Jarosewichite and a Related Phase: Basic Manganese Arsenates of the Chlorophoenicite Group from Franklin, New Jersey
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American Mineralogist, Volume 67, pages 1043-1047,1962 Jarosewichite and a related phase: basic manganese arsenates of the chlorophoenicite group from Franklin, New Jersey Pe,re J. DUNN Department of Mineral Sciences Smit hsonian I nstit utio n Washington, D.C.20560 DoNelo R. Pr,econ Department of Geological Sciences University of Michigan Ann Arbor, Michigan 48109 PBrBn B. LBeveNs Department of Geology University of Delaware Newark, Delaware l97II eNo Wrllreu B. SIuuoNs Department of Earth Sciences University of New Orleans New Orleans. Louisiana 70148 Abstract Jarosewichite,Mn3+Mn3+(AsOn)(OH)0, is a new mineral, closely related to chloro- phoenicite,from the Franklin mine, Franklin, SussexCounty, New Jersey,where it occurs associatedwith andradite,franklinite, flinkite, cahniteand hausmannite.Jarosewichite is orthorhombic,space grotp C2lmLlm2lm,C222 or Cmm2,with a : 6.56(3),b : 25.20(10),c : 10.00(5)4,and Z : 8. The strongestlines in the X-ray powder difraction patternare (d, I, hkD2.669 100 222,082;3.91 60 042,061;1.788 50 (notindexed);2.503 30 242,261,004,0 l0 0. Jarosewichiteis dark red, occursin prismaticbarrel-shaped aggregates, has a density of 3.66(obs),3.70glcm3(calc).Itisbiaxial(-)withrefractiveindicesd= 1.780(5),p= 1.795(5)and y= 1.805(5);theorientationisX:a,Y: b,Z = c;pleochroismisweak,Z) X. Microprobeanalysis with Mn3+calculated, yields: FeO 0.4, MgO 2.l,CaO0.2,ZnO 1.2, MnO 42.3, Mn2O317.7 (IMn = 45.1 wt.%), AszOs24.0, with H2O 12.1 percent by difference,sum : 100.0percent. A secondmanganese arsenate from Franklin, New Jersey,is alsorelated to chlorophoen- icite, but may be heterogeneous.Although optical, chemicaland crystallographicproper- ties are characterized,there is sufficient ambiguity to deny it speciesstatus at this time. The data for this mineral, jarosewichite and chlorophoenicite imply the existence of a large family of related arsenates based on the structure principles outlined by Moore for chlorophoenicite. Introduction as carminitewithout providingthe datawhich led to this identification. However, the material did not In early 1981,Mrs. Alice Kraissl of River Edge, appear to have the usual appearanceof carminite New Jersey,called to our attention some dark red and an investigation of the assemblagewas under- crystals.They were then assumedto be carminite, taken. Our study revealed that it is not carminite associatedwith flinkite. The crystals had originally but that it is a new mineral, herein described as been noted by Cook (1973)and he describedthem jaroswichite. 0003-004)V82l09I 0- I M3$02. 00 1(X3 t0/,4 DUNN ET AL.: JAROSEWICHITE Jarosewichiteis named in honor of EugeneJar- hausmanniteand sharp euhedral crystals of cahnite osewich,chief chemistin the Departmentof Miner- and allactite. Cahnite is coated with a light brown al Sciencesat the SmithsonianInstitution, in recog- film and, in turn, with fascicles of flinkite and nition and appreciationof his many contributionsto jarosewichite,which appearto have formed at the mineralogythrough analysis of minerals,meteorites same time. Some jarosewichite encrusts flinkite, and rocks, and especially in the area of electron indicatingit was the last phaseformed. The associ- microprobe analysis. The mineral and the name ated minerals were identified by X-ray powder were approvedby the Commissionon New Miner- diffraction. als and Mineral Names, IMA. Type material is preservedin the SmithsonianInstitution undercata- Physicaland optical properties log # NMNH 148972.Identicalmaterial, obtained Jarosewichiteis dark red in color and appearsto from the same sample, is in the personal mineral be black except in thin splinters or crystals. The collection of Mrs. Alice Kraissl, who generously luster of fracture surfacesis sub-vitreousand the donatedthe type material.Another sampleis in the streak is reddish orange. Cleavage was not ob- MineralogicalMuseum at Harvard University (# served. The Mohs' hardnessis approximately 4. 109463)and is identical in every feature.Given the The density, determinedusing heavy liquid tech- fact that Mrs. Kraissl's materialwas obtainedfrom niques,is 3.66(4)glcm3, in excellentagreement with David Cook, who also provided the Harvard sam- the calculatedvalue of 3.70 glcm3. ple, it is likely that all thesesamples are parts of the Optically,jarosewichite is biaxial (-) with refrac- piece. original The Harvard sample is designated tiveindices o: 1.780(5),F:1.795(5) and 7: cotype. 1.805(5).2V could not be accuratelymeasured due Occurrence to minutecrystal sizeand the fact thatjarosewichite reacts with the refractive index liquids, a factor Jarosewichite occurs at the Franklin mine, which also causedthe high standardeffors in the Franklin, Sussex County, New Jersey. The type index determinations.2V calculatedfrom specimenwas collectedon the dumpsand nothingis "efractive the refractiveindices is 78". The orientationis X : known of its location in the mine. The specimen a, Y : b andZ: c. Pleochroismis weak, Z > X, consistsof massivegreen andradite intergrown with with Z : dark brownish : frankliniteof composition(Zn6.asMn6.a3Mgs.s3Fe6.s2 red and X medium brownish red. Calculation of the Gladstone-Dale Als.s1)l.e7FeihOr.sz.The ore is vuggy and the relationship, using the constants of Mandarino vugs are lined with a dark brown druse of an (1976)yields: Kc:0.224 andKp:0.217, indicat- unknown mineral, the X-ray powder diffraction ing excellentagreement of the analyticaland physi- pattern of which suggestsit is in the friedelite cal data (Mandarino, 1979).Jarosewichite does not group.Upon the brown druseare 0.5 mm crvstalsof respondto ultraviolet radiation. Most of the jarosewichite occurs as aggregates which are barrel-shaped,have a rough, irregular surface, and physically resemble some synadel- phite, particularly that from Sterling Hill. A few very small crystals, up to 0.5 mm in length, were observed.They are euhedralwith flattened habit, elongateon a, and tabular on b. The best crystals, for which only a limited number of faces could be observed for the [100] zone, have {010} as the dominantform and {021}as a less prominentform, as determinedusing a two-circle optical goniome- ter. A scanning electron photomicrograph of a divergentspray of jarosewichite crystals is shown as Figure 1. Chemical composition Fig. l. Radial divergent spray of prismatic jarosewichite Jarosewichite was chemically analyzed using an crystalswith bladedflinkite crystals, from Franklin, New Jersey. ARL-sEMeelectron microprobe utilizing an operat- DUNN ET AL.: JAROSEWICHITE lM5 ing voltageof 15 kV and a samplecurrent of 0.025 standard. The powder data, which were obtained pA, standardizedon brass.The standardsused for with a polycrystalline mount in a Gandolfi camera analysiswere manganite(Mn), synthetic olivenite using CuKa X-radiation, are listed in Table 1. The (As), syntheticZnO (Zn), andhornblende (Ca, Mg, number of unambiguouslyindexable reflections was Fe). No other elementswith atomic numbergreater not sufficient to permit least squaresrefinement of than 9 were found with a wavelength-dispersive the lattice parameters. scan.A spectrographicanalysis proved the absence All reflections having h or k odd are extremely of boron. Type chlorophoenicite(Dunn, l98l) was weak, and therefore were excluded from the proc- used as a control standard. Water could not be ess of indexing the powder pattern. These reflec- directly determineddue to extreme paucity of mate- tions are so weak that they are not discernibleon rial; it is calculatedby difference. The oxidation photographsobtained with very small crystals and stateof As is inferred from the As5+ presentin the very long exposures.There is thus a pronounced associatedcahnite and flinkite, both of which are substructurehaving cell parametersA-: 3.28(al2), intimately associatedwith jarosewichite. The oxi- B = 12.60$lD and C : 10.00 (c)A. The short dation state of Mn could likewise not be deter- translationof 3.3 A was shown by Moore (1968)to mined.We have assignedthe 4 Mn per formula unit occur in the structure of chlorophoenicite,(Mn, to Mnl+Mn3* using the Gladstone-Dalerelation- Mg)32n2(AsO4XOH)7,although in that case there ship as a guide. We infer the probablepresence of are streaksrequiring translationof 2 x 3.34. This someMn3* basedon: (a) the associatedflinkite and phaseis not only structurally and chemically similar hausmannitecontain Mn3* and Mn'*, indicating to jarosewichite,but also occurs at Franklin, New that the oxidation potential of the mineral-forming Jersey.Moore showed that the 3.34 translationin solutions was compatible with such oxidation chlorophoenicitecorresponds to the length of the states;(b) all associatedminerals have (OH) rather edge of a Mn-oxygen octahedron, resulting in a than H2O, the latter which would be necessaryfor chain of edge-sharingoctahedra of infinite lengthin jarosewichiteif all the Mn was Mn2*; and (c) the color and high absorptionofjarosewichite are con- Table l. X-ray powder diffraction data for jarosewichite sistent with the presence of Mn3*, which is an intenseabsorber in the visible range,either by itself d(uarc. rtl , o or through chargetransfer with Mn2*. 6.29 6. 30 040 20 The resultant analysis, with Mn3+ calculated, 5.30 5,33 041 5 yields:FeO 3.91 1 0t o42 60 0.4,MgO 2.1, CaO,0.2, ZnO,l.2,MnO 3.87 06r 42.3,Mn2O3 17.7 (Mn : 45.1 wt. Vo), As2O524.0 3.21 3.22 o23 5 o62 percent,with H2O l2.l percentby difference,sum 3.22 : 100.0percent. Calculationof unit cell contents, 3.17 3,15 080 2.669 2,680 222 t00 usingthe observeddensity and the unit cell parame- 2.665 082 2.612 2.6TT 063 ters, yields: [email protected]:Cq,oz2.573 2.585 260 2 Zns.s7)p3.1s(AsO+)o.qs(OH)u.351,with Z : 8, in excel- 2.503 2.520 0,10,0 30 lent agreementwith the theoretical end member 2.5L5 242 formula of jarosewichite, Mn3* Mn3* (AsOoXOH)u, 2.503 261 2.50r 004 for which the weight percents are Mn2O3 17.14, 2.451 2.453 024 10 : 2.444 0,10r1 MnO 46.20,As2O5 24.95, H2O 11.71,sum 100.00 2.289 2.299 5 percent.