Correianevesite, Fe2+Mn22+(PO4)2·3H2O, a new reddingite-group … · 2014. 4. 9. · The...

$: Correianevesite, Fe2+Mn22+(PO4)2·3H2O, a new reddingite-group … · 2014. 4. 9. · The Gladstone-Dale compatibility between chemical data, refractive indices and density is (1$
Correianevesite Fe2+Mn22+(PO4)2middot3H2O a new reddingite-group mineral from the Cigana

mine Conselheiro Pena Minas Gerais Brazil

Nikita V ChukaNoV1 RiCaRdo SCholz2 Natalia V zubkoVa3 igoR V PekoV3 dmitRiy i belakoVSkiy4 koNStaNtiN V VaN5 leoNaRdo lagoeiRo2 leoNaRdo m gRaccedila2

klauS kRambRoCk6 luiz Ca de oliVeiRa7 luiz ad meNezeS Filho8 maacuteRio lSC ChaVeS8 aNd dmitRiy y PuShChaRoVSky3

1Institute of Problems of Chemical Physics Russian Academy of Sciences Chernogolovka Moscow Region 142432 Russia2Escola de Minas Departamento de Geologia Universidade Federal de Ouro Preto (UFOP) Campus Morro do Cruzeiro 35400-000

Ouro Preto Minas Gerais Brazil3Faculty of Geology Moscow State University Vorobievy Gory Moscow 119991 Russia

4Fersman Mineralogical Museum Russian Academy of Sciences Leninskiy Prospekt 18-2 Moscow 119071 Russia5Institute of Experimental Mineralogy Russian Academy of Sciences Chernogolovka Moscow Region 142432 Russia

6Departamento de Fiacutesica Instituto de Ciecircncias Exatas Universidade Federal de Minas Gerais Avenida Antocircnio Carlos 6627 31270-901 Belo Horizonte Minas Gerais Brazil

7Departamento de Quiacutemica Instituto de Ciecircncias Exatas Universidade Federal de Minas Gerais Avenida Antocircnio Carlos 6627 31270-901 Belo Horizonte Minas Gerais Brazil

8Departamento de Geologia Instituto de Geociecircncias Universidade Federal de Minas Gerais Avenida Antocircnio Carlos 6627 31270-901 Belo Horizonte Minas Gerais Brazil

abStRaCt

Correianevesite ideally Fe2+Mn22+(PO4)2middot3H2O is a new reddingite-group mineral approved by

the CNMNC (IMA 2013-007) It occurs in a phosphate-rich granite pegmatite that outcrops near the Cigana mine Conselheiro Pena Rio Doce valley Minas Gerais Brazil Associated minerals are triphylite lithiophilite frondelite rockbridgeite eosphorite vivianite fairfieldite leucophosphite cyrilovite phosphosiderite etc Correianevesite occurs as grayish-brown to reddish-brown transparent bipyramidal crystals up to 4 mm in size The streak is white and the luster is vitreous Mohs hardness is 3frac12 Cleavage is poor on (010) Fracture is laminated uneven across cleavage The measured den-sity is 325(2) gcm3 the calculated density is 3275 gcm3 The mineral is biaxial (+) α = 1661(5) β = 1673(5) γ = 1703(5) 2Vmeas = 70(10)deg 2Vcalc = 656deg The IR spectrum confirms the presence of H2O The Moumlssbauer spectrum shows the presence of two sites for Fe2+ and one site for Fe3+ occupied in the ratio Fe12+Fe22+Fe3+ = 39556 The chemical composition is as follows (electron microprobe H2O determined by gas chromatography of ignition products Fe apportioned between FeO and Fe2O3 based on Moumlssbauer data wt) MnO 2921 FeO 2174 Fe2O3 154 P2O5 3459 H2O 126 total 9968 The empirical formula based on 11 O apfu is H578Mn170Fe2+

125Fe3+008P2015O11 The strongest lines of the

powder X-ray diffraction pattern [d Aring (I ) (hkl)] are 508 (43) (020) 4314 (28) (002 210) 3220 (100) (221 202) 3125 (25) (122) 2756 (35) (103 230) 2686 (25) (222 113) 2436 (22) (123) and 2233 (23) (411 331) The crystal structure is solved (R1 = 00176) Correianevesite is orthorhombic space group Pbna a = 94887(2) b = 101149(2) c = 87062(2) Aring V = 83560(3) Aring3 Z = 4 The refined crystal-chemical formula is (Fe2+

072Mn2+020Fe3+

008)(Mn148Fe2+052)(PO4)2 (H2OOH)3

Keywords Correianevesite new mineral phosphate reddingite group Cigana mine Conselheiro Pena Rio Doce valley Minas Gerais Brazil crystal structure Moumlssbauer spectroscopy

iNtRoduCtioN

Correianevesite is a new mineral approved by the IMA Com-mission on New Minerals Nomenclature and Classification (IMA no 2013-007) It was discovered in a granite pegmatite outcropped by the Cigana mine (Lavra da Cigana formerly known as Jocatildeo mine) Rio Doce valley Conselheiro Pena county Minas Gerais Brazil The pegmatite belongs to the Conselheiro Pena pegmatite district Eastern Brazilian pegmatite province known for a wide

diversity of phosphate minerals (Pedrosa-Soares et al 2011)The Cigana pegmatite is mined out and in the past was mined

for industrial feldspar and with minor importance gemstones and samples for the collectors market The pegmatite is heterogeneous with well-developed mineralogical and textural zoning It has sym-metric lens shape with the longer axis trending to NW-SE and the body dipping subvertically The extension is at least 50 m and the thickness is up to 20 m The pegmatite is hosted by quartz-mica schist with garnet staurolite and sillimanite of the Satildeo Tomeacute Formation Hydrothermal and metasomatic fluids were respon-sible for the albitization the development of miarolitic cavities

American Mineralogist Volume 99 pages 811ndash816 2014

0003-004X140004ndash811$0500DOI httpdxdoiorg102138am20144709 811

E-mail chukanovicpacru

CHUKANOV ET AL CORREIANEVESITE A NEW REDDINGITE-GROUP MINERAL812

FiguRe 1 Bipyramidal crystals of correianevesite on hureaulite Field of view 6 mm Photo Carlos Menezes

and the formation of a complex secondary phosphate assemblage described by Chaves et al (2005)

The primary mineral association is represented by quartz muscovite microcline schorl almandine-spessartine spodumene and triphylite The secondary association is mainly composed by albite Ta and Nb oxides hydrothermal beryl cassiterite pyrite and numerous phosphates formed as a result of alteration of triphylite (Chaves et al 2005) The paragenetic assemblage of secondary phosphates is composed by lithiophillite correia-nevesite hureaulite frondelite fluorapatite eosphorite fairfieldite gormanite and vivianite

The new mineral is named in memory of Joseacute Marques Correia Neves (1929ndash2011) professor of the Instituto de Geociecircncias Universidade Federal de Minas Gerais who was the most active geoscientist in the study of Brazilian pegmatites especially in the region of Conselheiro Pena and Araccediluai as well as in Alto Ligonha in Mozambique where he discovered hafnon the Hf analog of zircon

The type specimen of correianevesite (a part of the holotype) is deposited in the mineralogical collections of the Museu de Ciecircncia e Teacutecnica Escola de Minas Universidade Federal de Ouro Preto Praccedila Tiradentes Centro 35400-000 ndash Ouro Preto MG Brazil with the registration number SAA-081B

geNeRal aPPeaRaNCe aNd PhySiCal PRoPeRtieS

Correianevesite occurs as light grayish-brown to reddish-brown transparent bipyramidal crystals up to 4 mm in size (Fig 1) in cavities of triphylite The only form observed is 111 The streak is white and the luster is vitreous The mineral is non-fluorescent under ultraviolet light Mohs hardness is 3frac12 Cleavage is poor on (010) Fracture is laminated uneven across cleavage The density measured by flotation in heavy liquids is 325(2) gcm3 The calculated density is 3275 gcm3 based on the empirical formula and unit-cell parameters obtained from the single-crystal X-ray diffraction data

Thermal data for correianevesite were obtained using a Shi-madzu analyzer in a nitrogen atmosphere at a gas flow rate of 50 cm3 minndash1 Differential thermal analysis (DTA) and thermogravi-metric (TG) analyses were carried out simultaneously Crushed samples with 1488 mg weight were heated in an open platinum

crucible at a rate of 10 degC minndash1 up to a temperature of 800 degC The TG curve of correianevesite in nitrogen atmosphere is given in Figure 2

The lowered weight loss of 1045 obtained by TG as compared with H2O content of 126 wt obtained by gas chro-matography of products of ignition (see below) is explained by self-oxidation (a phenomenon typical of Fe2+- and Mn2+-phosphates see eg Frost et al 2004 Chukanov et al 2012) in accordance with the following simplified schemes (M = Fe Mn)

2M2+ + H2O rarr 2M3+ + O2ndash + H2

2M2+ + 2H2O rarr 2M3+ + 2OHndash + H2

These processes correspond to exothermic effects in the DTA curve (Fig 3) and may be explained by the partial oxidation of Fe2+ to Fe3+

To obtain infrared (IR) absorption spectrum correianevesite powder was mixed with anhydrous KBr pelletized and analyzed using an ALPHA FTIR spectrometer (Bruker Optics) at the resolu-tion of 4 cmndash1 and number of scans of 16 IR spectrum of analogous pellet of pure KBr was used as a reference

Absorption bands in the IR spectrum of correianevesite (Fig 4) and their assignments are (cmndash1 s = strong band w = weak band sh = shoulder) 3457 3200 (O-H stretching vibrations of H2O molecules and OH anions hydrogen bonds of medium strengths) 2530 2033w 1890 (vibrations of the fragments O-HhellipO-P very strong hydrogen bonds of acidic OH groups) 2247w (overtone of asymmetric stretching vibrations of PO4

3ndash anions) 1636w 1575 (bending vibrations of H2O molecules) 1054s 1013s (asymmetric stretching vibrations of PO4

3ndash anions) 758 750sh 661 (librational vibrations of H2O molecules forming strong hydrogen bonds) 598 570 555sh (O-P-O bending vibrations of PO4

3ndash anions) 476w 417w 384w (mixed lattice vibrations)

Bands of B- C- and N-bearing groups are absent in the IR spectrum of correianevesite The nature of anomalously strong hydrogen bonds is discussed below

The IR spectrum of correianevesite is comparable to those of the isostructural minerals phosphoferrite and reddingite

Moumlssbauer spectra were collected in constant acceleration

FiguRe 2 TG curve of correianevesite obtained in nitrogen atmosphere at a heating rate of 10 degC minndash1

CHUKANOV ET AL CORREIANEVESITE A NEW REDDINGITE-GROUP MINERAL 813

FiguRe 4 IR spectrum of powdered correianevesite in KBr pellet

probe of 20 kV and a beam current of 05 nA The beam was rasterized on an area 16 times 16 μm to minimize unstable sample damage Attempts to use WDS mode with higher beam current were unsuccessful because of the instability of the mineral con-taining water The contents of F Na Mg Al Si S K Ca Ti Zn and As are below their detection limits H2O was analyzed by gas chromatography of products of ignition at 1200 degC CO2 was not analyzed because of the absence of absorption bands correspond-ing to vibrations of C-O bonds in the IR spectrum Analytical data are given in Table 2

The empirical formula based on 11 O atoms is H578Mn170

Fe2+125Fe3+

008P2015O11The simplified formula is Fe2+Mn2+2 (PO4)2middot3H2O

which requires MnO 3463 FeO 1754 P2O5 3464 H2O 1319 total 10000 wt

The Gladstone-Dale compatibility between chemical data refractive indices and density is (1 ndash KPKC) = 0013 (superior)

X-Ray diFFRaCtioN data aNd CRyStal StRuCtuRe

The X-ray powder-diffraction data (Table 3) were collected with a STOE IPDS II single-crystal diffractometer equipped with an Image Plate detector using the Gandolfi method by employ-ing the MoKα radiation and a samplendashdetector distance of 200 mm Orthorhombic unit-cell parameters refined from the powder data are as follows a = 9491(7) b = 10121(7) c = 8721(9) Aring V = 838(2) Aring3 Measured interplanar spacings and intensities of

FiguRe 3 DTA curve of correianevesite obtained in nitrogen atmosphere at a heating rate of 10 degC minndash1

FiguRe 5 Moumlssbauer spectrum of correianevesite

Table 1 Moumlssbauer data for correianevesiteCation Isomer shift Quadrupole Line width Area mms splitting mms mms Fe12+ 123(4) 163(1) 027(2) 39(1)Fe22+ 123(4) 240(9) 029(1) 55(3)Fe3+ 035(1) 120(3) 049(5) 60(3)

Table 2 Chemical composition of correianevesiteConstituent Content wt Range Stdev Probe standardMnO 2921 2787ndash3014 078 MnTiO3

FeOa 2174 2209ndash2445b 077b Fe2O3

Fe2O3a 154

P2O5 3459 3419ndash3502 027 LaPO4

H2O 126 plusmn 01 Total 9968 a Total iron content analyzed using a microprobe and initially calculated as FeO was 2313 wt it was apportioned between FeO and Fe2O3 (as well as between two sites) based on Moumlssbauer data (see Authorsrsquo Remarks) b For total iron calculated as FeO

transmission mode with a 10 mCi 57CoRh source at 25 and 298 K The data were stored in a 1024-channel MCS memory unit and were fitted using Lorentzian line shapes with a least-squares fitting procedure using the NORMOS program Isomer shifts were calculated relatively to α-Fe

According to Moumlssbauer spectroscopy data (Fig 5 Table 1) correianevesite contains three kinds of iron cations (two bivalent and one trivalent) having sixfold coordination and present in the atomic proportions Fe12+Fe22+Fe3+ = 39556

Correianevesite is optically biaxial (+) α = 1661(5) β = 1673(5) γ = 1703(5) 2Vmeas = 70(10)deg 2Vcalc = 656deg Disper-sion of optical axes is strong r gt v The mineral is nonpleochroic colorless under the microscope

ChemiCal ComPoSitioN

Seven point analyses were carried out using using VEGA TS 5130MM SEM equipped with EDX analyzer [INCA Si(Li) detector] at an operating voltage of an electron micro-


observed reflections are in a good agreement with corresponding values calculated from the crystal structure

Single-crystal X-ray diffraction measurements were made with a single-crystal Xcalibur S diffractometer equipped with a CCD detector Absorption correction was applied according to the shape of the crystal The structure was solved by direct methods and refined anisotropically using SHELXS-97 and SHELXL-97 (Sheldrick 2008) respectively to R = 00176 for 1662 unique reflections with I gt 2σ(I) in space group Pbna All hydrogen atoms of two water molecules were found and refined (CIF1 available on deposit)

The structure model is in a good agreement with those of the other reddingite-group minerals A small amount of Mn was added to the Fe-dominant M(1) site and a small amount of Fe was added to the Mn-dominant M(2) site according to the results of the refinement of electronic composition of the site chemical and Moumlssbauer data The occupancy coefficients of the cations in M(1) and M(2) sites were fixed in the final stages of the refinement The crystallographic characteristics of the mineral the details of the X-ray diffraction study and the structure-refinement parameters are given in Table 4 atom coordinates and equivalent thermal displacement parameters in Table 5 anisotropic displacement pa-rameters in Table 6 and selected interatomic distances in Table 7

Like other representatives of the phosphoferrite structure type correianevesite contains (100) octahedral layers (Fig 6) formed by the parallel to the c axis chains of edge-sharing dimers of M(2)O4(H2O)2 polyhedra connected via common edges with isolated

Table 3 X-ray powder diffraction data for correianevesiteIobs dobs Aring Icalc a dcalc Aringb h k l3 645 2 6415 10119 544 20 5417 11143 508 45 5057 02021 4761 23 4744 20028 4314 4 27 4353 4295 002 2108 3985 8 3972 1214 3886 2 3852 21113 3471 17 3460 220100 3220 100 38 3216 3208 221 20225 3125 28 3116 12210 2985 5 8 2985 2973 131 30135 2756 15 38 2775 2748 103 23025 2686 12 29 2709 2676 222 1135 2567 5 1 2566 2563 132 32115 2484 10 20 2517 2481 023 31222 2436 29 2433 1238 2355 13 2353 14123 2233 16 19 2232 2230 411 33112 2184 12 4 2187 2177 042 00413 2136 3 16 2138 2131 303 1423 2087 2 1 2092 2085 313 4216 2040 1 9 2040 2038 412 33214 1973 2 18 1978 1970 204 32317 1933 1 11 1929 1926 151 3414 1855 7 1854 5015 1809 5 1806 3332 1767 4 1766 3143 1740 6 1741 5218 1712 6 4 1714 1713 512 1059 1649 7 6 5 1650 1646 1645 044 025 52215 1630 14 1630 1619 1588 2 2 13 1589 1588 1587 260 503 35213 1561 3 2 15 1563 1562 1558 261 610 24410 1520 3 16 1525 1516 305 4512 1491 2 1495 5411 1483 3 1487 6212 1467 1 4 1471 1466 612 3614 1452 3 7 1451 1448 006 4344 1423 1 6 1426 1420 622 1164 1419 1 1 1418 1416 145 5146 1381 4 4 1382 1380 270 1265 1340 1 1 7 1342 1341 1339 354 640 7012 1320 1 2 1319 1317 552 2722 1311 2 1310 4621 1299 2 1295 7213 1283 3 2 1283 1282 264 1732 1273 2 1 1279 1271 604 2551 1262 1 1264 0802 1242 3 1240 6242 1232 1 1228 3643 1210 1 2 1211 1210 562 2813 1206 4 1204 1822 1177 2 1176 2823 1170 3 1170 1563 1155 2 2 1153 1153 660 4554 1147 2 2 1151 1145 183 6531 1118 1 1116 8222 1107 1 4 1108 1105 147 743a For the calculated X-ray powder pattern only reflections with Icalc ge 1 are givenb Calculated for unit-cell parameters obtained from single-crystal data

Table 4 Crystal parameters data collection information and single-crystal structure refinement details for correianevesite

Formula (Fe02+

72Mn02+

20Fe03+

08)(Mn148Fe02+

52)(PO4)2[(H2O)292(OH)008]Formula weight 41001Crystal system space group Orthorhombic Pbna (no 60)Z 4a b c (Aring) 948871(16) 1011494(17) 870624(16)V (Aring3) 83561(3)F(000) 801Density ρcalc (gcm3) 3259(8)Absorption coefficient m (mmndash1) 5199Crystal dimensions (mm) 019 times 032 times 038Diffractometer Xcalibur S CCDλ (MoKα) (Aring) T (K) 071073 293Collection mode (full) sphereθ range for data collection(deg) 318ndash3494h k l ranges ndash15 le h le 15 ndash16 le k le 16 ndash13 le l le 13Reflections collected 20430Unique reflections 1781 (Rint = 00341)Reflections with I gt 2σ(I) 1662Structure solution direct methodsRefinement method full-matrix least-squares on F2

Weighting parameters a b 00174 03503Extinction coefficient 00047(4)No of refined parameters 90Final R indices [I gt 2σ(I)] R1 = 00176 wR2 = 00417R indices (all data) R1 = 00204 wR2 = 00430GoF 1134Δρmin Δρmax (eAring3) ndash031 042

Table 5 Site coordinates and thermal displacement parameters (Aring2) of atoms for correianevesite

Atom xa yb zc Ueq

M(1) = Fe080Mn020a 00 00 00 000978(6)

M(2) = Mn074Fe026a 0065331(19) 0097199(18) 063633(2) 001010(5)

P 020457(3) 010607(3) 029198(3) 000713(6)O(1) 021646(9) 025363(8) 033350(11) 001207(15)O(2) 010430(9) 003779(9) 040585(10) 001146(15)O(3) 035133(9) 004233(9) 030005(10) 001229(16)O(4) 014828(10) 009733(9) 012677(10) 001383(17)Ow(1) ndash009290(17) 025 05 00198(3)H ndash0139(3) 0191(3) 0454(3) 0055(8)b

Ow(2) ndash002810(10) 032654(9) 014686(10) 001156(15)H(1) 0018(3) 0252(3) 0134(3) 0052(8)b

H(2) ndash0113(3) 0287(3) 0159(3) 0054(7)b

a Fixed during the refinementb Uiso

1 Deposit item AM-14-408 CIF Deposit items are stored on the MSA web site and available via the American Mineralogist Table of Contents Find the article in the table of contents at GSW (ammingeoscienceworldorg) or MSA (wwwminsocamorg) and then click on the deposit link


from each other M(1)O4(H2O)2 octahedra Adjacent chains are connected with each other by the corners of M(2) octahedra The neighboring octahedral layers are connected by PO4 tetrahedra (Fig 7)

diSCuSSioN aNd imPliCatioNS

The comparative crystal chemistry of different minerals with the phosphoferrite structure type has been discussed by Moore et al (1980) All these minerals are orthorhombic phosphates with the general formula M(1)M(2)2(PO4)2(OHH2O)3 where octahedral sites M(1) and M(2) can contain Mn2+ Fe2+ Mg and Fe3+ (Table 8) with minor admixtures of Ca and Al and some other (trace)

components Mn2+ preferably occupies the larger octahedron M(2) but in reddingite both M(1) and M(2) sites are dominantly occupied by Mn2+

Based on interatomic distances and observed trends in site populations Moore et al (1980) assumed the existence of a hy-pothetical reddingite-group mineral with the end-member formula Fe2+Mn2+

2 (PO4)2middot3H2O in which Fe2+ occupies the M(1) site and Mn2+ occupies the M(2) site The discovery of correianevesite confirmed this assumption

Taking into account Moumlssbauer spectroscopy data (Table 1) the results of the crystal structure refinement (Tables 5 and 6) compositional data (Table 2) and general trends in the cation distribution between the sites M(1) and M(2) (Moore et al 1980) the crystal-chemical formula of correianevesite can be written as (Fe0

2+72Mn0

2+20Fe0

3+08)(Mn148Fe0

2+52)(PO4)2 (H2OOH)3 This formula

was derived assuming that the major part of Fe2+ (corresponding to

Table 6 Anisotropic displacement parameters (in Aring2) for correianevesiteAtom U11 U22 U33 U23 U13 U12

M(1) 001124(11) 000880(11) 000930(10) ndash000005(8) ndash000259(8) ndash000117(8)M(2) 001149(9) 000988(9) 000894(8) ndash000086(5) 000013(6) ndash000265(6)P 000643(12) 000743(12) 000752(12) ndash000028(9) 000035(9) ndash000037(9)O(1) 00116(4) 00077(3) 00169(4) ndash00014(3) 00000(3) 00000(3)O(2) 00109(3) 00133(4) 00103(3) 00003(3) 00024(3) ndash00036(3)O(3) 00088(3) 00125(4) 00155(4) ndash00015(3) 00004(3) 00027(3)O(4) 00150(4) 00183(4) 00082(3) ndash00002(3) ndash00019(3) ndash00040(3)Ow(1) 00208(7) 00171(6) 00216(7) ndash00045(5) 0000 0000Ow(2) 00114(4) 00093(4) 00140(4) ndash00003(3) ndash00001(3) ndash00012(3)

Table 7 Selected interatomic distances (Aring) in correianevesiteM(1)ndashO(4) 20413(9) times2 M(2)ndashO(1) 20981(9)M(1)ndashOw(2) 21873(9) times2 M(2)ndashO(2) 21270(9)M(1)ndashO(3) 22812(9) times2 M(2)ndashO(2) 21424(9)ltM(1)ndashOgt 2170 M(2)ndashO(3) 21562(9)PndashO(3) 15362(9) M(2)ndashOw(2) 22235(9)PndashO(4) 15369(9) M(2)ndashOw(1) 24600(10)PndashO(2) 15379(9) ltM(2)ndashOgt 2201PndashO(1) 15399(9) ltPndashOgt 15377

Hydrogen bondsa

Ow(1)ndashH 084(2) Ow(1)ndashHhellipO(4) 3104(4)Ow(2)ndashH(1) 088(3) Ow(2)ndashH(1)hellipO(4) 2865(5)Ow(2)ndashH(2)b 090(3) Ow(2)ndashH(2)hellipO(1) 2539(5)a O-H distances were refined without restraintsb Possibly bifurcated H-bond H(2)hellipO(3) with Ow(2)hellipO(3) distance of 3128 Aring

FiguRe 6 Octahedral layer in the structure of correianevesite M1O6 octahedra are dark M2O6 octahedra are light H atoms are shown with small circles Unit cell is outlined

FiguRe 7 The crystal structure of correianevesite a-b projection Unit cell is outlined

Table 8 Dominant components in cationic sites of reddingite-group minerals

Mineral M(1) M(2)Reddingite Mn2+ Mn2+

Phosphoferrite Fe2+ Fe2+

Landesite Fe3+ Mn2+

Kryzhanovskite Fe3+ Fe3+

Garyanselite Mg Fe3+

Correianevesite Fe2+ Mn2+


Fe12+ by Moumlssbauer data) occupies the smaller octahedron M(1) Note that according to the assumption that Fe12+ corresponds to bivalent iron in the M(2) site the crystal chemical formula would be (Fe2+

052Mn2+041Fe3+

008)(Mn2+129Fe2+

073)(PO4)2(H2OOH)3 and also would correspond to a mineral with the end-member for-mula Fe2+Mn2+

2 (PO4)2middot3H2O However the latter variant of cation distribution is hardly probable taking into account cationndashanion distances

Comparative data for correianevesite and related minerals are given in Table 9 It is important to note that landesite and correianevesite cannot be distinguished by electron microprobe analysis but landesite is characterized by much higher values of refractive indexes as a result of high-Fe3+ content Correianevesite and Fe-bearing reddingite can be distinguished only by means of Moumlssbauer spectroscopy

The presence of acidic OH groups detected by IR spectroscopy data are due to the asymmetric polarization of H2O molecules that form strong hydrogen bond Ow(2)ndashH(2)hellipO(1) [with the distance Ow(2)hellipO(1) of 2539 Aring] and act as proton donors This phenom-enon is very typical for nominally neutral sulfates phosphates and arsenates and results in the dynamic acid-base equilibrium AO4

3ndash + H2O harr HAO4

2ndash + OHndash (A = P As or S) that is usually shifted toward left side (see eg Chukanov et al 2010 2012 Nestola et al 2012) Note that the presence of acid phosphate groups in correianevesite (considered as reddingite before Moumlssbauer data have been obtained) was detected also by means of Raman spec-troscopy (Frost et al 2012) In particular a strong band at 1007 cmndash1 was assigned to symmetric stretching vibrations of HOPO3

2ndash

aCkNowledgmeNtSWe acknowledge Russian Foundation for Basic Researches (Grant No 11-05-

00407-a) for financial support and all members of the IMA Commission on New Minerals Nomenclature and Classification for their helpful suggestions and comments Special thanks also to the Brazilian agencies Fapemig and CNPq (CORGEMA II and Grant No 3062872012-9) We also thank Beda Hofmann Frederic Hatert and Fabrizio Nestola for useful comments

ReFeReNCeS CitedChaves MLSC Scholz R Atencio D and Karfunkel J (2005) Assembleacuteias e

paragecircneses minerais singulares nos pegmatitos da regiatildeo de Galileacuteia (Minas Gerais) Geociecircncias 24 143ndash161 (in Portuguese)

Chukanov NV Mukhanova AA Moumlckel S Belakovskiy DI and Levitskaya LA (2010) Nickeltalmessite Ca2Ni(AsO4)2middot2H2O a new mineral species of the fairfieldite group Bou Azzer Morocco Geology of Ore Deposits 52 606ndash611

Chukanov NV Scholz R Aksenov SM Rastsvetaeva RK Pekov IV Belakovs-kiy DI Krambrock K Paniago RM Righi A Martins RF Belotti FM and Bermanec V (2012) Metavivianite Fe2+Fe3+

2 (PO4)2(OH)2middot6H2O New data and formula revision Mineralogical Magazine 76 725ndash741

Feklichev VG (1989) Diagnostic Constants of Minerals 480 p Nedra Moscow (in Russian)

Frost RL Weier ML and Lyon W (2004) Metavivianite an intermediate mineral phase between vivianite and ferroferristrunzitemdasha Raman spectroscopic study Neues Jahrbuch fuumlr Mineralogie Monatshefte 5 228ndash240

Frost RL Xi Y Scholz R Belotti FM and Lagoeiro LE (2012) Chemistry Raman and infrared spectroscopic characterization of the phosphate mineral red-dingite (MnFe)3(PO4)2(H2OOH)3 a mineral found in lithium-bearing pegmatite Physics and Chemistry of Minerals 39 803ndash810

Kleber W and Donnay JDH (1961) The heteromorphism of phosphoferrite-reddin-gite Zeitschrift fuumlr Kristallografie 115 161ndash168

Moore PB (1964) Investigations of landesite American Mineralogist 49 1122ndash1125mdashmdashmdash (1971) The Fe2+(H2O)n(PO4)2 homologous series crystal-chemical relationships

and oxidized equivalents American Mineralogist 56 1ndash17Moore PB and Araki T (1976) A mixed-valence solid-solution series Crystal struc-

tures of phosphoferrite Fe3II(H2O)3[PO4]2 and kryzhanovskite Fe3

III(OH)3[PO4]2 Inorganic Chemistry 15 316ndash321

Moore PB Araki T and Kampf AR (1980) Nomenclature of the phosphoferrite structure type Refinements of landsite and kryzhanovskite Mineralogical Mag-azine 43 789ndash795

Nestola F Caacutemara F Chukanov NV Atencio D Coutinho JMV Contreira Filho RR and Faumlrber G (2012) Witzkeite A new rare nitrate-sulphate mineral from a guano deposit at Punta de Lobos Chile American Mineralogist 97 1783ndash1787

Pedrosa-Soares AC Campos CM De Noce CM Silva LC Da Novo TA Roncato J Medeiros SM Castantildeeda C Queiroga GN Dantas E Dussin IA and Alkmim F (2011) Late Neoproterozoic-Cambrian granitic magmatism in Araccediluaiacute orogen (Brazil) the Eastern Brazilian Pegmatite Province and related mineral resources Geological Society Special Publication 350 25ndash51

Sheldrick GM (2008) A short history of SHELX Acta Crystallographica A64 112ndash122

Tennyson C (1954) Phosphoferrit und Reddingit von Hagendorf Neues Jahrbuch fuumlr Mineralogie Abhandlungen 87 185ndash217

Manuscript received august 12 2013Manuscript accepted noveMber 9 2013Manuscript handled by beda hofMann

Table 9 Comparative data for correianevesite and related reddingite-group minerals Correianevesite Reddingite Phosphoferrite LandesiteFormula Fe2+Mn2+

2 (PO4)23H2O Mn2+Mn22+(PO4)23H2O Fe2+Fe2

2+(PO4)23H2O Fe3+Mn22+(PO4)2(OH)2H2O

Space group Pbna Pbna Pbna Pbnaa Aring 94887 9489ndash949 9460 9458b Aring 101149 1008ndash10126 10024 10185c Aring 87062 870ndash8710 8670 8543Z 4 4 4 4Strong lines of the X-ray powder-diffraction pattern d Aring (I ) 508 (43) 428 (70) 425 (70) 5096 (54) 4761 (21) 320 (100) 318 (100) 4284 (27) 4314 (28) 2737 (80) 2724 (80) 3207 (100) 3220 (100) 2657 (70) 2639 (70) 3163 (35) 3125 (25) 2422 (70) 2408 (70) 3090 (23) 2756 (35) 2234 (70) 2222 (70) 2758 (29) 2686 (25) 1625 (70) 1615 (70) 2630 (24) 2436 (22) 2233 (23) Optical data α 1661(5) 1643ndash1658 1663ndash1672 1720β 1673(5) 1648ndash1664 1674ndash1680 1728γ 1703(5) 1674ndash1685 1699ndash1700 1735Optical sign 2V deg (+) 70(10) (+) 41ndash80 (+) 66ndash70 (ndash) largeDensity 325 (meas) 310ndash324 (meas) 310ndash329 (meas) 3026ndash303 (meas) gcm3 3275 (calc) 326 (calc) 332 (calc) 3210 (calc)Mohs hardness 3frac12 3ndash3frac12 3ndash4frac12 3ndash3frac12References This work Tennyson (1954) Kleber and Donnay Tennyson (1954) Kleber and Donnay (1961) Moore (1964) Moore et al (1961) Feklichev (1989) Frost et al (2012) Moore and Araki (1976) Moore (1971) (1980) Feklichev (1989) Moore et al (1980) Feklichev (1989)


FiguRe 1 Bipyramidal crystals of correianevesite on hureaulite Field of view 6 mm Photo Carlos Menezes

and the formation of a complex secondary phosphate assemblage described by Chaves et al (2005)

The primary mineral association is represented by quartz muscovite microcline schorl almandine-spessartine spodumene and triphylite The secondary association is mainly composed by albite Ta and Nb oxides hydrothermal beryl cassiterite pyrite and numerous phosphates formed as a result of alteration of triphylite (Chaves et al 2005) The paragenetic assemblage of secondary phosphates is composed by lithiophillite correia-nevesite hureaulite frondelite fluorapatite eosphorite fairfieldite gormanite and vivianite

The new mineral is named in memory of Joseacute Marques Correia Neves (1929ndash2011) professor of the Instituto de Geociecircncias Universidade Federal de Minas Gerais who was the most active geoscientist in the study of Brazilian pegmatites especially in the region of Conselheiro Pena and Araccediluai as well as in Alto Ligonha in Mozambique where he discovered hafnon the Hf analog of zircon

The type specimen of correianevesite (a part of the holotype) is deposited in the mineralogical collections of the Museu de Ciecircncia e Teacutecnica Escola de Minas Universidade Federal de Ouro Preto Praccedila Tiradentes Centro 35400-000 ndash Ouro Preto MG Brazil with the registration number SAA-081B

geNeRal aPPeaRaNCe aNd PhySiCal PRoPeRtieS

Correianevesite occurs as light grayish-brown to reddish-brown transparent bipyramidal crystals up to 4 mm in size (Fig 1) in cavities of triphylite The only form observed is 111 The streak is white and the luster is vitreous The mineral is non-fluorescent under ultraviolet light Mohs hardness is 3frac12 Cleavage is poor on (010) Fracture is laminated uneven across cleavage The density measured by flotation in heavy liquids is 325(2) gcm3 The calculated density is 3275 gcm3 based on the empirical formula and unit-cell parameters obtained from the single-crystal X-ray diffraction data

Thermal data for correianevesite were obtained using a Shi-madzu analyzer in a nitrogen atmosphere at a gas flow rate of 50 cm3 minndash1 Differential thermal analysis (DTA) and thermogravi-metric (TG) analyses were carried out simultaneously Crushed samples with 1488 mg weight were heated in an open platinum

crucible at a rate of 10 degC minndash1 up to a temperature of 800 degC The TG curve of correianevesite in nitrogen atmosphere is given in Figure 2

The lowered weight loss of 1045 obtained by TG as compared with H2O content of 126 wt obtained by gas chro-matography of products of ignition (see below) is explained by self-oxidation (a phenomenon typical of Fe2+- and Mn2+-phosphates see eg Frost et al 2004 Chukanov et al 2012) in accordance with the following simplified schemes (M = Fe Mn)

2M2+ + H2O rarr 2M3+ + O2ndash + H2

2M2+ + 2H2O rarr 2M3+ + 2OHndash + H2

These processes correspond to exothermic effects in the DTA curve (Fig 3) and may be explained by the partial oxidation of Fe2+ to Fe3+

To obtain infrared (IR) absorption spectrum correianevesite powder was mixed with anhydrous KBr pelletized and analyzed using an ALPHA FTIR spectrometer (Bruker Optics) at the resolu-tion of 4 cmndash1 and number of scans of 16 IR spectrum of analogous pellet of pure KBr was used as a reference

Absorption bands in the IR spectrum of correianevesite (Fig 4) and their assignments are (cmndash1 s = strong band w = weak band sh = shoulder) 3457 3200 (O-H stretching vibrations of H2O molecules and OH anions hydrogen bonds of medium strengths) 2530 2033w 1890 (vibrations of the fragments O-HhellipO-P very strong hydrogen bonds of acidic OH groups) 2247w (overtone of asymmetric stretching vibrations of PO4

3ndash anions) 1636w 1575 (bending vibrations of H2O molecules) 1054s 1013s (asymmetric stretching vibrations of PO4

3ndash anions) 758 750sh 661 (librational vibrations of H2O molecules forming strong hydrogen bonds) 598 570 555sh (O-P-O bending vibrations of PO4

3ndash anions) 476w 417w 384w (mixed lattice vibrations)

Bands of B- C- and N-bearing groups are absent in the IR spectrum of correianevesite The nature of anomalously strong hydrogen bonds is discussed below

The IR spectrum of correianevesite is comparable to those of the isostructural minerals phosphoferrite and reddingite

Moumlssbauer spectra were collected in constant acceleration

FiguRe 2 TG curve of correianevesite obtained in nitrogen atmosphere at a heating rate of 10 degC minndash1





Fe2+125Fe3+











Fe2O3a 154

P2O5 3459 3419ndash3502 027 LaPO4














Formula (Fe02+

72Mn02+

20Fe03+

08)(Mn148Fe02+




Atom xa yb zc Ueq

M(1) = Fe080Mn020a 00 00 00 000978(6)

M(2) = Mn074Fe026a 0065331(19) 0097199(18) 063633(2) 001010(5)


Ow(2) ndash002810(10) 032654(9) 014686(10) 001156(15)H(1) 0018(3) 0252(3) 0134(3) 0052(8)b

H(2) ndash0113(3) 0287(3) 0159(3) 0054(7)b











2+72Mn0

2+20Fe0

3+08)(Mn148Fe0






Hydrogen bondsa







Landesite Fe3+ Mn2+






052Mn2+041Fe3+

008)(Mn2+129Fe2+







2ndash
























2+(PO4)23H2O Fe3+Mn22+(PO4)2(OH)2H2O






Fe2+125Fe3+











Fe2O3a 154

P2O5 3459 3419ndash3502 027 LaPO4














Formula (Fe02+

72Mn02+

20Fe03+

08)(Mn148Fe02+




Atom xa yb zc Ueq

M(1) = Fe080Mn020a 00 00 00 000978(6)

M(2) = Mn074Fe026a 0065331(19) 0097199(18) 063633(2) 001010(5)


Ow(2) ndash002810(10) 032654(9) 014686(10) 001156(15)H(1) 0018(3) 0252(3) 0134(3) 0052(8)b

H(2) ndash0113(3) 0287(3) 0159(3) 0054(7)b











2+72Mn0

2+20Fe0

3+08)(Mn148Fe0






Hydrogen bondsa







Landesite Fe3+ Mn2+






052Mn2+041Fe3+

008)(Mn2+129Fe2+







2ndash
























2+(PO4)23H2O Fe3+Mn22+(PO4)2(OH)2H2O









Formula (Fe02+

72Mn02+

20Fe03+

08)(Mn148Fe02+




Atom xa yb zc Ueq

M(1) = Fe080Mn020a 00 00 00 000978(6)

M(2) = Mn074Fe026a 0065331(19) 0097199(18) 063633(2) 001010(5)


Ow(2) ndash002810(10) 032654(9) 014686(10) 001156(15)H(1) 0018(3) 0252(3) 0134(3) 0052(8)b

H(2) ndash0113(3) 0287(3) 0159(3) 0054(7)b











2+72Mn0

2+20Fe0

3+08)(Mn148Fe0






Hydrogen bondsa







Landesite Fe3+ Mn2+






052Mn2+041Fe3+

008)(Mn2+129Fe2+







2ndash
























2+(PO4)23H2O Fe3+Mn22+(PO4)2(OH)2H2O










2+72Mn0

2+20Fe0

3+08)(Mn148Fe0






Hydrogen bondsa







Landesite Fe3+ Mn2+






052Mn2+041Fe3+

008)(Mn2+129Fe2+







2ndash
























2+(PO4)23H2O Fe3+Mn22+(PO4)2(OH)2H2O




052Mn2+041Fe3+

008)(Mn2+129Fe2+







2ndash
























2+(PO4)23H2O Fe3+Mn22+(PO4)2(OH)2H2O


Correianevesite, Fe2+Mn22+(PO4)2·3H2O, a new reddingite-group … · 2014. 4. 9. · The...

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