-Ca5(AsOa)3Cljoin, suggestedthat addi- (The cadmium apatitesare exceptionsto this rule (Sudar- tional study was warranted.The resultsof this investiga- sananet aI.,1977)). tion, in particular an analysis of the crystal structure of The segregationof cationsonto two nonequivalentsites hedyphane,have resulted in a redefinitionofthis mineral, creates a potential for ordering in mixed-cation apatites, which has heretofore held a rather ambiguous position the simplestpossible ordering scheme being AaBe. While within the apatite group. The data also permit some numerousapatites, both naturaland synthetic,exist with definition of the possiblelimits of solid solution in the this 4:6 ratio (Roy et al., 1978),very few have been systemPbs(AsO+)rCl-Cas(AsO+hCl. subjectedto crystal structure analysisto verify the order- The generalformula for the hexagonal(P6tlm) apatites ing implicit in their formulas. Moreover, such studies as may be written A4B6(XO4)622in recognition of the fact have been made have often relied upon powder X-ray that the structurecontains two symmetricallynonequiva- diffraction data to deduce the presenceor absenceof ordering. In this paper we present a crystal structure tContribution No. 388. The MineralogicalLaboratory, De- analysis based on single-crystaldata to demonstrate partmentof GeologicalSciences, University of Michigan. cation orderingof the 4:6 type in hedyphane. 0003-004x/84/09I 0-0920$02. 00 920 ROUSE ET AL.: HEDYPHANE 92r

Nomenclature barite, barylite, rhodonite, and numerousother phases. relatively few Llngban samples,we can- Hedyphane was originally described from the type Having studied than this simple paragenetic generaliza- locality, Lingban, Sweden,by Breithaupt(1830). It also not make more of a massive,fine- occursat the Harstig Mine, Pajsberg,Sweden (Igelstrcim, tion. The neotype specimenconsists grained, rock, which is coatedwith I cm lE65;Sjcalcite-bearing Theseare, in turn, coatedwith Franklin Mine, Franklin, SussexCounty, New Jersey, euhedralcalcite crystals. which euhedralindividuals from which it was described by Foshag and Gage (1925), hedyphanecrystals, occur as intergrown crystals. The Palacheand Berman (1927),and Palache(1935). Foshag and as clusters of randomly sparseamounts of allactite and and Gageproposed that hedyphanebe definedas material hedyphaneis followed by generations with Ca > Pb, leading to the formula (Ca,Pb)s(AsO+, two of hausmannite. hedyphaneoccurs in a wide variety of PO4)3C1,which is the one given in most modernmineral- At Franklin, non-silicatelead ogical compendia. However, our electron microprobe assemblagesand is the most abundant both in terms of volume and survey of a large number of specimensfrom Franklin and mineral at this deposit, the representative Lingban, some analysesof which are presentedherein, frequency of occurrence. Among Franklin hedyphane are (a) As hasfailed to produceany lead-bearingspecimens which modes of occurrence of yellow greasy-lusteredmaterial conform to the criterion of Foshagand Gage.This calls massive, to colorless, and curved, platey, into question the chemical analysispublished by these associatedwith barylite, copper, massive (b) As colorless,yellow, or gray tabular authors,who, in fact, noted that some of their material calcite. barite, and man- appearedto be slightly altered.Unfortunately, we were dipyramidsassociated with rhodonite, ganaxinite. these euhedralcrystals unable to locate the specimenthey studied and thus it The morphology of (1927) could not be reanalyzed. was describedby Palacheand Berman and Palache (1935).(c) As yellow-to-brown-to-graymassive materi- The Ca > Pb criterion of Foshagand Gagecreates a a in willemite-franklinite ore and dilemma when one tries to formally define hedyphane. al, filling fracture seams with rhodonite. (d) As stout, pris- Although these authors proposed that hedyphane be frequentlyassociated x 6 mm in size, associated consideredthe namefor materialwith Ca > Pb, they were matic, colorlesscrystals, 6 with green willemite, bright pink rhodonite, and discussingtheir own material and not other, previously bright The last-namedassemblage describedhedyphanes, all of which contain substantial copper, all in a calcite matrix. and coats a pre-existing,strongly amountsof lead and whose Pb: Ca molar ratios approxi- is clearly secondary undeterminedcomposition. mate3:2. We thereforepropose that the namehedyphane fluorescentapatite of be restrictedto material which meets the following re- quirements:that Pb and Ca be major elementshaving a Physical description -3:2, molarratio of that As exceedP, and that Cl exceed The neotypehedyphane occurs as light yellow, euhe- F or (OH). Defined in this way, the ideal formula of dral crystals approximately I mm in maximum dimen- hedyphanebecomes Ca2Pb3(AsOahCl. previ- The niche sion. They are tabular on {0001},and the form develop- ously assignedto this mineral,namely (Ca,Pb)5(AsOa)3Cl ment is similar to that figured by Palache and Berman with Ca > Pb, or ideally the end-memberCa5(AsOa)3CI, (1927). The morphologies of the Swedish and Franklin is now vacant. Material with this ideal end-member crystals are similar. Hedyphane is translucent with a compositionhas been discovered,however, and is now white streakand hasa greasyto vitreousluster on crystal beingcharacterized. When this is accomplished,it will fill faces and fracture surfaces. The Mohs hardness is ap- the niche previously assignedto hedyphaneby Foshag proximately4. Cleavageis indiscernible,the fracture is and Cage.This nomenclaturalscheme is advantageousin even, and the mineral is moderately brittle. Density that it retainsthe namehedyphane for thosecompositions measurementsmade with a Bermanbalance gave values previouslydescribed as hedyphanein the literature,thus rangingfrom 5.71 to 5.85 g/cm3. with the latter value ensuringcontinuity. This redefinitionof hedyphanewas closest to that calculated from the ideal formula, namely proposedto the IMA Commissionon New Minerals and 5.99 glcm3. Optically, neotype hedyphane is uniaxial Mineral Names as part of a submissionon turneaureite positivewith a meanindex of refractionbetween l 95 and and has been approvedby that body. 1.965.The observation is in agreementwith those of We have chosenfor the neotypehedyphane the Har- Palache and Berman (1927), who found Franklin hedy- vard University specimenH-90411 , from Lflngban,Swe- phaneto have indices e = 1.958and ar = 1.948. den. Material from this specimenhas been used in a Although the arsenateapatites from Franklin cannot, in determinationof the crystalstructure and for the determi- general,be unambiguouslyidentified on the basisof their nation of the chemical,unit cell, and spacegroup data variedresponses to ultravioletradiation, the lead-bearing presentedherein. members(mimetite and hedyphane)have a very weak, Occurrence light yellow fluorescence.Johnbaumite, Cas(AsO+)rOH, Hedyphaneoccurs at Lingban both in massiveform showsa strongorange fluorescence, which is characteris- and as euhedralcrystals. It is frequentlyassociated with tic of this mineral. 922 ROUSE ET AL.: HEDYPHANE

Chemistry and X-ray crystallography Table2. Electronmicroprobe analyses ofhedyphane and related speciesfrom Lingban, Sweden The sampleswere chemicallyanalyzed using an anl- seuq electron microprobe utilizing an operating voltage specimen cao BaO Pbo Pz0s As205 cl 0=cl'F Total of 15kV and a samplecurrent of 0.025g,A, measuredon brass. The standardsused were synthetic PbO (Pb), 134981 43.8 0.7 6.I 44.9 3.2 1.2 'ltoo.el B13f7l 42.9 1.2 2.2 50.r 2.4 1.1 '101.9oo.7o fluorapatite(Ca, F, P), barite (Ba), celestite(Sr), scapo- H105545 12.0 0.1 57,8 0.4 29.0 3.4 0.8 l'lichaelson 10.50 57.45 3.I 9 28.51 3.06 0.59 '100.6102.02r lite (Cl), manganite(Mn), and arsenolite(As). The data H90417 10.3 0.1 58.0 0.4 28.2 3.3 0.7 " were correctedusing a modified version of the uecrc-4 100.2 R5302-3 ',1010.2 ',l4.4.7 54.0 0.2 28.5 3.3 0.7 program.Zn is absentin all samplesstudied. The result- 48983 .0 I 46.0 o.s 25.3 3.4 0.8 98.s . Hedyphane L72 58.02 'f 29.88 3.07 0.69 100.00- ant analyses,together with previous analysesof hedy- R10663 9,6 4.9 55.I .0 27.4 2.8 0.6 100.2 H88066 9.6 3.s 56.3 0.3 28.4 3.3 0.7 100.7 phane, are presented in Tables I and 2 in order of decreasing c4148 9.1 5.0 57.3 27.9 3.2 0.7 101.8 calciumcontent. PAl4301 8.8 il.z 49.3 0.9 27.5 2.8 0.6 99.9 A The unit cell contents of neotype hedyphane(H-9[.4n), Lindstrim(1879) 7,85 8.27 50.89 0.55 29.01 3.14 0.71 99.57- Hll63i3 7.6 l1.4 52.5 1.3 26.5 3.2 0.7 l0'l.8 calculated assuming a density of 5.85 glcm3, are Hl0l553 6.9 0.3 63.6 0.2 25.3 3.I 0.7 98.7 Caa1Pb5 sSrs 2As5 5Ps 1O23.2C12.1 or, ideally, Ca2Pb3(As PAl3g5',t 6.0 0.4 66.3 0.2 24.8 3.0 0.7 100.0 : H116366 5.4 1.0 65.3 |.0 24.5 2.9 0.7 99.4. O+)rClwith Z 2. X-ray powder difraction data were lilireti te 74.99 23.172.38 0.54 100.0' obtained from the same sample utilizing a 114.6 mm diameter Gandolfi camera, a polycrystalline sample, "lncludes l.9S l4n0and 1,21 F 1n 134981and 1.7%Mno and 1.3? F in Bl3l7l. CuKa radiation,and NBS (a : blnc'ludes silicon 5.43088A)as an l.o1 sro. This cdnponentwas not found in other specrmens. cTheoretical internalstandard. The data are given in Table 3. composition of hedyphane,ca2Pb3(Aso4)3c1. A Fragments of a euhedral crystal from the same speci- "lnc'ludes0.25% 1|90, 0.08% Fe203, 0.15u Na20,and 0.09t KZo. men were studiedby the precessionmethod using MoKc "Theoretical compositionof nimetite, Pb5(As04)3C1. radiation.The group Accuracyof microprobedata is + 4g of the amountpresent. Fluorlne space of hedyphaneis Pglm, the is absent or present in traces except as noted. crystal structure having been refined successfullyin this symmetry. No monoclinic superstructure reflections were evident on overexposedprecession photographs takenwith unfilteredradiation. The unit cell parameters, and Pbs(AsOr)rCl(Kreidler and Hummel 1970),namely refinedby least-squaresfrom the powder data in Table l, a:10.16andc:7.204. area = 10.140(3)and c : 7.185(4)A.These values are in good agreementwith those calculated from weighted Structure refinement averagesof the cell parametersof syntheticCa5(AsOa)3Cl A crystal fragmentapproximately 0.12 x 0.12 x 0.22 mm in size from specimen H-90417 was chosen for structureanalysis. The intensitiesof 550reflections hav- Tablel. Electronmicroprobe analyses of hedyphaneand related ing sinO < 0.460 were measuredwith a Supper-Pace speciesfrom Franklin,New Jersey diffractometersystem using Weissenberg equi-inclination Specimen Cao Sr0 Bao Pbo PZoS As205 Cl o=Cl,F Total geometry, monochromatizedMoKa radiation, and a scanning rate of 2olmin. Intensities of four standard c6270-1 45.4 '11.4 8.5 42.5 2.1 0.8 roo.ul c6270-2 45. I .5 7.9 nq oooo reflections were periodically monitored throughout the Foshag(1925)14.98 52.77 29.94 2.98 o.iz roo.aol data-gatheringprocess to check crystal and electronic c6277-1 1l.l 0.8 0.4 56.0 0.4 28.8 3.3 0.7 100.5" c4145 10.6 3.5 0.8 51.2 0.3 30.I 3.3 0.7 99.1 stability. The data were converted to structure factor H90003 10.0 3.4 0.3 54.2 0.3 28.7 3.4 0.8 99.5 amplitudesby correction for Lorentz, polarization,and -3 R5301 9.8 6.6 0.9 50.0 0.3 30.2 3.5 0.8 100.5, = Hedyphane 9.72 58.02 29.88 3.07 0.69 100.00" absorptioneffects (/.r 475 cm-t). A total of 57 reflec- c6?76 9.5 4.4 l.l 52.2 0.3 29.1 3.3 0.7 99.2 tions were unobservedand assignedintensities of 1-;n/3, H107890 9.1 7,0 0.5 52.0 0.2 29.1 3.4 0.8 100.5 where 1-1nis the minimum observableintensity. Struc- H97913 9.0 6.9 0.6 52.0 0.2 29.5 3.4 0.8 100.8 R5301-l 8.9 6. 1 0.8 51.2 0.2 29.2 3.3 o.7 99.0 ture factor calculationswere carried out with the program R6552 8.2 0.9 0.6 59.3 0.6 27.2 3.1 0,7 99.2 H90006 (Finger, 7.9 8.4'1.2 0.4 52.5 0,2 29.9 3.3 0.7 101.9 RFINE2 1972) using neutral atom scattering H105459 7.1 0.3 63.4 0.8 26.4 3.1 0.7 ]0l.6 factors (Doyle and Turner, 1968),anomalous dispersion 'l.l '| H105462 5.9 1.4 62.2 .3 24.0 3.0 0.7 98.2 correctionsfor Pb and As (Cromerand Liberman, 1970), 14iretite 74.99 23.17 2.38 0.54 100.00-" the reciprocalvariances of the lFlo6,as weights,and the alncludes O.6Xllno, O.8t F, traces of Bao,and 0.2%H"0 (in C6Z7O-1). atomiccoordinates in mimetite(Hendricks et al., 1932)as ^a "Includes0.282 (Feo + t4n0),0.109Mso,0.23% 2n0,0.081 H^0, and o.17% initial values for the positional parameters.Ca and Pb insoluble residue. clncludes 0.5%MnO. wereassumed to be fully orderedin 4/and 6ft, respective- oTheoretical cmposition of hedyphane,Cazpb3(Aso4)3C]. ly, asimplied by the composition.Unobserved reflections eTheoretical cmposition of nimetite, eusietd4)rci." were assignedzero weight during the refinement. .is Accuracyof microprobedata is I 4g of amountpresent- Fluorine Using isotropic temperaturefactors, the refinement absent or present in traces excEpt as noted. converged to an unweighted conventional residual of ROUSE ET AL.: HEDYPHANE 923

Table 3. X-ray powder ditrraction data for hedyphane eters with theseoccupancy factors causedthe temperature factor of Ca, which had refinedto a value of 0.0142 I dobsd dca'lc hkl I dobsd dcal hkl c in the completelyordered model, to increaseto a some- what more reasonablevalue of 0.2842.For this reason, 4 8.77 8.78 100 f r .7og 3t3

Table4. Atomic coordinatesand anisotropic temperature factors (x l0a) in hedyphane

'33a a 'I I Bzz "12 "t3 "23

ca 1/3 2/3 0.009(I ) 7(7') 1(7\ le(18) 3(3) 0 o 0.3(2)

Pb 0.258r( 2) 0.0r42( 2) 1/4 l8(2) 27(2) 5e(3) t0(2) 0 0 0.97(4)

As 0.4021(4) 0.389s(4) 114 8(s) 8(s) 4o(8) I t5J 0 0 0.48(7) 0(r) 0.364(3) 0.523(3) 1/4 -ro(5) 1r(35) 72(66) l(30) o o 0.2(s)

0(2) 0.616(3) 0.474(3) 1/4 37(40 ) ss(45) l 5(62) 32G7) 0 0 0.3(5) 0(3) 0.365(3) 0.276(2) 0.06s(3) il9(40) 5r(32) r63(62) 73(3r) -r33(3e) -7e(3s) I.7(5)

cl 000 58(15) 58(16) 30(37) 2e(8) 0 0 1.2(3)

Estimatedstandard deviations are in parentheses. Theanisotropic temperaturefactors (B) are of the form 33 exp {- I E hrhjBrr}. Isotropic temperaturefactors (B) are from the final cycle of the isotropic refinement. i-r i-r I J rJ r-t J-l 924 ROUSE ET AL.: HEDYPHANE

Table 5. Selectedinteratomic distances(A) and angles(.) in unreasonablylarge and its rms thermal displacement hedyphane along the c axis is only 0.0904, indicatingno displacement from the ideal positions. This accounts for the polyhedron Ca09 maintenanceof hexagonalsymmetry in hedyphane,since ca-o(l ) 2.38(2) (3x) chlorine displacementswould produce a monoclinic su- o(2) 2.ss(z\ (3x) perstructure with a doubling of one of the a cell dimen- 0(3) 2.86(21(3x) mean 2.60 sionsas in chlorapatite. In addition to orderingphenomena, some comment is Pbo5Cl2polyhedron necessaryconcerning the changesin the position of the Pb-o(2) 2.36(3) o(2)-Pb-o(3) 85.8(6)(2x) O(l) atom in hedyphane,vanadinite (Pb5(VOa)3Cl), and 0(3) 2.s4l2l (zx't 0(3)-Pb-o(3)r26.2(r.1) finnemanite(Pbs(AsOr)lCl) and the consequencesfor o(3) 2.67(2)(2x) mean 99.3 cation coordinationin thesechlorapatite isotypes. Com- Pb-o(r) 3.45(2)(2x) parisons with mimetite (Pbs(AsO+):Cl)and pyromorphite c'l 3.il7(2)(2x) (Pb5(PO4)3Cl)would also be usefulhere, but well-refined As04 tetrahedrcn structuresare not availablefor theseminerals. In vanadi-

As-0(3) 1.66(2)(2x) 0(3)-As-0(2) 104(l) (2x) nite (Trotter and Barnes, 1958)the longestPb-O bond is o(l) 1.70(2) 0(3)-As-0(3) 106(2) between Pb(2) (which correspondsto the Pb site in 0(21 r.73(3) 0(l)-As-0(2) lll(l) hedyphane)and O(l) at 3.17(6)4. A secondPb(2)-O(l) mean 1.69 0(3)-As-o(l) lls(l) (2x) distanceof 3.80(4)4is too long to representa chemical rean 109 bond. In hedyphane the Pb-O(l) distance is further 0(3)-0(3) 2.66(51 lengthenedto 3.45Q)A(two equal distances),which rep- 0(2)-0(3) 2.68(3)(2xl resentsa very weak interactionat The 0(l)-0(3) 2.83(3)(2x) best. Pb atom in o(r)-o(2) 2.83(4) hedyphaneis thereforeessentially in 7-fold coordination (Fig. l), rather than the 8-fold coordination usual in Shortest distances chlorapatiteisotypes. The limiting case occurs in finne- Ca-Ca 3.46(2) As-As 4. I l4(4) manite (Effenbergerand Pertlik, 1979\,in which O(l) is Pb-Pb 4.404(2) cl-cl 3.593(2) altogether absent from the structure, leaving Pb(2) in an Pb-Ca 4.208(s) 0(3)-cr 3.38(2) unambiguous7-fold coordindtion, AsO3 trigonal pyra- ca-As 3.387(6) 0(3)-0(3) 2.66(s) Pb-As 3.305(4) mids rather than AsOa tetrahedra,and Pb(l)zOsgroups, which stronglyresemble Pb-Pb metal clusters. Estinated standard devlations are in parentheses. Twoand If the two O(l) atomsin Figure I are not bondedto Pb, three identical distances are denoted by 2X and 3x, respectively it is obviousthat the lead atom hasa decidedlyasymmet- rical, "one-sided" coordination.It is alsoperhaps signifi- hedyphane.The hexagonal polymorph of caracolite, for cant that the shortest and presumably strongestPFO example,has 4 Na in 4/and (4pb + 2Na) in 6h (Schneider, bond, that to O(2) at 2.36(2)4, is apposedto the two 1967). distant,nonbonded O(l) atoms.This one-sidedcoordina- Of the synthetic apatites with a 3:2 cation ratio, tion of Pb(II) is very commonand is usuallyattributed to ordering has been confirmed experimentally in only a repulsionsbetween a sterically active 6s2electron lone few. One suchcase is CaqPbe@Oe)o(OH)2,which Engelet pair on the lead atom and the neighboringanions (Galy et (1975) al. found to be fully orderedwith Ca in 4/and pb in al., 1975).In the structuresof hedyphaneand vanadinite 6ft as in hedyphane.By contrast, Cockbain and Smith (andprobably the other leadchloride apatites as well), the (1967) found CarLar(SiO+)o(OH)zto be disordered.Un- lone pair is presumably directed towards the two distant fortunately, both of these determinations are subject to O(l) atoms.On the other hand,in vanadinitethe lone pair somedoubt, as they were derivedfrom analysisofa very efect is not manifestin the environmentof the Pb(l) atom small numberof powder X-ray reflections.A full crystal (which correspondsto the Ca site in hedyphane).The structureanalysis of an apatite of the 2:8 type, Ca2l-ag Pb(l)-O distancesare 2.47, 2.57, and 2.764, which are (SiO4)6O2, was performed by Schroeder and Mathew less than or equal to the sum of the ionic radii for 9- (1978), who found (2Ca + 2La) in 4f and 6 La in 6ft. This coordinatedPb2* (Shannon,1976),and the coordination is the inverseof the orderingin caracolitein the sensethat polyhedron (a distorted tricapped trigonal prism) is very the 4-fold rather than the 6-fold site has mixed occupan- like that aroundthe analogousCa(l) site in chlorapatite,a cy. mineralwhich containsno lone pair ions. Although cation ordering has been demonstrated in If the structure of hexagonalchlorapatite (Brosnahan, hedyphane,there is no evidencefor displacementof the 1977)is regardedas the prototype for those of hedyphane chlorine atoms from their ideal positions at 0,0,0 and and its congeners,a comparisonof the Ca(l) and Ca(2) 0,0,Vzasis the casein monoclinicchlorapatite (Mackie et coordination polyhedra in chlorapatite suggestsa reason al.,1972). The temperaturefactors ofthe Cl atom are not why hedyphane and CaaPb6@Oa)6(OH)2have ordered ROUSE ET AL.: HEDYPHANE 925

o(3)

@ o0) o(3)

o(2) o(2) O(2)

Fig. 3. Projection on (100) of the coordination polyhedron Fig. (lCO) the polyhedron l. Projectionon of coordination around the Ca(l) site in chlorapatite. Numerals within the circles within aroundthe Pb site in hedyphane.Numerals thecircles are are the -r coordinatesof the atoms. thex coordinatesof the atoms. hence there is no strong site preference, and Caz* and cations,while Ca

tant implicationsfor solid solutionsin other apatites.Few Breithaupt,A. (1830)Bestimmung neuer Mineral-Specien,2. structuresexhibit such a wide range of ionic substitutions Hedyphan.Journal ftir Chemie und Physik, Nuremberg,60, as does the apatite structure (nearly half the elementsin 30E-316. the periodic table according to Roy et al. (197g)).In Brosnahan, D. R. (1977) High Temperature Single-Crystal X- particular, it may be predicted from the apparent special Ray Diffraction Study of Monoclinic Chlorapatite. M.S. The- compatibility of the 6ft site with large cations having sis, Universityof Michigan,Ann Arbor. Cockbain,A. G. and Smith, V. (1967) nonbonded valence electron pairs that such atoms will G. Alkaline-rare-earth silicate and germanateapatites. Mineralogical Magazine, 36, always exhibit a preferencefor this site. At least partial a 4ll-421. orderingof Pb(II), Sn(II), B(IID, Sb(IID, Tl(I), Ge(II), Cromer, D. T. and Liberman, D. (1970)Relativistic calculation and Te(IV), where they occur in the apatite structure, of anomalousscattering factors for x-rays. Journal of Chemi- may be expected.This may, in turn, affect physicaland cal Physics,53, 189l-1898. chemical properties. One example is the property of Doyle, P. A. and Turner, P. S. (1968)Relativistic Hartree-Fock luminescence,if the structure contains activator ions in x-ray and electron scatteringfactors. Acta Crystallographica, addition to the lone pair atoms listed above. In fact, 424,390-397. Sb(IID is itself an activator in apatites and has been Dunn, P. J., Peacor,D. R., and Newberry, N. (1980)Johnbau- proposed to preferentially occupy the 6/r site, albeit for mite, a new member of the apatite group from Franklin, New Jersey.American Mineralogist, reasonsother than the one given here (Blasse, 1975).A 65, I 143-l I 45. Dunn, P. J., and Rouse,R. C. (1978)Morelandite, a new barium secondexample is the degreeof uptake of toxic elements arsenate chloride member of the apatite group. Canadian into the apatite of human bones and teeth. All of the Mineralogist,16, 601-604. aforementionedelements exhibit heavy metal toxicity in Effenberger, H. and Pertlik, F" (1979)Die Kristallstruktur des humans in varying degrees. Finnemanits, Pb5Cl(AsO3)3,mit einem Vergleich zum Struk- Insofar as the minor elements in hedyphane are con- turtyp des Chlorapatits, CasCl(POa):.Tschermaks Mineralo- cerned, Tables I and 2 show that Sr is the chief cationic gischeund PetrographischeMitteilungen, 26, 95-107. substituentin Franklin hedyphanes,whereas at L6ngban, Engel, G., Kreig, F., and Reii c. (1975)Mischkristallbildung this role is filled by Ba. The maximum SrO contenr und Kationenordnungim System Bleihydroxylaparit-Calcium- observedin hedyphaneis 8.4 wt.%o,equivalent to 0.gg Sr hydroxylapatit.Journal of SolidState Chemistry, 15, 117-126. Finger, L. W. (1972)nrrNe per 5 total cations. The maximum BaO content is 22 2: A Fortran IV computer program for structure factor calculation and least-squaresrefinement of wt.Vo, eqvivalent to 1.5 Ba per 5 total cations, this being crystal structures. Geophysical Laboratory, Washington, in an unpublishedanalysis. Both Ba and Sr substitutefor D. C. Pb, as shown by sympathetic variations among these Foshag,W. F. and Gage,R. B. (1925)Hedyphane from Franklin elements.This is consistentwith their ionic radii, which Furnace,New Jersey.American Mineralogist, 10, 351-353. favor their substitution for Pb rather than Ca. No samples Galy, J., Meunier, G., Andersson,S., and Astrcjrm,A. (1975) were found with Ba > Pb; such material would be St€r6ochemiedes €ldments comportant des paires non li€es: classified as morelandite,(Ba,pb,Ca)5(AsOa)3C1, a miner- Ge(II), As(III), Se(Iv), Br(V), Sn(II), Sb(IID, Te(IV), I(V), al currently known only from Jakobsberg,Sweden (Dunn Xe(VI), T(I), Pb(ID, et Bi(III) (oxydes, fluorures et oxyfluor- and Rouse, 1978). ures).Journal of Solid StateChemistry, 13, 142-159. Giuseppetti, Based on the previous definition of these arsenate G., Rossi, G., and Tadini, C. (1971)The crystal structure of nasonite. American Mineralogist, 56, 1174-1179. apatites,i.e., (ca,Pb)5(Asor)rclcompositions with ca > Hendricks,S. B., Jefferson,M. 8., Mosley, V. M. (1932)The Pb being hedyphaneand those with pb > Ca being crystal structures of some natural and synthetic apatiteJike mimetite, Dunn et al. (1980) reported that most of the substances.Zeitschrift fiir Kristallographie, 8l, 352-369. material from Franklin and Lingban was calcian mime- Igelstrcim,L. J. (1865)Nya och siillsynta mineralier frin Verm- tite. That statement must now be revised in light of the land. Svenska VetenskapsakademienStockholm Handlingar, recognition of hedyphaneas an ordered speciesinterme- )) ))1J)O diate between the unnamed species Ca5(AsOa)3Cland Kreidler,E. R. and Hummel, F. A. (1970)The crysralchemistry Pbs(AsOnhCl(mimetite). Most of the specimensde- of apatite: Structure fields of fluor- and chlorapatite. American scribedby Dunn et al. are now shownto be hedyphane.It Mineralogist,55, 170-184. Lindstrdm, (1879) should be noted, however, that true mimetite does. in G. Barythaltig hedyphanfrin Lingban. Geo- logiska Foreningens fact, occur at both Franklin and Lingban. Ftirhandlingar, Stockholm, 4, 266. Mackie,P. E., Elliot, J. C., and Young,R. A. (1972)Monoclinic Acknowledgments structure of synthetic Cas(POr)rCl,chlorapatite. Acta Crystal- lographica,B2E, The authorswish to thankDr. SubrataGhose and especially 1840-1848. Dr. PaulB. Moorefor their carefuland criticalreviews of the Michaelson. Undated analysis given in Rammelsberg, C. F. manuscript. (1875) Handbuch der Mineralchemie, Verlag Engelmann, Leipzig, p. 337. References Palache, C. (1935)The minerals of Franklin and Sterling Hill, Blasse,G. (1975)Influence oflocal chargecompensation on site SussexCounty, New Jersey.U.S. GeologicalSurvey profes- occupationand luminescenceof apatites.Journal of Solid sional Paper 180. statechemisrry, 14, lgl-1E4. Palache,C. and Berman, H. (1927) Crystallographic notes. I. ROUSE ET AL.: HEDYPHANE 927

Phosphophyllite;2. Hematite; 3. Willemite; 4. Hedyphane. Sudarsanan,K., Young, R. A., and Wilson, A. J. C. (1977)The 'apatites' AmericanMineralogist, 12, 180-187. structuresof somecadmium Cds(MO4)$.I. Deter- Roy, D. M., Drafall, L. E., and Roy, R. (1978)Crystal chemis- mination of the structures of Cds(VO+)rI, Cds(PO+)rBr,Cds try, crystal growth, and phaseequilibria of apatites. In A. M. (AsO+)rBrand Cds(VOa)3Br.Acta Crystallographica'B33' Alper, Ed., PhaseDiagrams, Volume 5, 185-239.Academic 3136-3142. Press.New York. Tazzoli,V. (1983)The crystalstructure ofcesanite, Ca1**Naa-*- Schneider,W. (1967)Caracolit, das NarPbz(SO4)3Clmit Apatit- (SO4)3(OH).' (l -x)HzO, a sulfateisotypic to apatite.Miner- struktur. Neues Jahrbuch fiir Mineralogie Monatshefte, 284- alogical Magazine,4T, 59-63. 298. Trotter, J. andBarnes, W. H. (1958)The structureof vanadinite. Schneider,W. (l%9) Bestimmungeiner Uberstrukturam Cara- CanadianMineralogist, 6, 161-173. colit. Neues Jahrbuch ftr Mineralogie Monatshefte, 58-67. Verbeeck,R. M. H., Lassuyt,C. J., Heiiligers,H. J' M.' Schroeder, L. W. and Mathew, M. (1978) Cation ordering in Driessens,F. C. M., and Vrolijk, J. W. G. A. (1981)Lattice CazLaa(SiOa)eO2.Journal of Solid State Chemistry, 26, 383- parametersand cation distribution of solid solutionsof calcium 387. and lead hydroxyapatite. Calcified Tissue International, 33' Shannon,R. D. (1976)Revised efective ionic radii and systemat- 243-247. ic studies of interatomic distances in halides and chalcogen- ides.Acta Crystallographica,A32, 751J67. Sj