scholarly journals Davidbrownite-(NH4), (NH4,K)5(V4+O)2(C2O4)[PO2.75(OH)1.25]4·3H2O, a new phosphate–oxalate mineral from the Rowley mine, Arizona, USA

2019 ◽  
Vol 83 (6) ◽  
pp. 869-877
Author(s):  
Anthony R. Kampf ◽  
Mark A. Cooper ◽  
George R. Rossman ◽  
Barbara P. Nash ◽  
Frank. C. Hawthorne ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
New Mineral ◽  
Monovalent Cations ◽  
New Mineral Species ◽  
Raman And Infrared Spectroscopy ◽  
Mohs Hardness ◽  
A Chain ◽  
Light Green

AbstractDavidbrownite-(NH4), (NH4,K)5(V4+O)2(C2O4)[PO2.75(OH)1.25]4·3H2O, is a new mineral species from the Rowley mine, Maricopa County, Arizona, USA. It occurs in an unusual bat-guano-related, post-mining assemblage of phases that include a variety of vanadates, phosphates, oxalates and chlorides, some containing NH4+. Other secondary minerals found in association with davidbrownite-(NH4) are antipinite, fluorite, mimetite, mottramite, quartz, rowleyite, salammoniac, struvite, vanadinite, willemite and wulfenite. Crystals of davidbrownite-(NH4) are light green–blue needles or narrow blades up to ~0.2 mm long. The streak is white, the lustre is vitreous, Mohs hardness is ca. 2, tenacity is brittle and fracture is splintery. There are two good cleavages in the [010] zone, probably {100} and {001}. The measured density is 2.12(2) g cm–3. Davidbrownite-(NH4) is optically biaxial (+) with α = 1.540(2), β = 1.550(5) and γ = 1.582(2) (white light); 2V = 58.5(5)°; moderate r > v dispersion; and orientation Z = b and Y ≈ a. Pleochroism: X = pale blue, Y = nearly colourless, Z = light blue; and Y < X < Z. Electron microprobe analysis gave the empirical formula [(NH4)3.11K1.73Na0.09]Σ4.93[(V4+1.92Mg0.01Al0.02)Σ1.95O2](C2O4) [(P3.94As0.12)Σ4.06O10.94(OH)5.06]·3H2O, with the C and H content provided by the crystal structure. Raman and infrared spectroscopy confirmed the presence of NH4 and C2O4. Davidbrownite-(NH4) is monoclinic, P21/c, with a = 10.356(6), b = 8.923(5), c = 13.486(7) Å, β = 92.618(9)°, V = 1244.9(12) Å3 and Z = 2. The crystal structure of davidbrownite-(NH4) (R1 = 0.0524 for 2062 Io > 2σI reflections) consists of a chain structural unit with the formula {(V4+O)2(C2O4)[PO2.75(OH)1.25]4}5–, and a disordered interstitial complex containing five large monovalent cations (NH4+ and K+) and three H2O groups pfu. Strong hydrogen bonds form links within and between the chains.

scholarly journals Lead-antimony sulfosalts from Tuscany (Italy). XVI. Carducciite, (AgSb)Pb6(As,Sb)8S20, a new Sb-rich derivative of rathite from the Pollone mine, Valdicastello Carducci: occurrence and crystal structure

2014 ◽  
Vol 78 (7) ◽  
pp. 1775-1793 ◽  
Author(s):  
Cristian Biagioni ◽  
Paolo Orlandi ◽  
Yves Moëlo ◽  
Luca Bindi
Keyword(s):  
Crystal Structure ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structural Formula ◽  
Structure Study ◽  
New Mineral ◽  
New Mineral Species ◽  
Reflected Light ◽  
Coupled Substitution ◽  
Mohs Hardness

AbstractThe new mineral species carducciite, (AgSb)Pb6(As,Sb)8S20, has been discovered in the baryte-pyrite- (Pb-Ag-Zn) deposit of the Pollone mine, near Valdicastello Carducci, Apuan Alps, Tuscany, Italy. It occurs as black metallic prismatic crystals, up to 0.5 mm long, associated with pyrite and sterryite. Its Vickers hardness (VHN10) is 61 kg/mm2 (range: 52–66), corresponding to a Mohs hardness of ~2½–3. In reflected light, carducciite is dark grey in colour, moderately bireflectant; internal reflections are very weak and deep red in colour. Reflectance percentages for the four COM wavelengths [Rmin, Rmax (%) (λ)] are: 35.8, 40.8 (471.1 nm), 33.7, 39.0 (548.3 nm), 32.7, 37.6 (586.6 nm) and 30.4, 35.1 (652.3 nm). Electron microprobe analysis gives (wt.% – mean of six analyses): Ag 3.55(12), Tl 0.13(3), Pb 41.90(42), Sb 17.79(19), As 12.41(14), S 22.10(17), total 97.9(6). On the basis of ΣMe = 16 a.p.f.u., the chemical formula is Ag0.96Tl0.02Pb5.91As4.84Sb4.27S20.14. The main diffraction lines, corresponding to multiple hkl indices, are (relative visual intensity): 3.689 (s), 3.416 (s), 3.125 (s), 2.989 (s), 2.894 (s), 2.753 (vs), 2.250 (s). The crystal-structure study gives a monoclinic unit cell, space group P21/c, with a 8.4909(3), b 8.0227(3), c 25.3957(9) Å, β 100.382(2)°, V 1701.63(11) Å3, Z = 2. The crystal structure has been solved and refined to a final R1 = 0.063 on the basis of 4137 observed reflections. It can be described within the framework of the sartorite homologous series, as formed by chemically twinned layers of the dufrénoysite type. The simplified idealized structural formula, based on 20 sulfur atoms, can ideally be written as (AgSb)Pb6(As,Sb)Σ=8S20. Carducciite is an (Ag,Sb)-rich homeotype of dufrénoysite, stabilized by the complete coupled substitution 2 Pb2+ = Ag+ + Sb3+ on a specific site of the crystal structure. Together with barikaite, it belongs to the rathite sub-group of P21/c homeotypes of dufrénoysite, of which the crystal chemistry is discussed. The distribution of Ag, coupled with As or Sb on specific sites, appears to be the main criterion for the distinction between the three species of this sub-group.

Oxycalcioroméite, Ca2Sb2O6O, from Buca della Vena mine, Apuan Alps, Tuscany, Italy: a new member of the pyrochlore supergroup

2013 ◽  
Vol 77 (7) ◽  
pp. 3027-3037 ◽  
Author(s):  
C. Biagioni ◽  
P. Orlandi ◽  
F. Nestola ◽  
S. Bianchin
Keyword(s):  
Crystal Structure ◽  
Detection Limit ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structure Study ◽  
New Mineral ◽  
X Ray ◽  
New Mineral Species ◽  
Single Crystal Study ◽  
Apuan Alps

AbstractThe new mineral species oxycalcioroméite, Ca2Sb5+2O6O, has been discovered at the Buca della Vena mine, Stazzema, Apuan Alps, Tuscany, Italy. It occurs as euhedral octahedra, up to 0.1 mm in size, embedded in dolostone lenses in the baryte + pyrite + iron oxides ore. Associated minerals are calcite, cinnabar, derbylite, dolomite, hematite, 'mica', pyrite, sphalerite and 'tourmaline'. Oxycalcioroméite is reddish-brown in colour and transparent. It is isotropic, with ncalc = 1.950.Electron microprobe analysis gave (wt.%; n = 6) Sb2O5 63.73, TiO2 3.53, SnO2 0.28, Sb2O3 10.93, V2O3 0.68, Al2O3 0.28, PbO 0.68, FeO 5.52, MnO 0.13, CaO 13.68, Na2O 0.83, F 1.20, O = F – 0.51, total 100.96. No H2O, above the detection limit, was indicated by either infrared or micro-Raman spectroscopies. The empirical formula, based on 2 cations at the B site, is (Ca1.073Fe2+0.338Sb3+0.330Na0.118Pb0.013Mn0.008)Σ=1.880(Sb5+1.734Ti0.194V0.040Al0.024Sn0.008)Σ=2.000(O6.682F0.278)Σ6.960. The crystal structure study gives a cubic unit cell, space group Fdm, with a 10.3042(7) Å, V 1094.06(13) Å3, Z = 8. The five strongest X-ray powder diffraction lines are [d(Å)I(visually estimated)(hkl)]: 3.105(m)(311); 2.977(s)(222); 2.576(m)(400); 1.824(ms)(440); and 1.556(ms)(622). The crystal structure of oxycalcioroméite has been solved by X-ray single-crystal study on the basis of 114 observed reflections, with a final R1 = 0.0114. It agrees with the general features of the members of the pyrochlore supergroup.

Wooldridgeite, Na2(P2O7)2(H2O)10: A new mineral from Judkins Quarry, Warwickshire, England

1999 ◽  
Vol 63 (1) ◽  
pp. 13-16 ◽  
Author(s):  
F. C. Hawthorne ◽  
M. A. Cooper ◽  
D. I. Green ◽  
R. E. Starkey ◽  
A. C. Roberts ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Infrared Absorption Spectrum ◽  
Short Wave ◽  
New Mineral ◽  
Calculated Density ◽  
X Ray ◽  
Mohs Hardness ◽  
Unit Formula

AbstractWooldridgeite, ideally Na2(P2O7)2(H2O)10, orthorhombic, a = 11.938(1), b = 32.854(2), c = 11.017(1) Å , V = 4321.2(8) Å3, a:b:c = 0.3634:1:0.3353, space group Fdd2, Z = 8, is a new mineral from Judkins Quarry, Nuneaton, Warwickshire, England. Associated minerals are calcite, chalcopyrite, bornite and baryte. It occurs as equant crystals forming rhombic dipyramids; no twinning was observed. It is transparent blue-green with a very pale-blue streak, a vitreous lustre, and does not fluoresce under long- or short-wave ultraviolet light. Wooldridgeite has a Mohs hardness of 2–3, is brittle with an irregular fracture, and has no cleavage. The calculated density is 2.279 g/cm3. In transmitted light, wooldridgeite is colourless, non-pleochroic, and shows no dispersion. It is biaxial negative with α = 1.508(1), β = 1.511(1), γ = 1.517(1), 2V(meas.) = 76.2(5), 2V(calc.) = 71(10)8, X = b, Y = c, Z = a. The strongest five reflections in the X-ray powder diffraction pattern are [d(Å), (I), (hkl)]: 8.23(30)(040), 6.52(100)(131), 4.05(40)(260), 3.255(40)(262); 2.924(40)(371). Electron-microprobe analysis of wooldridgeite gave P2O5 39.37, CuO 20.24, MgO 0.24, CaO 7.73, Na2O 8.33, K2O 0.17, H2O(calc.) 24.72, sum 100.80 wt.%; the corresponding unit formula (based on 24 anions) is (Na1.96K0.03)Ca1.00(Cu1.85Mg0.04)P4.04O14(H2O)10 where the H2O groups were assigned from knowledge of the crystal structure; the infrared absorption spectrum also indicates the presence of H2O in the structure. The mineral is named for James Wooldridge (1923–1995), a fervent amateur mineral collector who discovered this mineral.

scholarly journals Rüdlingerite, Mn2+2V5+As5+O7·2H2O, a New Species Isostructural with Fianelite

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 960
Author(s):  
Philippe Roth ◽  
Nicolas Meisser ◽  
Fabrizio Nestola ◽  
Radek Škoda ◽  
Fernando Cámara ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Mineral Deposits ◽  
New Mineral ◽  
Chemical Formula ◽  
Manganese Mineral ◽  
New Mineral Species ◽  
Hematite Ore ◽  
A New Species

The new mineral species rüdlingerite, ideally Mn2+2V5+As5+O7·2H2O, occurs in the Fianel mine, in Val Ferrera, Grisons, Switzerland, a small Alpine metamorphic Mn deposit. It is associated with ansermetite and Fe oxyhydroxide in thin fractures in Triassic dolomitic marbles. Rüdlingerite was also found in specimens recovered from the dump of the Valletta mine, Canosio, Cuneo, Piedmont, Italy, where it occurs together with massive braccoite and several other As- and V-rich phases in richly mineralized veins crossing the quartz-hematite ore. The new mineral displays at both localities yellow to orange, flattened elongated prismatic, euhedral crystals measuring up to 300 μm in length. Electron-microprobe analysis of rüdlingerite from Fianel gave (in wt%): MnO 36.84, FeO 0.06, As2O5, 25.32, V2O5 28.05, SiO2 0.13, H2Ocalc 9.51, total 99.91. On the basis of 9 O anions per formula unit, the chemical formula of rüdlingerite is Mn1.97(V5+1.17 As0.83Si0.01)Σ2.01O7·2H2O. The main diffraction lines are [dobs in Å (Iobs) hkl]: 3.048 (100) 022, 5.34 (80) 120, 2.730 (60) 231, 2.206 (60) 16-1, 7.28 (50) 020, 2.344 (50) 250, 6.88 (40) 110, and 2.452 (40) 320. Study of the crystal structure showcases a monoclinic unit cell, space group P21/n, with a = 7.8289(2) Å, b = 14.5673(4) Å, c = 6.7011(2) Å, β = 93.773(2)°, V = 762.58(4) Å3, Z = 4. The crystal structure has been solved and refined to R1 = 0.041 on the basis of 3784 reflections with Fo > 4σ(F). It shows Mn2+ hosted in chains of octahedra that are subparallel to [-101] and bound together by pairs of tetrahedra hosted by V5+ and As5+, building up a framework. Additional linkage is provided by hydrogen-bonding through H2O coordinating Mn2+ at the octahedra. One tetrahedrally coordinated site is dominated by V5+, T(1)(V0.88As0.12), corresponding to an observed site scattering of 24.20 electrons per site (eps), whereas the second site is strongly dominated by As5+,T(2)(As0.74V0.26), with, accordingly, a higher observed site scattering of 30.40 eps. The new mineral has been approved by the IMA-CNMNC and named for Gottfried Rüdlinger (born 1919), a pioneer in the 1960–1980s, in the search and study of the small minerals from the Alpine manganese mineral deposits of Grisons.

Coiraite, (Pb,Sn2+)12.5As3Fe2+Sn4+5 S28: a franckeite-type new mineral species from Jujuy Province, NW Argentina

2008 ◽  
Vol 72 (5) ◽  
pp. 1083-1101 ◽  
Author(s):  
W. H. Paar ◽  
Y. Moëlo ◽  
N. N. Mozgova ◽  
N. I. Organova ◽  
C. J. Stanley ◽  
...  
Keyword(s):  
Low Temperature ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Mineral Species ◽  
New Mineral ◽  
Hydrothermal Solutions ◽  
X Ray ◽  
New Mineral Species ◽  
Primary Mineral ◽  
The Ideal

AbstractCoiraite, ideally (Pb,Sn2+)12.5As3Fe2+Sn4+S28, occurs as an economically important tin ore in the large Ag-Sn-Zn polymetallic Pirquitas deposit, Jujuy Province, NW-Argentina. The new mineral species is the As derivative of franckeite and belongs to the cylindrite group of complex Pb sulphosalts with incommensurate composite-layered structures. It is a primary mineral, frequently found in colloform textures, and formed from hydrothermal solutions at low temperature. Associated minerals are franckeite, cylindrite, pyrite-marcasite, as well as minor amounts of hocartite, Ag-rich rhodostannite. arsenopyrite and galena. Laminae of coiraite consist of extremely thin bent platy crystals up to 50 urn long. Electron microprobe analysis (n = 31) gave an empirical formula Pb11.21As2.99Ag0.13Fe1.10Sn6.13S28.0 close to the ideal formula (Pb11.3Sn2+1.2)Σ=12.5As3Fe2+Sn4+S28. Coiraite has two monoclinic sub-cells, Q (pseudotetragonal) and H (pseudohexagonal). Q: a 5.84(1) Å, b 5.86(1) Å, c 17.32(1) Å, β 94.14(1)°, F 590.05(3) Å3, Z = 4, a:b:c = 0.997:1:2.955; H (orthogonal setting): a 6.28(1) Å, b 3.66(1) Å, c 17.33(1) Å, β 91.46(1)°, V398.01(6) Å3, Z = 2, a∶b∶c = 1.716∶1∶4.735. The strongest Debye-Scherrer camera X-ray powder-diffraction lines [d in Å, (I), (hkl)] are: 5.78, (20), (Q and H 003); 4.34, (40), (Q 004); 3.46, (30), (Q and H 005); 3.339, (20), (Q 104); 2.876, (100), (Q and H 006); 2.068, (60), (Q 220).

Bicapite, KNa2Mg2(H2PV145+O42)·25H2O, a new polyoxometalate mineral with a bicapped Keggin anion from the Pickett Corral mine, Montrose County, Colorado, U.S.A.

2019 ◽  
Vol 104 (12) ◽  
pp. 1851-1856 ◽  
Author(s):  
Anthony R. Kampf ◽  
John M. Hughes ◽  
Barbara P. Nash ◽  
Joe Marty
Keyword(s):  
Crystal Structure ◽  
Electron Probe ◽  
Structural Unit ◽  
New Mineral ◽  
Charge Balance ◽  
Keggin Anion ◽  
Naturally Occurring ◽  
New Mineral Species ◽  
Mohs Hardness ◽  
Measured Density

Abstract Bicapite, KNa2Mg2(H2PV145+O42)·25H2O, is a new mineral species (IMA2018-048) discovered at the Pickett Corral mine, Montrose County, Colorado, U.S.A. Bicapite occurs as square tablets up to about 0.2 mm on edge on montroseite-corvusite-bearing sandstone. Crystals are dark red-brown, often appearing black. The streak is orange, and the luster is vitreous. Bicapite is brittle, has a Mohs hardness of 1½, and displays one excellent cleavage on {100}. The measured density is 2.44(2) g/cm3. Bicapite is uniaxial (+), ω = 1.785(5), ε ≈ 1.81 (white light); pleochroism is red-brown; E &gt; O, slight. The electron probe microanalysis and results of the crystal structure determination provided the empirical formula (based on 67 O apfu) (K1.23Na2.23Mg1.48)Σ4.94[H2.51P1.02(V13.915+Mo0.076+)Σ13.98O42]·25H2O. Bicapite is tetragonal, I4/m, with a = 11.5446(12) Å, c = 20.5460(14) Å, V = 2738.3(6) Å3, and Z = 2. The strongest four lines in the diffraction pattern are [d in Å (I) (hkl)]: 10.14 (100) (002,101); 2.978 (29) (134,206); 2.809 (11) (305); and 2.583 (11) (420,008). The atomic arrangement of bicapite was solved and refined to R1 = 0.0465 for 1008 independent reflections with I &gt; 2σI. The structural unit is a [H2PV125+O40(V5+O)2]7– heteropolyanion composed of 12 distorted VO6 octahedra surrounding a central PO4 tetrahedron and capped on opposite sides by two VO5 square pyramids; the structural unit is a modification of the α-isomer of the Keggin anion, [XM12O40]n–. Charge balance in the structure is maintained by the [KNa2Mg2(H2O)25]7+ interstitial complex. The name bicapite is in recognition of this being the only known mineral with a structure based on a bicapped Keggin anion. The discovery of bicapite and numerous other natural polyoxometalate compounds in the Colorado Plateau uranium/vanadium deposits make that the most productive region found to date for naturally occurring polyoxometalate compounds.

scholarly journals Mineralogy of Silicate-Natrophosphate Immiscible Inclusion in Elga IIE Iron Meteorite

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 437
Author(s):  
Victor V. Sharygin
Keyword(s):  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Liquid Immiscibility ◽  
Iron Meteorite ◽  
New Mineral ◽  
Rare Type ◽  
Fine Grained ◽  
New Mineral Species ◽  
Silicate Inclusions ◽  
Dominant Phase

Rare type of silicate inclusions found in the Elga iron meteorite (group IIE) has a very specific mineral composition and shows silicate (≈90%)–natrophosphate (≈10%) liquid immiscibility due to meniscus-like isolation of Na-Ca-Mg-Fe phosphates. The 3 mm wide immiscible inclusion has been first studied in detail using optical microscopy, scanning electron microscopy, electron microprobe analysis and Raman spectroscopy. The silicate part of the inclusion contains fine-grained quartz-feldspar aggregate and mafic minerals. The relationships of feldspars indicate solid decay of initially homogenous K-Na-feldspar into albite and K-feldspar with decreasing of temperature. Some mafic minerals in the silicate part are exotic in composition: the dominant phase is an obertiite-subgroup oxyamphibole (amphibole supergroup), varying from ferri-obertiite NaNa2Mg3Fe3+Ti[Si8O22]O2 to hypothetical NaNa2Mg3Fe2+0.5Ti1.5[Si8O22]O2; minor phases are the aenigmatite-subgroup mineral (sapphirine supergroup) with composition close to median value of the Na2Fe2+5TiSi6O18O2-Na2Mg5TiSi6O18O2 join, orthopyroxene (enstatite), clinopyroxene of the diopside Ca(Mg,Fe)Si2O6–kosmochlor NaCrSi2O6-Na(Mg,Fe)0.5Ti0.5Si2O6 series and chromite. The alteration phases are represented by Fe-dominant chlorite, goethite and hydrated Na2O-rich (2.3–3.3 wt.%) Fe-phosphate close to vivianite. Natrophosphate part consists of aggregate of three orthophosphates (brianite, czochralskiite, marićite) and minor Na-Cr-Ti-clinopyroxene, pentlandite, rarely taenite. Czochralskiite Na4Ca3Mg(PO4)4 is rich in FeO (2.3–5.1 wt.%) and MnO (0.4–1.5 wt.%). Brianite Na2CaMg(PO4)2 contains FeO (3.0–4.3 wt.%) and MnO (0.3–0.7 wt.%) and marićite NaFe(PO4) bears MnO (5.5–6.2 wt.%), MgO (5.3–6.2 wt.%) and CaO (0.5–1.5 wt.%). The contact between immiscible parts is decorated by enstatite zone in the silicate part and diopside–kosmochlor clinopyroxene zone in the natrophosphate ones. The mineralogy of the studied immiscible inclusion outlines three potentially new mineral species, which were first identified in meteorites: obertiite–related oxyamphibole NaNa2Mg3Fe2+0.5Ti1.5[Si8O22]O2, Mg-analog of aenigmatite Na2Mg5TiSi6O18O2 and Na-Ti-rich clinopyroxene Na(Mg,Fe)0.5Ti0.5Si2O6.

Meieranite, Na2Sr3MgSi6O17, a New Mineral from the Wessels Mine, Kalahari Manganese Fields, South Africa

2019 ◽  
Vol 57 (4) ◽  
pp. 457-466 ◽  
Author(s):  
Hexiong Yang ◽  
Xiangping Gu ◽  
Robert T. Downs ◽  
Stanley H. Evans ◽  
Jaco J. Van Nieuwenhuizen ◽  
...  
Keyword(s):  
South Africa ◽  
Empirical Formula ◽  
Microprobe Analysis ◽  
New Mineral ◽  
Cell Parameters ◽  
New Mineral Species ◽  
General Chemical ◽  
Northern Cape ◽  
Coupled Substitution ◽  
Mohs Hardness

Abstract A new mineral species, meieranite, ideally Na2Sr3MgSi6O17, has been found in the Wessels mine, Kalahari Manganese Fields, Northern Cape Province, South Africa. It occurs in isolated aggregates embedded in a matrix mainly of sugilite, along with minor aegirine and pectolite. Crystals of meieranite are up to 0.5 × 0.5 × 0.4 mm in size. No twinning is observed. The mineral is light blue to blue in transmitted and under incident lights, transparent with white streak, and has vitreous luster. It is brittle and has a Mohs hardness of 5.5; cleavage is good on {010} and no parting was observed. The measured and calculated densities are 3.41(3) and 3.410 g/cm3, respectively. Optically, meieranite is biaxial (–), with α = 1.610(1), β = 1.623(1), γ = 1.630(1) (white light), 2V (meas.) = 70(1)°, 2V (calc.) = 72°. The calculated compatibility index based on the empirical formula is –0.007 (superior). An electron microprobe analysis yields an empirical formula (based on 17 O apfu) of Na1.96(Sr2.91Ba0.03Ca0.03Pb0.02)Σ2.99(Mg0.62Mn0.28Co0.07Fe0.01)Σ0.98Si6.03O17, which can be simplified to Na2Sr3MgSi6O17. Meieranite is orthorhombic, with space group P21nb and unit-cell parameters a 7.9380(2), b 10.4923(3), c 18.2560(6) Å, and V 1520.50(8) Å3. Its crystal structure is characterized by two kinds of layers that alternate along [010]: layers of corner-sharing SiO4 and M2+O4 tetrahedra (M2+ = Mg, Mn, Co, Fe) and layers of NaO6 and SrO8 polyhedra. The tetrahedral layers consist of eight-, five-, and four-membered rings and are composed of [Si6O17] ribbons (parallel to [101]) linked together by MO4 tetrahedra. Most remarkably, the structure of meieranite is topologically identical to that of the nordite group of minerals, which has the general chemical formula Na3SrR3+M2+Si6O17, where R = Ce and La and M = Zn, Fe, and Mn. Accordingly, chemically, meieranite may be obtained through the coupled substitution of 2Sr2+ for (Na+ + R3+) in nordite.

Badakhshanite-(Y), Y2Mn4Al(Si2B7BeO24), a new mineral species of the perettiite group from a granite miarolic pegmatite in Eastern Pamir, the Gorno Badakhshan Autonomous Oblast, Tajikistan

2020 ◽  
Vol 58 (3) ◽  
pp. 381-394
Author(s):  
Leonid A. Pautov ◽  
Mirak A. Mirakov ◽  
Fernando Cámara ◽  
Elena Sokolova ◽  
Frank C. Hawthorne ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Close Association ◽  
Coarse Grained ◽  
New Mineral ◽  
Orthorhombic Space Group ◽  
Calculated Density ◽  
Conchoidal Fracture ◽  
New Mineral Species ◽  
Mohs Hardness ◽  
Cation Sites

ABSTRACT Badakhshanite-(Y), ideally Y2Mn4Al(Si2B7BeO24), is a tetrahedral sheet-structure mineral found in the Dorozhny (Road) miarolitic granitic pegmatite within the Kukurt pegmatite field 45 km E of Murghab, Eastern Pamir, Gorno-Badakhshan Autonomous Oblast, Tajikistan. Badakhshanite-(Y) occurs in medium- to coarse-grained non-graphic albite-microcline-quartz pegmatites in close association with smoky quartz, Sc-bearing spessartine, Sc-bearing tusionite, and schorl. It often grows together with Sc-bearing tusionite and occurs as single columnar crystals ranging from 50 to 400 μm in length, as inclusions in spessartine and tourmaline, and rarely as crystals in blebs along boundaries between garnet, tourmaline, and quartz. Badakhshanite-(Y) is yellow brown and has a white streak and a vitreous luster. It is brittle, with a conchoidal fracture, Mohs hardness of 6.5–7, and calculated density of 4.41 g/cm. In thin section it is transparent and pale yellow, non-pleochroic, biaxial (–), with α = 1.805(2), βcalc = 1.827, γ = 1.835(3) (λ = 590 nm); 2V (meas.) = –60(10)°. Dispersion is weak, r &gt; v. Extinction is straight, elongation is negative. FTIR spectra show the absence of (OH) and H2O groups. Chemical analysis by electron microprobe using WDS (6 points), SIMS, and ICP-OES for B and Be gave SiO2 11.96, ThO2 0.12, Sm2O3 0.17, Gd2O3 0.30, Tb2O3 0.10, Dy2O3 0.73, Ho2O3 0.19, Er2O3 1.34, Tm2O3 0.54, Yb2O3 8.82, Lu2O3 2.32, Y2O3 16.60, Sc2O3 1.57, Al2O3 3.06, B2O3 22.06, FeO 0.94, MnO 23.33, CaO 0.58, BeO 2.84, total 97.57 wt.%.The empirical formula based on 24 O apfu is (Y1.21REE0.78Th0.01)Σ2(Mn3.47Y0.34Ca0.11Fe2+0.08)Σ4(Al0.63Sc0.24Fe2+0.06□0.07)Σ1[(Si2.10B6.69Be1.20)Σ9.99O24], where REE = (Yb0.47Lu0.12Dy0.04Er0.07Tm0.03 Ho0.01Gd0.02Sm0.01Tb0.01)Σ0.78. Badakhshanite-(Y) is orthorhombic, space group Pnma, a 12.852(1), b 4.5848(5), c 12.8539(8) Å, V 757.38(7) Å3, Z = 2. The crystal structure was refined to R1 = 4.31% based on 1431 unique [F &gt; 4σF] reflections. In the crystal structure of badakhshanite-(Y), a layer of tetrahedra parallel to (010) is composed of four different tetrahedrally coordinated sites: Si, B(1), B(2), and T (&lt;Si–O&gt; = 1.623 Å, &lt;B(1)–O&gt; = 1.485 Å, &lt;B(2)–O&gt; = 1.479 Å, &lt;T–O&gt; = 1.557 Å), which form four-, five-, and eight-membered rings, having the composition (Si2B7BeO24). Between the sheets of tetrahedra, there are three cation sites: M(1), M(2), and M(3) (&lt;M(1)–O&gt; = 2.346 Å, &lt;M(2)–O&gt; = 2.356 Å, &lt;M(3)–O&gt; = 2.016 Å) occupied by Y(REE), Mn2+(Y, Ca, Fe2+), and Al(Sc), respectively. The M(1,2) sites ideally give Y2Mn4apfu; the M(3) site ideally gives Al apfu. Badakhshanite-(Y) is an Al- and Be-analogue of perettiite-(Y).

The crystal structure of voggite, a new hydrated Na–Zr hydroxide–phosphate–carbonate mineral

1990 ◽  
Vol 54 (376) ◽  
pp. 495-500 ◽  
Author(s):  
Jan T. Szymański ◽  
Andrew C. Roberts
Keyword(s):  
Crystal Structure ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Bidentate Ligand ◽  
New Mineral ◽  
Chemical Formula ◽  
The Third ◽  
Carbonate Ion ◽  
Phosphate Carbonate

AbstractThe crystal structure of the new mineral voggite, Na2Zr(PO4)(CO3)(OH).2H2O , from the Francon quarry, Montreal, Quebec, Canada, has been solved in order to determine the correct chemical formula, as conventional electron microprobe methods were found unreliable. The unit cell is monoclinic, I2/m, with a = 12.261(2), b = 6.561(1), c = 11.757(2)Å, β = 116.19(2)°. The structure consists of layers of edge-sharing Zr-O pentagonal bipyramids, separated by layers of Na-(O,H2O) octahedra. The carbonate ion acts as a bidentate ligand in the Zr-O polyhedron, the third oxygen atom being bonded to the Na atom. The phosphate group is bonded to three different Zr atoms and to a Na atom. The Zr-O bond lengths vary from 2.067 to 2.283 (mean 2.140Å), while Na-O are between 2.304 and 2.773, (σ = 0.006Å, mean 2.480Å). The carbonate and phosphate bonds are normal. It is inferred from the structure that the columns of octahedrally coordinated Na atoms can easily be broken apart when subjected to the heat generated by the electron microprobe beam, with the subsequent expulsion of water. This gives rise to ‘mobile’ Na atoms, which make quantitative electron microprobe analysis extremely difficult. The structure allows the ‘liberated’ Na atoms to move freely within planes parallel to .

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