DOCSLIB.ORG

Petersite, a REE and Phosphate Analog of Mixite

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Petersite, a REE and Phosphate Analog of Mixite American Mineralogist, Volume 67, pages 1039-142, l9E2 Petersite,a REE and phosphateanalog of mixite DoNer-o R. PBecon Department of Geological Sciences University of Michigan Ann Arbor, Michigan 48109 nNn PBIB J. DUNN Department of Mineral Sciences Smithsonian Institution Washington, D.C.20560 Abstract The new mineral petersite (Y,REE,Ca)Cuo@Oa)I(OH)6.3H2O)occurs as a supergene mineral at the traprock quarry at Laurel Hill in Secaucus,New Jersey. It occurs in a brecciatedand mineralizedhornfels near a diabasecontact, in associationwith opal and malachite.Prismatic crystals less than 0. I mm in lengthwith forms {1010}and {0001}occur as radiatingsprays. It is optically uniaxial, positive,with or : 1.666(4) and e: 1.747(4). The measureddensity is 3.41g/cm3. Petersite is hexagonal,probable space group PQlm or P63,with a : 13.288(5)c : 5.877(5)4,V : 898.6(8)43,and Z:2.The strongestlines in the powderdiffraction pattern are: (d, intensity,index) I1.6, 100,100; 4.36, 50, 210;3.49,40, 2ll;2.877,40, 400;2.433, 60,212. The nameis in honorof Thomasand JosephPeters. Introduction under catalog # NMNH 148973at the Smithsonian Institution. The new mineral describedherein was sent to us for examinationby Mr. ThomasPeters of the Pater- Morphology son Museum,who had obtainedit from Mr. Nicho- Petersiteoccurs as prismatic hexagonalcrystals las Facciolla, who found it in early 1981. Mr. of simplemorphology. The only forms presentare Peters'examination by SEM techniquessuggested the prism {1010}, and the pinacoid {0001}. The a hexagonal morphology for the mineral and our crystals are usually euhedral and occur in radiating subsequentX-ray diffraction study showedit to be clustersand sprayswhich are somewhatisolated on hexagonaland isostructural with members of the the matrix (Fig. 1).Radial aggregates, which consist mixite group. Preliminary electron microprobe data of a large number of prismatic crystals (Fig. 2), showed that phosphorus is present as a major appear hemispherical and slightly dull due to a dull elementbut that arsenicis not present.A detailed luster on the exposedpinacoids, as comparedwith examinationhas confirmedthat it is a new member the highly vitreous luster on the lessexposed prism of the mixite group, and that it is the first phosphate faces.The habit of petersiteis in markedcontrast to analogueof this group of arsenates. that of the arsenatemembers of the series, gou- We take greatpleasure in namingthis new miner- deyite, mixite, and agardite,which usually occur in al petersitein honor of Messers.Thomas and Jo- wispy aggregatesof extremely acicular crystals. sephPeters, brothers, in recognitionof their contri- The maximum size of crystals examinedwas less butions to the mineralogyof New Jerseyand their than 0.1 mm in length, and most are considerably devotion to curating at the Paterson Museum in smaller. The diameter of radiating clusters ap- Paterson,New Jersey,and the American Museum proaches0.1 mm (Fig. 2). of Natural History in New York, respectively.The mineral and the name were approved by the IMA X-ray crystallography Commissionon New Minerals and Mineral Names, Single crystals were studied using Weissenberg prior to publication. Type material is preserved techniques. The resulting photographs confirmed 0003--004>v8?109l 0- l 039$02. 00 1039 1040 PEACOR AND DUNN: PETERSITE Table l. X-ray powder ditrraction data for petersite, obtained usinga 114.6mm diameterGandolfi camera d(Obs) d(Calc.) hkl' t/Io* d(Obs.) d(Calc.) hk'l !llo 11.6 11.s 100 100 L.767 I.769 332 10 4.36 4.35 210 50 I.742 I.745 303 20 4.12 4.11 201 10 r .687 1.691 512 I5 3,84 3.84 300 i0 1.687 223 3.49 3.50 2tr 40 1.659 1.661 440 2 3.32 3.32 220 t0 1.603 1.606 602 c 1 10 1 lO 310 5 I.598 441 2.877 2,877 400 40 1.583 1.583 531 2.806 2.805 311 10 1.583 701 2.687 2.697 tLz 10 1.559 l.561 522 2.634 2.640 320 15 1.523 L.524 710 2.509 2.511 410 30 1.505 1.507 6L2 2.433 2.435 2L2 60 1.466 1.469 004 2.411 2.408 321 1 L467 JJJ 2.197 2.201 222 5 I.444 1.445 442 z, lot z. loz 'La 2 1.403 1.406 720 2.051 2.162 510 2 1.402 622 2.056 402 1.394 t.397 80r Fig. l. Scanning electron microscope photomicrograph t.961 1.964 i22- 2_0 L.39?- 2r4 1.888 1.892 430 1 1.265 r.268 722 15 showingdivergent radiating spray of petersitecrystals. I.268 414 L.ZOI 443 1.264 731 that petersiteis hexagonal,with point group sym- metry 6lm. Extinctions occurredfor 00/ reflections *Intensities visually estimated. 'Indexed having I : 2n * l However, as all crystals are on^thebasis of a hexagonalunit cell with a=13.228(5)and exceptionally small and the reflections are very c=5.877(5)X. weak even for very long exposures,this extinction rule is not as well defined as we would like. Assuming that it is present, however, the space agreementwith other membersof the mixite group. group must be PQlm or P63. For example, Wise (1978) reports the probable Powder diffraction data were obtained using a spacegroup of goudeyiteas P63lmor P63, with a : : polycrystallinesample in a Gandolfi camera(114.6 13.472(l)and c 5.902U1A. mm diameter),CuKa radiation, and Si as an inter- properties nal standard.The data are presentedin Table 1. Physicaland optical Unit cell parameters(a : 13.288(5),c : 5.877(5)A Petersiteis bright yellowish green in color, quite V : 898.6(8)43)were obtained through leasr- similar in hue to cuprosklowdowskite.The hard- squaresrefinement of the powder diffraction data. nesscould not be determineddue to the very small These crystallographic parameters are in general crystal size and a high degree of brittleness.The density, obtainedusing heavy liquid techniques,is 3.41glcm3, in excellentagreement with the calculat- ed value of 3.40 g/cm3 based on the measured composition.The luster of fracture surfacescould not be accurately observed, but the luster of the prism faces is vitreous. Petersiteis readily soluble in 1:1 hydrochloric acid, coloring the solution light greenishyellow. Optically,petersite is uniaxial (+) with indicesof refraction e : 1.747(4)and r,,l : 1.666(4).The birefringenceis similar to that of other membersof the mixite group. Pleochroismis strong, E > O, with E : green,O : light yellowishgreen. Calcula- tion of the Gladstone-Dalerelationship, using the constantsof Mandarino (1976)yields Kc : 0.191 andKp : 0.203,providing good agreementbetween Fig. 2. Scanning electron microscope photomicrograph physicaland chemicaldata. There is no discernible showing semispherulesof tightly packed petersite crystals. fluorescenceunder ultraviolet radiation. PEACOR AND DUNN: PETERSITE lMl Chemistry group, and having rare earth elements dominant Petersitewas chemically analyzedusing an ARL- over Ca. snuq electron microprobe utilizing an operating The substitutionof Ca2* in a site occupiedprinci- voltageof 15kV and a samplecurrent of 0.025pA, pally by cations having a charge of +3 requires standardizedon brass. The standardsused were somediscussion, as the charge-balanced,end-mem- synthetic olivenite (Cu), fluorapatite (P), horn- ber formularequires that no cationsof charge*2 be blende(Fe, Ca), and the Drake rare earth glasses in that site.The mutual solid solutionof Ca for REE for REE. The data were correctedusing a modified occurs in many phases.However, it requires cou- versionof the uecrc-4 programof the Geophysical pling with some other substitution mechanismin Laboratory. The resultant analysis yields: P2O5 order to maintain charge balance. One possible ---> 23.1,CuO 52.1, CaO 2.4,FeO 0.8, Y2O3 2.5, Ce2O3 substitutionis 3Ca2* 2M3+ * n. However, the 2.5,Nd2O3 1.2, Sm2O3 1.2,La2O31.0 with HzO 12.3 crystal structureof mixite and isostructuralphases weightpercent by difference,sum : 100.0percent. is not known, so we cannot hypothesizethe exis- (Pr,Gd, Eu, Tm, Ho werepresent as traces; Pb, Sr, tence of a site for such an addition solid solution Er, Dy, Ba, Yb and S were soughtbut not found). mechanism.There is some indication of such a The accuracyof the data is estimatedto be t 3Voof mechanismin that there is a slight excess(0.15) of the amount presentfor Ca, Fe, Cu and P; -+7Vaof Y, REE, Fe and Ca over the value of 2.0 per unit the amount present for REE. Fe was assignedto cell. A second possible substitution mechanism Fe2* on the basisof a microchemicaltest. The unit couldbe Ca2* + ! (or HzO)- M3* (OH)t-. There cell contentsfor petersite,calculated on the basisof is also some indication for this mechanismin the P:6atoms,are: observeddeficiency (0.4) of OH relativeto the ideal structure,coupled with an excessof H2O. The two Ys.a1Ce6. 2sNde.3 Sm6. 13lae. 1 1 Fefr j6Cas n)>2.I s postulated substitution mechanisms account for Cu12.s7(POa)o.oo(OH) r | 60'6.78H2Omuch of the Caz+ and Fe2*. However, such inter- pretationsare beyond the limits of the precisionof or, ideally, (Y,REE,Ca)zCurz(POa)6(OH)r2.6H2Othe available chemical data. Definition of the actual with the sum of REE > Ca and with Y as the substitutionmechanisms requires additional analyt- dominant rare earth. A wavelength-dispersivemi- ical data on other phases,preferably those with a croprobe scan indicated the absenceof any other highercontent of calcium. elementswith atomic numbergreater than 9 includ- Occurrence ing Al, As and Bi, elementsfound in other members of the mixite group. There is too little materialfor Petersitewas found by Mr. Nicholas Facciollain the direct determinationof water.
Load more

Recommended publications
  • Mixite Bicu6(Aso4)3(OH)6 • 3H2O C 2001-2005 Mineral Data Publishing, Version 1 Crystal Data: Hexagonal
    Mixite BiCu6(AsO4)3(OH)6 • 3H2O c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Hexagonal. Point Group: 6/m. As acicular crystals, elongated along [0001], commonly in mats, radial fibrous aggregates, or cross-fiber veinlets. Physical Properties: Hardness = 3–4 D(meas.) = 3.79–3.83 D(calc.) = [4.04] Optical Properties: Transparent to translucent. Color: Blue-green to emerald-green, pale green, white; pale green to colorless in transmitted light. Streak: Pale bluish green. Luster: Vitreous, silky in aggregates. Optical Class: Uniaxial (+). Pleochroism: O = colorless; E = bright green. Absorption: E > O. ω = 1.743–1.749 = 1.810–1.830 Cell Data: Space Group: P 63/m. a = 13.646(2) c = 5.920(1) Z = 2 X-ray Powder Pattern: Anton mine, Germany. 12.03 (10), 2.46 (9), 3.57 (8), 2.95 (7), 2.86 (6), 2.70 (6), 2.57 (6) Chemistry: (1) (2) (3) P2O5 1.05 0.06 As2O5 29.51 28.79 29.64 SiO2 0.42 Fe2O3 0.97 Bi2O3 12.25 11.18 20.03 FeO 1.52 CuO 44.23 43.89 41.04 ZnO 2.70 CaO 0.83 0.26 H2O 11.06 11.04 9.29 Total 100.45 99.31 100.00 • (1) J´achymov, Czech Republic. (2) Tintic district, Utah, USA. (3) BiCu6(AsO4)3(OH)6 3H2O. Mineral Group: Mixite group. Occurrence: An uncommon secondary mineral in the oxidized zone of copper deposits. Association: Bismutite, smaltite, bismuth, atelestite, erythrite, malachite, barite. Distribution: From the Geister vein, Werner mine, J´achymov (Joachimsthal), Czech Republic.
    [Show full text]
  • 02-Newsl7tabs 27..32
    Mineralogical Magazine, February 2011, Vol. 75(1), pp. 27À31 CNMNC Newsletter IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) NEWSLETTER 7 New minerals and nomenclature modifications approved in 2010 1 2 3 P. A. WILLIAMS (Chairman, CNMNC), F. HATERT (Vice-Chairman, CNMNC), M. PASERO (Vice-Chairman, 4 CNMNC) AND S. J. MILLS (Secretary, CNMNC) 1 School of Natural Sciences, University of Western Sydney, Locked Bag 1797, Penrith South DC, NSW 1797, Australia À [email protected] 2 Laboratoire de Mine´ralogie, Universite´ de Lie`ge, B-4000 Lie`ge, Belgium À [email protected] 3 Dipartimento di Scienze della Terra, Universita` degli Studi di Pisa, Via Santa Maria 53, I-56126 Pisa, Italy À [email protected] 4 Department of Earth and Ocean Sciences, University of British Columbia, Vancouver BC, Canada V6T 1Z4 À [email protected] The information given here is provided by the IMA Commission on New Minerals, Nomenclature and Classification for comparative purposes and as a service to mineralogists working on new species. Each mineral is described in the following format: NEW MINERAL PROPOSALS APPROVED IN NOVEMBER 2 010 Mineral name, if the authors agree on its IMA No. 2010-044 release prior to the full description appearing Titanium in press Ti Chemical formula Orebody 31, Luobusa mining district, in Qusong Type locality County, Tibet (29º5’N 92º5’E) Full authorship of proposal Fang Qing-Song, Shi Ni-Cheng, Li Guo-Wu*, E-mail address of corresponding author Bai Wen-Ji, Yang Jing-Sui, Xiong Ming, Rong Relationship to other
    [Show full text]
  • Agardite-(Y), Cu 6Y(Aso4)3(OH)6Á3H2O a = 13.5059 (5) a T = 293 K C = 5.8903 (2) A˚ 0.10 Â 0.02 Â 0.02 Mm
    inorganic compounds Acta Crystallographica Section E Experimental Structure Reports Crystal data Online ˚ 3 Cu5.70(Y0.69Ca0.31)[(As0.83P0.17)O4]3- V = 930.50 (6) A ISSN 1600-5368 (OH)6Á3H2O Z =2 Mr = 985.85 Mo K radiation À1 Hexagonal, P63=m = 13.13 mm 2+ ˚ Agardite-(Y), Cu 6Y(AsO4)3(OH)6Á3H2O a = 13.5059 (5) A T = 293 K c = 5.8903 (2) A˚ 0.10 Â 0.02 Â 0.02 mm a b Shaunna M. Morrison, * Kenneth J. Domanik, Marcus J. Data collection a a Origlieri and Robert T. Downs Bruker APEXII CCD 20461 measured reflections diffractometer 786 independent reflections aDepartment of Geosciences, University of Arizona, 1040 E. 4th Street, Tucson, Absorption correction: multi-scan 674 reflections with I >2(I) Arizona 85721-0077, USA, and bLunar and Planetary Laboratory, University of (SADABS; Bruker, 2004) Rint = 0.048 Arizona, 1629 E. University Blvd., Tucson, AZ. 85721-0092, USA Tmin = 0.353, Tmax = 0.779 Correspondence e-mail: [email protected] Refinement Received 24 July 2013; accepted 21 August 2013 R[F 2 >2(F 2)] = 0.032 1 restraint wR(F 2) = 0.086 H-atom parameters not refined ˚ À3 Key indicators: single-crystal X-ray study; T = 293 K; mean () = 0.000 A˚; H-atom S = 1.14 Ámax = 2.34 e A ˚ À3 completeness 0%; disorder in main residue; R factor = 0.032; wR factor = 0.086; 786 reflections Ámin = À0.79 e A data-to-parameter ratio = 13.1. 60 parameters 2+ Agardite-(Y), with a refined formula of Cu 5.70(Y0.69Ca0.31)- Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT 2+ [(As0.83P0.17)O4]3(OH)6Á3H2O [ideally Cu 6Y(AsO4)3(OH)6Á- (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine 3H2O, hexacopper(II) yttrium tris(arsenate) hexahydroxide trihydrate], belongs to the mixite mineral group which is structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Xtal- characterized by the general formula Cu2+ A(TO ) (OH) Á- Draw (Downs & Hall-Wallace, 2003); software used to prepare 6 4 3 6 material for publication: publCIF (Westrip, 2010).
    [Show full text]
  • A Specific Gravity Index for Minerats
    A SPECIFICGRAVITY INDEX FOR MINERATS c. A. MURSKyI ern R. M. THOMPSON, Un'fuersityof Bri.ti,sh Col,umb,in,Voncouver, Canad,a This work was undertaken in order to provide a practical, and as far as possible,a complete list of specific gravities of minerals. An accurate speciflc cravity determination can usually be made quickly and this information when combined with other physical properties commonly leads to rapid mineral identification. Early complete but now outdated specific gravity lists are those of Miers given in his mineralogy textbook (1902),and Spencer(M,i,n. Mag.,2!, pp. 382-865,I}ZZ). A more recent list by Hurlbut (Dana's Manuatr of M,i,neral,ogy,LgE2) is incomplete and others are limited to rock forming minerals,Trdger (Tabel,l,enntr-optischen Best'i,mmungd,er geste,i,nsb.ildend,en M,ineral,e, 1952) and Morey (Encycto- ped,iaof Cherni,cal,Technol,ogy, Vol. 12, 19b4). In his mineral identification tables, smith (rd,entifi,cati,onand. qual,itatioe cherai,cal,anal,ys'i,s of mineral,s,second edition, New york, 19bB) groups minerals on the basis of specificgravity but in each of the twelve groups the minerals are listed in order of decreasinghardness. The present work should not be regarded as an index of all known minerals as the specificgravities of many minerals are unknown or known only approximately and are omitted from the current list. The list, in order of increasing specific gravity, includes all minerals without regard to other physical properties or to chemical composition. The designation I or II after the name indicates that the mineral falls in the classesof minerals describedin Dana Systemof M'ineralogyEdition 7, volume I (Native elements, sulphides, oxides, etc.) or II (Halides, carbonates, etc.) (L944 and 1951).
    [Show full text]
  • Occurrence and Crystal Structure of Calciopetersite from Monte Beni (Firenzuola, Florence, Tuscany, Italy)
    Atti Soc. tosc. Sci. nat., Mem., Serie A, 116 (2011) pagg. 17-22, figg. 2, tabb. 4; doi: 10.2424/ASTSN.M.2011.03 C. Biagioni (*), E. Bonaccorsi (*), P. Orlandi (*) OCCURRENCE AND CRystal structure OF CALCIOPETERSITE from MONTE BENI (FIRENzUOLA, FLORENCE, TUSCANy, Italy) Abstract - The mixite group includes several hexagonal Introduction phosphates and arsenates, characterized by the general chem- ical formula MCu6(XO4)3(OH)6⋅3H2O. A phosphate belong- The mixite group is formed by a series of hexagonal ing to this group has been identified on samples collected at phosphates and arsenates, having the general chemical the Fantoni quarry (Monte Beni, Firenzuola, Florence), as formula MCu6(XO4)3(OH)6⋅3H2O. M is represented by tufts of acicular crystals with hexagonal section, blue-green 3+ 3+ 3+ 3+ 2+ 2+ 5+ 5+ in color, associated with chrysocolla. Semi-quantitative REE , y , Al , Bi , Ca , or Pb ; X can be As or P . chemical data point to a dominance of Ca over y, indicat- Up to now, only two natural phosphates have been ing that these samples could be classified as calciopetersite. described: petersite-(y) and calciopetersite. Petersite- The crystal structure of this mineral has been solved and (y), ideally yCu6(PO4)3(OH)6⋅3H2O, was described refined using intensity data collected through synchrotron by Peacor & Dunn (1982) and was found in very radiation, due to the extremely small size of the single crys- few localities world-wide; calciopetersite, ideally tals. Calciopetersite is hexagonal, space group P6 /m, cell 3 CaCu6(PO4)2(PO3OH)(OH)6⋅3H2O, is rarer than the parameters a 13.206(2), c 5.824(3) Å.
    [Show full text]
  • Analyses of Rocks and Minerals
    DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, DIRECTOR BULLETIN 419 ANALYSES OF ROCKS AND MINERALS FEOM THE LABORATORY OF THE UNITED STATES GEOLOGICAL SURVEY \ 1880 TO 1908 TABULATED BY F. W. CLARKE, CHIEF CHEMIST WASHINGTON GOVERNMENT PRINTING OFFICE 1910 CONTENTS. Page. Introduction.............................................................. 1 The average composition of rocks. ..'.....< .................................. 4 Analyses of igneous and crystalline rocks................................... 13 Maine. .................................................................... 13 1. Rocks from Aroostook County..... ^..................'........... 13 2. Miscellaneous rocks............................................. 14 New Hampshire....................................................... 15 Vermont............................................................... 15 1. Rocks of Mount Ascutney........................................ 15 2. Miscellaneous rocks.................:........................... 17 Massachusetts....:..............................................:..... .18 1. Magnesian rocks.............. ; .................................. 18 2. Amphibolite................................................... 19 3. Miscellaneous rocks............................................. 21 Connecticut............................................................ 24 New York............................................................. 26 1. Rocks of the Adirondack region................................... 26 2.
    [Show full text]
  • OCCURRENCE and GENESIS of RARE ARSENATE and PHOSPHATE MINERALS AROUND PIZZO CERVANDONE, ITALY Jswitzerland
    Soc. ItClli4n(l dl Mlntl'ClIOglCl .. PdrolOglCl • RIINDrCONTr. Vol. xxxrr (1), /976 : n . 219-211 S1'EfAN GRAESEJI.·, ALDO G. ROCCIA NI ·· OCCURRENCE AND GENESIS OF RARE ARSENATE AND PHOSPHATE MINERALS AROUND PIZZO CERVANDONE, ITALY jSWITZERLAND ABSTIlACf. _ Physica: and X.ray data from a Dumber of rare minerals (mostly arsenates) such as aUacsiu:, asbecasite, and chemovite, from the region around the Pizw Cervandone on the Swiss-Italian border, are presented. 1be genesis of these minerals, many of which have not been previously described from Italian territory, is explained as the result of the .. remobilisation,. of an old (Hercynian ) Cu·As-ore deposit in the center of the area. Such a remobilisation process has been previously postulated to account for the occurrence of SUlphosalt minerals (Pb-Cu-Ag.As sulphides) in the dolomitie rocks al Binntal to the north of the region (in particular al Lengenbach ). Alllhe minerals described in Ihis paper are new to Ilalian territory. RIASSUNTO. - In queslO lavow descriviamo una regione anomo al Piuo Cerv&ndone, sui confine italo-svizzero, tra Binntal (5vizztt1l) e la Val Devero (Italia). Questa regione ~ diventata nota dopo il ritrovamento di una serie di minerali rari e, a volte, unici (in prevalenza arseniati) come la Cafarsile, l'Asbea.site, la Chernovite, il ClorotibMixite, eec. di cui vengono riportati i dad fisici e quelli risultanti dall'esame ai raggi X, eec. Tali minerali (compteso il Nb-Rutilo) rappresemano, tulti, specie nuove per il territorio it& liaoo. La genesi di questi minerali ~ spiegala come conseguenza dei processi di rimozione di un amico (Erciniaoo) deposito minerale di eu·As esiSlente nel cenlro deUa zona.
    [Show full text]
  • PETERSITE-(Ce), CU 6Ce(PO4)3(OH)63H2O, a NEW MIXITE GROUP MINERAL from YAVAPAI COUNTY, ARIZONA, USA
    1505 The Canadian Mineralogist Vol. 54, pp. 1505-1511 (2016) DOI: 10.3749/canmin.1500050 2þ PETERSITE-(Ce), CU 6Ce(PO4)3(OH)6Á3H2O, A NEW MIXITE GROUP MINERAL FROM YAVAPAI COUNTY, ARIZONA, USA § SHAUNNA M. MORRISON ,KENNETH J. DOMANIK, HEXIONG YANG, AND ROBERT T. DOWNS Department of Geosciences, University of Arizona, 1040 E 4th Street, Tucson, Arizona 85721-0077, USA ABSTRACT 2þ A new mineral, petersite-(Ce), ideally Cu 6Ce(PO4)3(OH)6Á3H2O (IMA2014-002), has been found in the Cherry Creek District of Yavapai County, Arizona, USA. It is a secondary alteration mineral associated with malachite, chlorite, a biotite phase, quartz, albite, orthoclase, hematite, chalcopyrite, and an uncharacterized hisingerite-like mineral. Petersite-(Ce) occurs as sprays of yellowish-green, acicular crystals approximately 20 3 20 3 50 lm in size. It has a white streak with vitreous luster. The mineral is brittle and has a Mohs hardness of ~3.5; no cleavage or parting was observed. The calculated density is 3.424 g/ 3 cm . An electron microprobe analysis resulted in an empirical chemical formula of Cu6.05(Ce0.18Y0.16La0.12Nd0.09Gd0.03Pr0.02 Dy0.01Sm0.01Ca0.42)R1.04[(PO4)2.54(SiO4)0.14(PO3OH)0.32(OH)6]Á3.65H2O. ˚ ˚ Petersite-(Ce) is hexagonal, with space group P63/m and unit-cell parameters a 13.2197(18) A, c 5.8591(9) A, and V 886.8(4) A˚ 3, Z ¼ 2. It is the Ce analogue of petersite-(Y) and exhibits the mixite structure type. The mixite group can be 2þ expressed by the general formula Cu 6A(TO4)3(OH)6Á3H2O, where nine-coordinated A is a rare earth element, Al, Ca, Pb, or Bi, and T is P or As.
    [Show full text]
  • Diverse Employees Are Struggling the Most During COVID-19—Here's How Companies Can Respond
    Diverse employees are struggling the most during COVID-19—here’s how companies can respond New global research shows that despite companies’ recent efforts, diverse employees need more. Businesses should ask themselves new questions for a changed workplace. This article was a collaborative effort by Kweilin Ellingrud, Mekala Krishnan, Alexis Krivkovich, Kathryn Kukla, Ana Mendy, Nicole Robinson, Sandra Sancier-Sultan, and Lareina Yee. © Jules_Kitano/Getty Images November 2020 Almost a year into the COVID-19 crisis, employees heightened loss of connectivity and belonging. are still crying out for more support. Diverse This may contribute to the fact that LGBTQ+ groups—including women, LGBTQ+ employees, employees are more likely to report challenges people of color, but also working parents—are with mental-health issues. having the hardest time, both in the workplace and with balancing work and home life. In majority-white countries, people of color (POC) are especially worried about workplace health and To understand the challenges diverse employees safety, as well as career progression and balancing are grappling with in the COVID-19 environment, responsibilities at home. The disparity compared we recently conducted surveys and interviews and with their white counterparts is particularly stark for examined data across 11 developed and developing POC in the United States. countries (see sidebar, “Our survey methodology”).1 We discovered that workers across demographic What do these results mean for companies? We groups and geographies reported a remarkably find that employers are well aware of the challenges similar set of challenges related to mental health, facing employees, and that nearly all companies work–life balance, workplace health and safety, a have implemented COVID-19-specific policies and missing sense of connectivity and belonging with programming to support workforces during this colleagues, and concerns about job opportunities.
    [Show full text]
  • AFMS Mineral List 2003
    American Federation Of Mineralogical Societies AFMS Mineral Classification List New Edition Updated for 2003 AFMS Publications Committee B. Jay Bowman, Chair 1 Internet version of Mineral Classification List. This document may only be downloaded at: http://www.amfed.org/rules/ Introduction to the Mineral Classification List The AFMS Rules Committee voted to eliminate the listing in the Rulebook of references for mineral names except for the AFMS Mineral Classification List. Exhibitors are encouraged to use the AFMS List when exhibiting in the B Division (Minerals). If the mineral they are exhibiting is not on the AFMS List they should note on the Mineral list they present to the judging chairman which reference they did use for the information on their label. The Regional Rules Chairs have been asked to submit names to be added to the list which will be updated with addendum’s each year. In a few years the list should represent most of the minerals generally exhibited out of the 4200+ now recognized by the IMA. This list follows the Glossary of Mineral species which is the IMA approved names for minerals. When the Official name of the mineral includes diacritical mark, they are underlined to indicate they are the IMA approved name. Where usage of old names has been in use for years they have been included, but with the approved spelling underlined following it. The older spelling will be accepted for the present so exhibitors will not have to correct there present label. This list may not contain all mineral species being exhibited. Exhibitors are encouraged to submit names to be added to the list to the Rules committee.
    [Show full text]
  • Women on Boards: Sharing a Rigorous Vision of the Functioning of Boards, Demanding a New Model of Corporate Governance
    Journal of Research in Gender Studies Volume 4(1), 2014, pp. 101–140, ISSN: 2164-0262 Women on Boards: Sharing a Rigorous Vision of the Functioning of Boards, Demanding a New Model of Corporate Governance VIVIANE DE BEAUFORT [email protected] ESSEC Business School LUCY SUMMERS [email protected] University of Queensland ABSTRACT. This study offers Executives and Policy Makers a thorough analysis of the most current data from international organizations and consulting firms, as well empirical evidence from interviews of women 50 executive women who hold mandates on Boards around the globe, on the increasing economic importance of greater gender diversity on Boards. A discussion of the various feasible “strategies” currently being proposed and adopted by different countries and other concerned parties and organizations to increase female Board representation suggests that progress is in sight, but that there are many obstacles to be remedied if women are to be a real engine for a more effective Corporate Governance of Boards. The study provides empirical support that women must be encouraged to bring, in terms of skills and behaviors, a difference to the table if “gender diversity” measures are to have positive and genuine change in the exercise of effective Corporate Governance practices internationally. The study highlights that current and potential female candidates share a rigorous vision of the functioning of Boards and therefore demand a new model of governance based on sustainability, which integrates both masculine and feminine “polarities” within companies and organizations. Keywords: International Corporate Governance; Board Diversification; evolution of models of governance; women and boards; non-executive board members; gender dimension RESEARCH QUESTION/ISSUE: The study first seeks to better understand and classify the “added value” effects and economic implications that may plausibly result from a significant push towards increased gender diversity on Boards.
    [Show full text]
  • Unusual Pigments Found in a Painting by Giotto (C
    Berrie et al. Herit Sci (2016) 4:1 DOI 10.1186/s40494-016-0070-9 RESEARCH ARTICLE Open Access Unusual pigments found in a painting by Giotto (c. 1266‑1337) reveal diversity of materials used by medieval artists Barbara H. Berrie1*, Marco Leona2 and Richard McLaughlin3 Abstract Background: The important trecento Florentine artist Giotto (c. 1266-1337) is renowned for his naturalistic and real- istic works in tempera and fresco. His innovative paintng style involved painting expressive, emotive faces and use of pictorial devices for depicting space. This report focuses on the analysis of the materials and methods used in a panel in the collection of the National Gallery of Art, Madonna and Child (1310/1315). Results: Giotto used inky washes under thin layers of egg tempera paint. Yellow iron earth and lead tin yellow are present in the paint used to depict the lining of the Virgin’s mantle. SEM-EDX of one of the yellow pigments confirmed it is lead tin yellow type II, PbSn1-xSixO3. The ratio of colorant to the glassy phase indicates this material was produced for use as a pigment rather than as a glass. Ultramarine was not used in this painting, azurite is the blue pigment. The azurite used here does not contain elemental impurities, however malachite and the rare green–blue mineral mixite, BiCu6(OH)6(AsO4)3(H2O)3, are found in the blue paint. Keywords: Giotto di Bordone, Mixite, Lead tin yellow type II, Raman, EBSD, Copper arsenates Background which might have been part of the same altarpiece [1]. The important trecento Florentine artist Giotto di Bor- Giotto used techniques similar to those described for done (c.
    [Show full text]