Natromarkeyite and pseudomarkeyite, two new calcium uranyl carbonate minerals from the Markey mine, San Juan County, Utah, USA

2020 ◽  
Vol 84 (5) ◽  
pp. 753-765 ◽  
Author(s):  
Anthony R. Kampf ◽  
Travis A. Olds ◽  
Jakub Plášil ◽  
Peter C. Burns ◽  
Joe Marty

AbstractThe new minerals natromarkeyite, Na2Ca8(UO2)4(CO3)13(H2O)24⋅3H2O (IMA2018-152) and pseudomarkeyite, Ca8(UO2)4(CO3)12(H2O)18⋅3H2O (IMA2018-114) were found in the Markey mine, San Juan County, Utah, USA, where they occur as secondary phases on asphaltum. Natromarkeyite properties are: untwinned blades and tablets to 0.2 mm, pale yellow green colour; transparent; white streak; bright bluish white fluorescence (405 nm laser); vitreous to pearly lustre; brittle; Mohs hardness 1½ to 2; irregular fracture; three cleavages ({001} perfect, {100} and {010} good); density = 2.70(2) g cm–3; biaxial (–) with α = 1.528(2), β = 1.532(2) and γ = 1.533(2); and pleochroism is X = pale green yellow, Y ≈ Z = light green yellow. Pseudomarkeyite properties are: twinned tapering blades and tablets to 1 mm; pale green yellow colour; transparent; white streak; bright bluish white fluorescence (405 nm laser); vitreous to pearly lustre; brittle; Mohs hardness ≈ 1; stepped fracture; three cleavages ({10$\bar{1}$} very easy, {010} good, {100} fair); density = 2.88(2) g cm–3; biaxial (–) with α = 1.549(2), β = 1.553(2) and γ = 1.557(2); and it is nonpleochroic. The Raman spectra of markeyite, natromarkeyite and pseudomarkeyite are very similar and exhibit bands consistent with UO22+, CO32– and O–H. Electron microprobe analyses provided the empirical formula Na2.01Ca7.97Mg0.03Cu2+0.05(UO2)4(CO3)13(H2O)24⋅3H2O (–0.11 H) for natromarkeyite and Ca7.95(UO2)4(CO3)12(H2O)18⋅3H2O (+0.10 H) for pseudomarkeyite. Natromarkeyite is orthorhombic, Pmmn, a = 17.8820(13), b = 18.3030(4), c = 10.2249(3) Å, V = 3336.6(3) Å3 and Z = 2. Pseudomarkeyite is monoclinic, P21/m, a = 17.531(3), b = 18.555(3), c = 9.130(3) Å, β = 103.95(3)°, V = 2882.3(13) Å3 and Z = 2. The structures of natromarkeyite (R1 = 0.0202 for 2898 I > 2σI) and pseudomarkeyite (R1 = 0.0787 for 2106 I > 2σI) contain uranyl tricarbonate clusters that are linked by (Ca/Na)–O polyhedra forming thick corrugated heteropolyhedral layers. Natromarkeyite is isostructural with markeyite; pseudomarkeyite has a very similar structure.

2018 ◽  
Vol 83 (03) ◽  
pp. 349-360 ◽  
Author(s):  
Anthony R. Kampf ◽  
Jakub Plášil ◽  
Anatoly V. Kasatkin ◽  
Barbara P. Nash ◽  
Joe Marty

AbstractMagnesioleydetite (IMA2017-063), Mg(UO2)(SO4)2·11H2O, and straβmannite (IMA2017-086), Al(UO2)(SO4)2F·16H2O, are two new minerals from mines in Red Canyon, San Juan County, Utah, USA. Magnesioleydetite occurs in the Markey mine and straβmannite occurs in both the Markey and Green Lizard mines. Both minerals are secondary phases found in efflorescent crusts on the surfaces of mine walls. Magnesioleydetite occurs in irregular aggregates (to ~0.5 mm) of blades (to ~0.2 mm) exhibiting the following properties: transparent to translucent; pale green–yellow colour; vitreous lustre; white streak; non-fluorescent; brittle; Mohs hardness ≈ 2; irregular fracture; one perfect cleavage on {001}; and calculated density = 2.463 g/cm3. Straβmannite occurs in irregular aggregates (to ~0.5 mm) of equant crystals (to ~0.2 mm) exhibiting the following properties: transparent; light yellow–green colour; vitreous to greasy lustre; nearly white streak; bright greenish-blue fluorescence; somewhat brittle, Mohs hardness ≈ 1½; irregular fracture; one good cleavage on {001}; measured and calculated densities of 2.20(2) and 2.173 g/cm3, respectively; optically biaxial (–); α = 1.477(2), β = 1.485(2) and γ = 1.489(2) (white light); 2Vmeas.= 72(2)°; dispersionr>v(slight); orientationY=b,X∧c= 20° (in obtuse β); pleochroism withX= nearly colourless,Y= pale green–yellow andZ= light green–yellow (X<Y<Z). The empirical formulas for magnesioleydetite and straβmannite are (Mg0.56Fe0.26Zn0.11Mn0.01)Σ0.94(U0.99O2)(S1.015O4)2·11H2O and Al1.00Na0.16(U0.99O2)(S1.00O4)2[F0.58(OH)0.42]·16H2O, respectively. Magnesioleydetite is monoclinic,C2/c,a= 11.3513(3),b= 7.7310(2),c= 21.7957(15) Å, β = 102.387(7)°,V= 1868.19(16) Å3andZ= 4. Straβmannite is monoclinic,C2/c,a= 11.0187(5),b= 8.3284(3),c= 26.6727(19) Å, β = 97.426(7)°,V= 2427.2(2) andZ= 4. The structures of magnesioleydetite (R1= 0.016 for 2040I> 2σIreflections) and straβmannite (R1= 0.0343 for 2220I> 2σIreflections) each contain uranyl-sulfate sheets based on the protasite-anion topology.


2019 ◽  
Vol 83 (6) ◽  
pp. 799-808 ◽  
Author(s):  
Anthony R. Kampf ◽  
Travis A. Olds ◽  
Jakub Plášil ◽  
Barbara P. Nash ◽  
Joe Marty

AbstractThe new mineral lussierite (IMA2018-101), Na10[(UO2)(SO4)4](SO4)2(H2O)3, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as pale green–yellow prisms or blades in a secondary assemblage with belakovskiite, ferrinatrite, halite, ivsite, metavoltine and thénardite. The streak is white and the fluorescence is bright cyan under 365 nm ultraviolet light. Crystals are transparent with vitreous lustre. The tenacity is brittle, the Mohs hardness is 2½, the fracture is irregular and no cleavage was observed. The mineral is easily soluble in H2O and has a measured density of 2.87(2) g cm–3. Lussierite is optically biaxial (+), with α = 1.493(1), β = 1.505(1) and γ = 1.518(1) (white light); 2Vmeas.= 88(1)°; dispersion isr>v, moderate; pleochroism:X= colourless,YandZ= green yellow (X<Y≈Z); optical orientation:X=b,Z∧a= 44° in obtuse β. Electron microprobe analyses (wavelength-dispersive spectroscopy mode) provided Na10(U0.99O2)(S1.00O4)6·3H2O (+0.06 H for charge balance). The five strongest X-ray powder diffraction lines are [dobsÅ(I)(hkl)]: 6.69(95)($\bar{1}$11,130), 4.814(100)(150,002,060), 3.461(83)(171,$\bar{2}$02), 2.955(81)(113,330) and 2.882(74)($\bar{1}$91,311,191,0·10·0). Lussierite is monoclinic,Cc,a= 9.3134(4),b= 28.7501(11),c= 9.6346(7) Å, β = 93.442(7)°,V= 2575.1(2) Å3andZ= 4. The structure (R1= 0.0298 for 5202I> 2σI) contains a [(UO2)(SO4)4]6–uranyl sulfate cluster in which one SO4tetrahedron shares an edge (bidentate linkage) with the UO7pentagonal bipyramid. The uranyl sulfate clusters occur in layers and are linked through a complex network of bonds involving Na+cations, isolated SO4tetrahedra and isolated H2O groups.


2018 ◽  
Vol 83 (02) ◽  
pp. 153-160 ◽  
Author(s):  
Anthony R. Kampf ◽  
Travis A. Olds ◽  
Jakub Plášil ◽  
Joe Marty ◽  
Samuel N. Perry

AbstractThe new mineral feynmanite, Na(UO2)(SO4)(OH)·3.5H2O, was found in both the Blue Lizard and Markey mines, San Juan County, Utah, USA, where it occurs as a secondary phase on pyrite-rich asphaltum in association with chinleite-(Y), gypsum, goethite, natrojarosite, natrozippeite, plášilite, shumwayite (Blue Lizard) and wetherillite (Markey). The mineral is pale greenish yellow with a white streak and fluoresces bright greenish white under a 405 nm laser. Crystals are transparent with a vitreous lustre. It is brittle, with a Mohs hardness of ~2, irregular fracture and one perfect cleavage on {010}. The calculated density is 3.324 g cm–3. Crystals are thin needles or blades, flattened on {010} and elongate on [100], exhibiting the forms {010}, {001}, {101} and {10$\bar{1}$}, and are up to ~0.1 mm in length. Feynmanite is optically biaxial (–), with α = 1.534(2), β = 1.561(2) and γ = 1.571(2) (white light); 2Vmeas.= 62(2)°; no dispersion; and optical orientation:X=b,Y≈a,Z≈c. It is weakly pleochroic:X= colourless,Y= very pale green yellow andZ= pale green yellow (X&lt;Y&lt;Z). Electron microprobe analyses (WDS mode) provided (Na0.84Fe0.01)(U1.01O2)(S1.01O4)(OH)·3.5H2O. The five strongest powder X-ray diffraction lines are [dobsÅ(I)(hkl)]: 8.37(100)(010), 6.37(33)($\bar{1}$01,101), 5.07(27)($\bar{1}$11,111), 4.053(46)(004,021) and 3.578(34)(120). Feynmanite is monoclinic, has space groupP2/n,a= 6.927(3),b= 8.355(4),c= 16.210(7) Å, β = 90.543(4)°,V= 938.1(7) Å3andZ= 4. The structure of feynmanite (R1= 0.0371 for 1879Io&gt; 2σI) contains edge-sharing pairs of pentagonal bipyramids that are linked by sharing corners with SO4groups, yielding a [(UO2)2(SO4)2(OH)2]2–sheet based on the phosphuranylite anion topology. The sheet is topologically identical to those in deliensite, johannite and plášilite. The dehydration of feynmanite to plášilite results in interlayer collapse involving geometric reconfiguration of the sheets and the ordering of Na.


2018 ◽  
Vol 82 (5) ◽  
pp. 1089-1100 ◽  
Author(s):  
Anthony R. Kampf ◽  
Jakub Plášil ◽  
Anatoly V. Kasatkin ◽  
Joe Marty ◽  
Jiří Čejka

ABSTRACTThe new mineral markeyite (IMA2016-090), Ca9(UO2)4(CO3)13·28H2O, was found in the Markey mine, San Juan County, Utah, USA, where it occurs as a secondary phase on asphaltum in association with calcite, gypsum and natrozippeite. The mineral is pale yellowish-green with white streak and fluoresces bright bluish white under a 405 nm laser. Crystals are transparent and have vitreous to pearly lustre. It is brittle, with Mohs hardness 1½ to 2, irregular fracture and three cleavages: perfect on {001}; good on {100} and {010}. The measured density is 2.68 g cm–3. Crystals are blades, flattened on {001} and elongate on [010], exhibiting the forms {100}, {010}, {001}, {110}, {101}, {011} and {111}. Markeyite is optically biaxial (–) with α = 1.538(2), β = 1.542(2) and γ = 1.545(2) (white light); the measured 2V is 81(2)°; the dispersion isr<v(weak); the optical orientation isX=c,Y=b,Z=a; and pleochroism isX= light greenish yellow,YandZ= light yellow (X>Y≈Z). Electron microprobe analyses (energy-dispersive spectroscopy mode) yielded CaO 18.60, UO342.90, CO221.30 (calc.) and H2O 18.78 (calc.), total 101.58 wt.% and the empirical formula Ca8.91(U1.01O2)4(CO3)13·28H2O. The six strongest powder X-ray diffraction lines are [dobsÅ(I)(hkl)]: 10.12(69)(001), 6.41(91)(220,121), 5.43(100)(221), 5.07(33)(301,002,131), 4.104(37)(401,141) and 3.984(34)(222). Markeyite is orthorhombic,Pmmn,a= 17.9688(13),b= 18.4705(6),c= 10.1136(4) Å,V= 3356.6(3) Å3andZ= 2. The structure of markeyite (R1= 0.0435 for 3427Fo> 4σF) contains uranyl tricarbonate clusters (UTC) that are linked by Ca–O polyhedra forming thick corrugated heteropolyhedral layers. Included within the layers is an additional disordered CO3group linking the Ca–O polyhedra. The layers are linked to one another and to interlayer H2O groups only via hydrogen bonds. The structure bears some similarities to that of liebigite.


2013 ◽  
Vol 77 (3) ◽  
pp. 367-383 ◽  
Author(s):  
A. V. Kasatkin ◽  
F. Nestola ◽  
J. Plášil ◽  
J. Marty ◽  
D. I. Belakovskiy ◽  
...  

AbstractTwo new minerals – manganoblödite (IMA2012–029), ideally Na2Mn(SO4)2·4H2O, and cobaltoblödite (IMA2012–059), ideally Na2Co(SO4)2·4H2O, the Mn-dominant and Co-dominant analogues of blödite, respectively, were found at the Blue Lizard mine, San Juan County, Utah, USA. They are closely associated with blödite (Mn-Co-Ni-bearing), chalcanthite, gypsum, sideronatrite, johannite, quartz and feldspar. Both new minerals occur as aggregates of anhedral grains up to 60 μm (manganoblödite) and 200 μm (cobaltoblödite) forming thin crusts covering areas up to 2 × 2 cm on the surface of other sulfates. Both new species often occur as intimate intergrowths with each other and also with Mn-Co-Ni-bearing blödite. Manganoblödite and cobaltoblödite are transparent, colourless in single grains and reddish-pink in aggregates and crusts, with a white streak and vitreous lustre. Their Mohs' hardness is ∼2½. They are brittle, have uneven fracture and no obvious parting or cleavage. The measured and calculated densities are Dmeas = 2.25(2) g cm−3 and Dcalc = 2.338 g cm−3 for manganoblödite and Dmeas = 2.29(2) g cm−3 and Dcalc = 2.347 g cm−3 for cobaltoblödite. Optically both species are biaxial negative. The mean refractive indices are α = 1.493(2), β = 1.498(2) and γ = 1.501(2) for manganoblödite and α = 1.498(2), β = 1.503(2) and γ = 1.505(2) for cobaltoblödite. The chemical composition of manganoblödite (wt.%, electron-microprobe data) is: Na2O 16.94, MgO 3.29, MnO 8.80, CoO 2.96, NiO 1.34, SO3 45.39, H2O (calc.) 20.14, total 98.86. The empirical formula, calculated on the basis of 12 O a.p.f.u., is: Na1.96(Mn0.44Mg0.29Co0.14Ni0.06)Σ0.93S2.03O8·4H2O. The chemical composition of cobaltoblödite (wt.%, electron-microprobe data) is: Na2O 17.00, MgO 3.42, MnO 3.38, CoO 7.52, NiO 2.53, SO3 45.41, H2O (calc.) 20.20, total 99.46. The empirical formula, calculated on the basis of 12 O a.p.f.u., is: Na1.96(Co0.36Mg0.30Mn0.17Ni0.12)Σ 0.95S2.02O8·4H2O. Both minerals are monoclinic, space group P21/a, with a = 11.137(2), b = 8.279(1), c = 5.5381(9) Å, β = 100.42(1)°, V = 502.20(14) Å3 and Z = 2 (manganoblödite); and a = 11.147(1), b = 8.268(1), C = 5.5396(7) Å, β = 100.517(11)°, V = 501.97(10) Å3 and Z = 2 (cobaltoblödite). The strongest diffractions from X-ray powder pattern [listed as (d,Å(I)(hkl)] are for manganoblödite: 4.556(70)(210, 011); 4.266(45)(01); 3.791(26)(11); 3.338(21)(310); 3.291(100)(220, 021), 3.256(67)(211, 21), 2.968(22)(21), 2.647(24)(01); for cobaltoblödite: 4.551(80)(210, 011); 4.269(50)(01); 3.795(18)(11); 3.339(43)(310); 3.29(100)(220, 021), 3.258(58)(11, 21), 2.644(21)(01), 2.296(22)(122). The crystal structures of both minerals were refined by single-crystal X-ray diffraction to R1 = 0.0459 (manganoblödite) and R1 = 0.0339 (cobaltoblödite).


2017 ◽  
Vol 81 (4) ◽  
pp. 753-779 ◽  
Author(s):  
Anthony R. Kampf ◽  
Jakub Plášil ◽  
Anatoly V. Kasatkin ◽  
Joe Marty ◽  
Jiří Čejka

AbstractThe new minerals klaprothite (IMA2015-087), Na6(UO2)(SO4)4(H2O)4, péligotite (IMA2015-088), Na6(UO2)(SO4)4(H2O)4and ottohahnite (IMA2015-098),Na6(UO2)2(SO4)5(H2O)7·1.5H2O, were found in the Blue Lizard mine, San Juan County, Utah, USA, where they occur together as secondary phases. All three minerals occur as yellowish-green to greenish-yellow crystals, are brittle with irregular fracture, have Mohs hardness of ∼2½ and exhibit bright bluish-green fluorescence, and all are easily soluble in room temperature H2O. Only klaprothite exhibits cleavage; perfect on {100} and {001}. Quantitative energydispersive spectroscopy analyses yielded the empirical formulas Na6.01(U1.03O2)(S0.993O4)4(H2O)4, Na5.82(U1.02O2)(S1.003O4)4(H2O)4and Na5.88(U0.99O2)2(S1.008O4)5(H2O)8.5for klaprothite, péligotite and ottohahnite, respectively. Their Raman spectra exhibit similar features. Klaprothite is monoclinic,P21/c,a= 9.8271(4),b= 9.7452(3),c= 20.8725(15) Å, β = 98.743(7)°,V= 1975.66(17)Å3andZ= 4. Péligotite is triclinic,P1̄,a= 9.81511(18),b= 9.9575(2),c= 10.6289(8) Å, α = 88.680(6)°, β = 73.990(5)°, γ = 89.205(6)°,V= 998.22(8) Å3andZ=2. Ottohahnite is triclinic,P1̄,a= 9.97562(19),b= 11.6741(2),c= 14.2903(10) Å, α = 113.518(8)°, β = 104.282(7)°, γ = 91.400(6)°,V= 1464.59(14) Å3andZ= 2. The structures of klaprothite(R1= 2.22%) and péligotite (R1= 2.28%) both contain [(UO2)(SO4)4]6–clusters in which one SO4group has a bidentate linkage with the UO7polyhedron; Na–O polyhedra linkclusters into thick heteropolyhedral layers and link layers into frameworks; the structures differ in the configuration of Na–O polyhedra that link the layers. The structure of ottohahnite (R1= 2.65%) contains [(UO2)4(SO4)10]12–clusters in which each UO7polyhedron has a bidentate linkage with one SO4group; Na–O polyhedra link clusters into a thin heteropolyhedral slice and also link the slices into a framework. The minerals are named for Martin Heinrich Klaproth (1743–1817), Eugène-MelchiorPéligot (1811–1890) and Otto Hahn (1879–1968).


2020 ◽  
Vol 84 (3) ◽  
pp. 435-443
Author(s):  
Anthony R. Kampf ◽  
Travis A. Olds ◽  
Jakub Plášil ◽  
Barbara P. Nash ◽  
Joe Marty

AbstractThe new mineral pseudomeisserite-(NH4) (IMA2018-166), (NH4,K)2Na4[(UO2)2(SO4)5]⋅4H2O, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as light yellow prisms in a secondary assemblage with belakovskiite, blödite, changoite, ferrinatrite, gypsum, ivsite, metavoltine and tamarugite. The streak is very pale yellow and the fluorescence is bright lime green under 405 nm ultraviolet light. Crystals are transparent with vitreous lustre. The tenacity is brittle, the Mohs hardness is 2½, the fracture is curved or conchoidal and there is one perfect cleavage on {100}. The mineral is easily soluble in H2O and has a measured density of 3.22(2) g⋅cm–3. Pseudomeisserite-(NH4) is optically biaxial (–) with α = 1.536(2), β = 1.559(2) and γ = 1.565(2) (white light); 2Vmeas. = 53(1)°; dispersion is r > v, distinct; pleochroism: X colourless, Y light yellow and Z pale yellow (X < Z < Y); optical orientation: Z = b, Y ∧ c = 33° in obtuse β). Electron microprobe analyses (WDS mode) provided (NH4)1.49K0.60Na3.87U2.00S5.04O28H7.78. The five strongest X-ray powder diffraction lines are [dobs, Å(I)(hkl)]: 12.69(76)(100), 6.83(84)(012,102), 6.01(100)($\bar{2}$02), 3.959(67)($\bar{2}$21,$\bar{2}$14,$\bar{1}$23) and 3.135(76)($\bar{2}$06,223,$\bar{1}$16). Pseudomeisserite-(NH4) is monoclinic, P21/c, a = 13.1010(3), b = 10.0948(2), c = 19.4945(14) Å, β = 104.285(7)°, V = 2498.5(2) Å3 and Z = 4. The structural unit in the structure (R1 = 0.0254 for 3837 I > 2σI reflections) is a novel [(UO2)2(SO4)5]6– uranyl-sulfate band.


2006 ◽  
Vol 70 (3) ◽  
pp. 329-340 ◽  
Author(s):  
W. Krause ◽  
H.-J. Bernhardt ◽  
R.S.W. Braithwaite ◽  
U. Kolitsch ◽  
R. Pritchard

AbstractKapellasite, Cu3Zn(OH)6Cl2, is a new secondary mineral from the Sounion No. 19 mine, Kamariza, Lavrion, Greece. It is a polymorph of herbertsmithite. Kapellasite forms crusts and small aggregates up to 0.5 mm, composed of bladed or needle-like indistinct crystals up to 0.2 mm long. The colour is green-blue, the streak is light green-blue. There is a good cleavage parallel to ﹛0001﹜. Kapellasite is uniaxial negative, ω = 1.80(1), ε = 1.76(1); pleochroism is distinct, with E = pale green, O = green-blue. Dmeas = 3.55(10) g/cm3; Dcalc. = 3.62 g/cm3. Electron microprobe analyses of the type material gave CuO 58.86, ZnO 13.92, NiO 0.03, CoO 0.03, Fe2O3 0.04, Cl 16.70, H2O (calc.) 12.22, total 101.80, less O = Cl 3.77, total 98.03 wt.%. The empirical formula is (Cu3.24Zn0.75)Σ3.99(OH)5.94Cl2.06, based on 8 anions. The five strongest XRD lines are [d in Å (I/I0, hkl)] 5.730 (100, 001), 2.865 (11, 002), 2.730 (4, 200), 2.464 (9, 021/201), 1.976 (5, 022/202). Kapellasite is trigonal, space group Pml, unit-cell parameters (from single-crystal data) a = 6.300(1), c = 5.733(1) Å, V= 197.06(6) Å3, Z = 1. The crystal structure of kapellasite is based on brucite-like sheets parallel to (0001), built from edge-sharing distorted M(OH,Cl)6 (M = Cu, Zn) octahedra. The sheets stack directly on each other (…AAA… stacking). Bonding between adjacent sheets is only due to weak hydrogen and O…C1 bonds. The name is in honour of Christo Kapellas (1938–2004), collector and mineral dealer from Kamariza, Lavrion, Greece.


2017 ◽  
Vol 81 (2) ◽  
pp. 273-285 ◽  
Author(s):  
Anthony R. Kampf ◽  
Jakub Plášil ◽  
Anatoly V. Kasatkin ◽  
Joe Marty ◽  
Jiří Čejka ◽  
...  

AbstractThe new mineral shumwayite (IMA2015-058), [(UO2)(SO4)(H2O)2]2·H2O, was found in the Green Lizard and Giveaway-Simplot mines, White Canyon district, San Juan County, Utah, USA, where it occurs as a secondary alteration phase. At the Green Lizard mine, it is found in association with calcite, gypsum, plášilite, pyrite, rozenite and sulfur; at the Giveaway-Simplot mine, shumwayite is associated with rhomboclase and römerite. The mineral occurs as pale greenish-yellow monoclinic prisms, elongated on [100], up to ∼0.3 mm long and commonly in subparallel to random intergrowths. The mineral is transparent with a vitreous lustre and has a white streak. It fluoresces bright greenish white under both longwave and shortwave ultraviolet radiation. The Mohs hardness is ∼2. Crystals are brittle with perfect {011} cleavage and irregular fracture. The mineral is slightly deliquescent and is easily soluble in room temperature H2O. The calculated density is 3.844 g cm–3. Optically, shumwayite is biaxial (+/–), with α = 1.581(1), β= 1.588(1), γ = 1.595(1) (measured in white light). The measured 2Vxbased on extinction data collected on a spindle stage is 89.8(8)°; the calculated 2Vxis 89.6°. Dispersion is strong, but the sense is not defined because the optic sign is ambiguous. No pleochroism was observed. The optical orientation isX=b,Y=c,Z=a. Energy-dispersive spectrometer analyses (with H2O based on the crystal structure) yielded the empirical formula U2.01S1.99O12.00·5H2O.Shumwayite is monoclinic,P21/c,a= 6.74747(15),b= 12.5026(3),c= 16.9032(12) Å, β = 90.919(6)°,V= 1425.79(11) Å3andZ= 4. The crystal structure (R1= 1.88% for 2936F> 4σF) contains UO7pentagonal bipyramids and SO4tetrahedra that link by corner-sharing to form [(UO2)(SO4)(H2O)2] chains along [100]. The chains and isolated H2O groups between them are linked together only by hydrogen bonds. The mineral is named in honour of the Shumway family, whose members account for the discovery and mining of hundreds of uranium deposits on the Colorado Plateau, including the Green Lizard mine.


2019 ◽  
Vol 84 (2) ◽  
pp. 267-273
Author(s):  
Anthony R. Kampf ◽  
Barbara P. Nash ◽  
Arturo A. Molina Donoso

AbstractThe new mineral mauriziodiniite (IMA2019-036), NH4(As2O3)2I, was found at the Torrecillas mine, Iquique Province, Chile, where it is a secondary alteration phase associated with calcite, cuatrocapaite-(NH4), lavendulan, magnesiokoritnigite and torrecillasite on matrix consisting of native arsenic, arsenolite and pyrite. Mauriziodiniite occurs as hexagonal tablets up to ~300 μm in diameter. Crystals are colourless and transparent, with pearly to adamantine lustre and white streak. The Mohs hardness is ~1. Tablets are sectile and easily flexible, but not elastic. Fracture is curved, irregular and stepped. Cleavage is perfect on {001}. The calculated density is 3.916 g/cm3. Optically, mauriziodiniite is uniaxial (–) with ω = 2.07(calc) and ɛ = 1.770(5) (white light). The empirical formula, determined from electron microprobe analyses, is (NH4)0.94K0.03(As2O3)2I0.92Cl0.03. Mauriziodiniite is hexagonal, P6/mmm, a = 5.289(2), c = 9.317(2) Å, V = 225.68(18) Å3 and Z = 1. The structure, refined to R1 = 4.16% for 135 Io > 2σI reflections, contains three types of layers: (1) a planar neutral As2O3 (arsenite) sheet; (2) an NH4+ layer that links adjacent arsenite sheets via bonds to their O atoms; and (3) an I– layer that links adjacent arsenite sheets via bonds to their As atoms. The layer sequence is I–As2O3–NH4–As2O3–I. Mauriziodiniite is isostructural with lucabindiite and is structurally related to gajardoite, cuatrocapaite-(NH4), cuatrocapaite-(K) and torrecillasite.


Sign in / Sign up

Export Citation Format

Share Document