ALBERT

Description: Rakovanite, Na3{H3[V10O28]}{middle dot}15H2O, is a new mineral species from the Sunday and the West Sunday mines, Slick Rock district, San Miguel County, Colorado, USA; the mineral is the natural analog of the previously synthesized phase. Rakovanite is orange, with an orange-yellow streak. Crystals of rakovanite are up to 1 mm in maximum dimension and vary in habit from blocky to prismatic on [100]. The mineral is transparent, with a subadamantine luster; it does not fluoresce in long- or short-wave ultraviolet radiation. Rakovanite displays brittle tenacity, and has a Mohs hardness of 1. No cleavage or parting was observed, and the mineral displays a conchoidal fracture. The density calculated from the ideal formula and the single-crystal cell data is 2.407 g cm-3. Rakovanite is biaxial (+), with {alpha}589nm = 1.776(5), {beta}589nm = 1.803(5), {gamma}589nm = 1.910(6). The measured values of 2V are: 2Vz540nm = 58(1); 2Vz589nm = 56(1); 2Vz650nm = 53(1){degrees}. Dispersion is r 〈 v, strong, parallel; orientation: X = b; Z / c = 8{degrees} in obtuse {beta}. The pleochroic scheme in rakovanite is: X light yellow, Y orangish yellow, Z yellowish orange, Z 〉 Y 〉 X. Its chemical composition was obtained by electron-probe microanalysis and the crystal-structure refinement; the empirical formula (V = 10 apfu) is (Na2.90K0.07Ca0.01Al0.01){sum}2.99{H2.98[V10O28]}{middle dot}15H2O, and the simplified formula is Na3{H3[V10O28]}{middle dot}15H2O. Rakovanite is monoclinic, space group P21/n, with a 12.0248(17), b 17.121(3), c 18.140(3) A, {beta} 106.242(8){degrees}, and Z = 4; the strongest four lines in the powder-diffraction pattern [d in A(I)(hkl)] are: 11.270(100)([IMG]f1.gif" ALT="Formula" BORDER="0"〉01), 7.696(81)(021), 8.709(78)(002), and 6.892(63)(120). The atomic arrangement of rakovanite has been refined to R1 = 0.0383; the structural unit in the phase is formed of a triply-protonated decavanadate polyanion, {H3[V10O28]}. The structural units are linked by the interstitial complexes, the (Na3{middle dot}15H2O) contents of which balance the +3 charges of the decavanadate polyanion with a NaO4(H2O)2 group, a Na2(H2O)10 dimer, and three H2O molecules that do not bond to the interstitial cations.

Description: Postite, Mg(H2O)6Al2(OH)2(H2O)8(V10O28)·13H2O, is a new mineral species from the Vanadium Queen mine, La Sal Creek Canyon, and the Blue Cap mine, Lyon Canyon Creek, San Juan County, Utah, U.S.A. Postite occurs as very thin, needle-like prisms with pyramidal terminations; crystals commonly occur in parallel bundles and grow in divergent and “jackstraw” masses. Individual crystals are up to 1 mm long and 50 μm in diameter, and are golden-yellow with a yellow streak. The mineral is transparent, with a subadamantine luster; it does not fluoresce in short- or long-wave ultraviolet radiation. Postite has a Mohs hardness of approximately 2 and brittle tenacity. The mineral has one good cleavage on {001} and at least two perfect cleavages parallel to [001], possibly {100} and {010}. The fracture is splintery. The density calculated from the empirical formula using the single-crystal cell data is 2.226 g/cm3. Postite is biaxial (+) with a 2V angle of 71º. Indices of refraction for postite are α 1.727(3), β 1.733(3), and γ1.745(3). The optical orientation is X = c, Y = b, Z = a. Dispersion was not observed and pleochroism was not perceptible. Electron probe microanalysis and the crystal structure solution gave the empirical formula (Mg0.97Na0.06Ca0.04Sr0.01K0.01)∑1.09Al1.94 [(OH)1.92(H2O)0.08]‡”2.00 (V10O28)·27H2O. The simplified structural formula of postite is Mg(H2O)6Al2(OH)2(H2O)8(V10O28) ·13H2O. Postite is orthorhombic, Pccn, with a 16.3357(6), b 24.2434(17), c 11.7343(4) Å, V 4647.2(4) Å3, and Z = 4. The strongest four lines in the diffraction pattern are [d in Å(I)(hkl)]: 8.937(100)(111), 12.190(90)(020), 3.771(24)(113), and 8.248(22)(200). The atomic arrangement of postite was solved and refined to R1 = 0.0358. The structural unit is a decavanadate polyanion, [V10O28]6−; charge balance in the structure is maintained by the [Mg(H2O)6Al2(OH)2(H2O)8 ·13 H2O]6+ interstitial unit. The interstitial unit consists of a [Mg(H2O)6]2+ monomer, an [Al2(OH)2(H2O)8]4+ edge-sharing dimer, and thirteen additional H2O molecules. The linkage between the structural unit and the interstitial unit results from hydrogen bonding between oxygen atoms of the structural unit with hydrogen atoms of the [Al2(OH)2(H2O)8]4+ edge-sharing dimer and those of isolated H2O molecules. The new mineral is named in honor of Dr. Jeffrey E. Post (b. 1954), Curator-in-Charge of the National Gem and Mineral Collection, U. S. National Museum of Natural History (Smithsonian Institution).

Description: Gunterite, Na4(H2O)16(H2V10O28)·6H2O, is a new mineral species from the West Sunday mine, Slick Rock district, San Miguel County, Colorado, U.S.A. Crystals of gunterite are tabular on {001} and generally stacked into elongate curved multiple crystals up to 0.5 mm in maximum dimension; the crystals are orange-yellow, with a yellow streak. The mineral displays a subadamantine luster, and is transparent; it does not fluoresce in short- or long-range ultraviolet radiation. Gunterite has a hardness of about 1, a brittle tenacity, and an irregular fracture; no cleavage or parting was observed. The density calculated from the empirical formula using the single-crystal cell data is 2.398 g cm-3. Gunterite is biaxial (+), with a 1.735(5), ß 1.770(5) and ? 1.825(5); 2V is equal to 78° (white light). The dispersion v 〈 r is strong and parallel. Optical orientation; X = b, Y ˜ c; pleochroism: X yellow, Y orange, Z yellow; Y 〉 X 〉 Z. Gunterite is soluble in water at room temperature. Electronprobe microanalysis and the crystal-structure solution provided the empirical formula (V + Al = 10 apfu): (Na3.20K0.02Ca0.87)?4.09[H1.06(V9.99Al0.01)?10O28]·22H2O. The simplified formula of gunterite is Na4(H2O)16(H2V10O28)·6H2O. There is extensive substitution of Ca for Na in gunterite, yielding a structural formula of (Na4-xCax)?4.00(H2O)16(H2-xV10O28)·6H2O; the average value of x from the chemical analyses is 0.85. Gunterite is monoclinic, C2/m, with a 19.848(2), b 10.1889(11), c 13.1184(15) Å, ß 130.187(9)°, V 2026.6(4) Å3, and Z = 2. The strongest four lines in the diffraction pattern [d in Å(I)hkl] are: 10.01(100)2¯01,001, 8.44(72)110, 8.09(46)1¯11, and 2.997(29)3¯31,401. The atomic arrangement of gunterite was refined to R1 = 0.0632. The structural unit is a doubly-protonated decavanadate polyanion, {H2[V10O28]}. The interstitial units linking the structural units contain two Na polyhedra; the Na2 polyhedron is split into two partially occupied sites that are 0.76 Å apart, and significant Ca occupies that site. Several of the H2O molecules in the interstitial complex are disordered. The mineral is named in honor of Mickey E. Gunter, Professor of Mineralogy at the University of Idaho.

Description: We report on the discovery, description and solution of the structure of a new member of the pascoite family of minerals, hughesite, from the Sunday mine, Gypsum Valley, San Miguel County, Slick Rock District, Colorado, USA (38°4’19” N, 108°48’15” W). Orange to golden orange crystals of hughesite occur in efflorescent crusts, averaging 2 mm thick, on the sandstone walls of mine workings and in rock fractures. Hughesite forms through the oxidation of corvusite, (Na,Ca,K)1–x (V5+,V4+,Fe2+)8O28•4H2O, and montrosite, (V3+,Fe2+,V4+)O(OH), the primary vanadium oxide phases present, as they react with acidic, oxidizing groundwater. Crystals vary in habit, including blocky, spear-shaped, and platy, with one good cleavage on (001). Crystals are transparent to translucent with a subadamantine luster, and upon partial dehydration, they become opaque. Hughesite is biaxial (–), with a 1.698(5), ß 1.740(5), ? 1.770(5), and the measured 2V589nm is 84(2)°. It exhibits a strong r 〉 v dispersion, and is pleochroic with X = Y light golden yellow, and Z dark golden yellow. Its absorption is characterized by Z 〉 Y = X. Electron-probe microanalysis and the crystal-structure solution provided the empirical formula Na2.99Al1.05(V10O28)•22 H2O (based upon V = 10 apfu). The ideal formula of hughesite is Na3AlV10O28•22H2O. The density calculated from the empirical formula using the single-crystal cell data is 2.29 g/cm3. Hughesite is triclinic, space group P1¯, with a 8.668(4), b 10.295(4), c 12.908(5), a 105.826(9), ß 97.899(9), ? 103.385(9)°, V 1053.0(8) Å3, and Z = 1. The strongest four lines in the powder-diffraction pattern [d in Å(I)hkl]: are 12.24(100)001¯, 8.25(38)100, 9.50(30)01¯0, and 8.99(28)01¯1. The crystal structure, refined to R1 = 0.0496, consists of two components, the structural unit, which contains the decavanadate (V10O28)6- polyanion, and the fully hydrated interstitial complex, composed of two separate components, a Na3(OH2)12O2 trimer with two distinct cation sites, and a Al(OH2)6 monomer.

Description: Wernerbaurite, {[Ca(H 2 O) 7 ] 2 (H 2 O) 2 (H 3 O) 2 }{V 10 O 28 }, and schindlerite, {[Na 2 (H 2 O) 10 ](H 3 O) 4 }{V 10 O 28 }, are new mineral species from the St. Jude mine, Slick Rock district, San Miguel County, Colorado, U.S.A. Crystals of wernerbaurite are tabular on {100} with stepped faces and square to octagonal outlines, up to about 1 mm in maximum dimension; the crystals are yellow-orange and the streak is yellow. The mineral displays a subadamantine luster, and is transparent; it does not fluoresce in short- or long-wave ultraviolet radiation. Wernerbaurite has a hardness of about 2, a brittle tenacity, and irregular fracture; two good cleavages, {100} and {010}, were observed. The density calculated from the empirical formula using the single-crystal cell data is 2.352 g cm –3 . Wernerbaurite is biaxial (–), with α 1.745(3), β 1.780(3), and 1.795(3); 2 V 66(2)° (white light). Dispersion is r 〉 v , very strong. Optical orientation: X ^ a = 29°, Y ^ c = 44°, Z ^ b = 46°; pleochroism: X, Z = yellow, Y = orange; X = Z 〈 Y . Electron probe microanalysis and the crystal structure solution provided the empirical formula {(Ca 1.88 Na 0.14 K 0.03 Sr 0.02 ) 2.07 (H 2 O) 15.95 (H 3 O) 2.05 }{V 10 O 28 } (based on V 5+ = 10 and O = 46). The simplified structural formula of wernerbaurite is {[Ca(H 2 O) 7 ] 2 (H 2 O) 2 (H 3 O) 2 }{V 10 O 28 }. Wernerbaurite is triclinic, P , with a 9.7212(6), b 10.2598(8), c 10.5928(8) Å, α 89.999(6)°, β 77.083(7)°, 69.887(8)°, V 963.55(12) Å 3 , and Z = 1. The strongest four lines in the diffraction pattern [ d in Å(I)( hkl )] are: 10.32(100)(001), 8.88(95)(100), 9.64(92)(010), and 6.881(70)(111). The atomic arrangement of wernerbaurite was refined to R 1 = 0.0341 on the basis of 3,440 diffractions with F o 〉 4 F . The structural unit is a decavanadate polyanion, (V 10 O 28 ) 6– . The interstitial unit linking the structural units has a composition of {[Ca(H 2 O) 7 ] 2 (H 2 O) 2 (H 3 O) 2 } 6+ , and is formed of an isolated [Ca(H 2 O) 7 ] 2+ polyhedron, a (H 3 O) + ion, and an isolated H 2 O molecule. Wernerbaurite is named in honor of Prof. Dr. rer. nat. Werner H. Baur for his long, productive and distinguished career in mineralogical crystallography. Crystals of schindlerite are tabular and commonly occur in stacked parallel intergrowths up to 0.3 mm in maximum dimension; the crystals are orange with a yellow streak. Schindlerite displays a subadamantine luster, and is transparent; it does not fluoresce in short- or long-wave ultraviolet radiation. Schindlerite has a hardness of about 2, a brittle tenacity, and one good cleavage on {010}. The density calculated from the empirical formula using the single-crystal cell data is 2.461 g cm –3 . Schindlerite is biaxial (+), with α 1.74 (est), β 1.790(5), and 1.875 (calc); 2 V (meas) = 78.1° (white light). Dispersion is r 〉 v , very strong. The optical orientation is X ^ b = 25°, Y ^ c = 12°, Z ^ a = 3°. No pleochroism was perceptible. Electron probe microanalysis and the crystal structure solution provided the empirical formula {[(Na 1.58 K 0.35 Ca 0.02 Sr 0.01 ) 1. 96 (H 2 O) 10.00 ] (H 3 O) 4 }{V 10 O 28 } (based on V 5+ = 10 and O = 42 ). The simplified structural formula of schindlerite is {[Na 2 (H 2 O) 10 ](H 3 O) 4 }{V 10 O 28 }. Schindlerite is triclinic, P , with a 8.5143(3), b 10.4283(5), c 11.2827(8) Å, α 68.595(5)°, β 87.253(6)°, 67.112(5)°, V 854.08(8) Å 3 , and Z = 1. The strongest four lines in the diffraction pattern [ d in Å(I)( hkl )] are: 8.68(100)(010, 011), 10.51(94)(001), 7.70(86)(100,110), and 6.73(61)(111,01). The atomic arrangement of schindlerite was refined to R 1 = 0.0399. The structural unit is a decavanadate polyanion, (V 10 O 28 ) 6– . The interstitial unit linking the structural units has a composition of {[Na 2 (H 2 O) 10 ](H 3 O) 4 } 6+ , and is formed of a [Na 2 (H 2 O) 10 ] dimer decorated with four hydronium ions. As in wernerbaurite, an extensive network of hydrogen bonding links the interstitial unit to the structural unit in schindlerite. Schindlerite is named in honor of Dr. Michael Schindler, Associate Professor for Environmental Mineralogy at Laurentian University, Sudbury, Ontario, who has contributed greatly to our understanding of vanadium mineralogy. Wernerbaurite and schindlerite are the first hydronium-bearing decavanadate minerals, and both minerals are natural analogs of previously described synthetic phases.

Description: Hydropascoite, Ca 3 (V 10 O 28 )·24H 2 O, is a new mineral species (IMA2016-032) discovered in the Packrat mine, near Gateway, Mesa County, Colorado. It occurs as blades up to 2 mm in length on asphaltum associated with montroseite- and corvusite-bearing sandstone. Hydropascoite is dark yellow green, with a pistachio green streak, vitreous luster, Mohs hardness of ca . 11/2, brittle tenacity, irregular fracture, and one perfect cleavage on {001}. Density (meas.) is 2.38(2) g/cm 3 . Hydropascoite is biaxial (–), with α 1.730(5), β 1.780(5), 1.790(5) (white light); 2 V (meas.) = 54.1(6)°, and extreme dispersion. The optical orientation is X ^ a 10°, Z ^ c* 20°. Hydropascoite is pleochroic, with X = bluish green, Y = orange, Z = yellowish green; X 〉 Z 〉 Y . Electron probe microanalysis gave the empirical formula (Ca 2.69 Na 0.30 ) 2.99 (H 0.31 V 5+ 10 O 28 )·24H 2 O, based on O = 52. Hydropascoite is triclinic, , a 10.08700(19), b 11.0708(2), c 21.8112(15) Å, α 94.112(7)°, β 96.053(7)°, 116.398(8)°, V 2150.2(2) Å 3 , and Z = 2. The strongest four lines in the diffraction pattern are [ d in Å( I )( hkl )]: 8.92(100)( ), 10.70(31)(002), 9.77(28)(010), and 7.4539(22)( ). The atomic arrangement of hydropascoite was solved and refined to R 1 = 0.0488 for 8187 independent reflections with F 〉 4 F . The structural unit in hydropascoite is the [V 10 O 28 ] 6– decavanadate group; charge balance in the structure is maintained by the [Ca 3 ·24H 2 O] 6+ interstitial complex. The three Ca polyhedra in the interstitial complex are not polymerized. Linkage between the structural unit and the components of the interstitial complex is principally by hydrogen bonding. In addition to the extensive hydrogen bonding, three oxygen atoms of the structural unit bond directly to calcium atoms of the interstitial complex. The mineral is named to recognize its chemical and structural similarity to pascoite, Ca 3 (V 10 O 28 )·17H 2 O, and its higher H 2 O content.

Description: Burroite, Ca 2 (NH 4 ) 2 (V 10 O 28 )·15H 2 O, is a new mineral species (IMA2016-079) discovered in the Burro mine, Slick Rock district, San Miguel County, Colorado, U.S.A. (38°2'42''N 108°53'23''W). The mineral is found as orange-yellow, somewhat flattened prisms up to 2 mm in length occurring on a montroseite- and corvusite-bearing sandstone. Burroite has yellow streak, vitreous luster, brittle tenacity, a Mohs hardness of 11/2–2, good cleavage on {001}, and irregular fracture. The measured density is 2.43(2) g·cm –3 . The partially determined optical properties are α = 1.764(3), β = n.d., 〉 1.81, orientation X a , Y probably c* . Electron probe microanalysis gave the empirical formula (based on 43 O apfu ) [Ca 1.88 (NH 4 ) 1.82 Na 0.18 ] 3.88 (H 0.23 V 5+ 10 O 28 )·15H 2 O. Burroite is triclinic, space group , with a 8.779(2), b 10.311(2), c 12.060(2) Å, α 96.740(4)°, β 107.388(5)°, and 114.439(6)°, and V = 911.2(3) Å 3 . The strongest four lines in the diffraction pattern are [ d in Å( I )( hkl )]: 11.06(100)(001), 9.02(46)(010), 8.10(21) , and 7.71(94) . The atomic arrangement of burroite was solved and refined to R 1 = 0.0946 for 2711 independent reflections with F 〉 4( F ). The structural unit in burroite is the [V 10 O 28 ] 6– decavanadate group; charge balance in the structure is maintained by the [Ca 2 (NH 4 ) 2 ·15H 2 O] 6+ interstitial complex. Linkage between the structural unit and the components of the interstitial complex is principally by hydrogen bonding. The mineral is named for the Burro mine in which it was found.

Description: Dagenaisite, Zn 3 Te 6+ O 6 , is a new mineral from the Gold Chain mine, Tintic district, Juab County, Utah, U.S.A. It is a late-stage secondary phase formed by the oxidative alteration of earlier Te- and Zn-bearing minerals. It is associated with cinnabar, dugganite, eurekadumpite, and gold in vugs in a matrix composed of quartz and dolomite. The mineral occurs as tiny light greenish-gray platelets, generally intermixed with amorphous material, forming porous masses that are apparently replacements of earlier phases. The streak is white, the luster is pearly, and crystals are transparent to translucent. The hardness could not be measured, but appears to be 〈2 (Mohs). The tenacity is flexible, the fracture is irregular, and cleavage was not observed. The calculated density is 6.00 g/cm 3 for the empirical formula. At room temperature, the mineral is slowly soluble in dilute HCl and rapidly soluble in concentrated HCl. Optical properties could not be determined. Electron-microprobe analyses gave the empirical formula (Zn 2.39 Cu 0.36 Ca 0.06 Mn 0.03 As 0.03 Si 0.02 ) 2.89 Te 1.02 O 6 . The mineral is monoclinic, space group C 2/ c , with cell parameters a 14.87(2), b 8.88(2), c 10.37(2) Å, β 93.33(2)°, V 1367(4) Å 3 , and Z = 12. The five strongest lines in the X-ray powder diffraction patterns are [ d obs Å( I )( hkl )]: 4.311(30)(310), 3.029(44)(222), 2.744(68) , 2.539(100) , and 1.6568(48) . The mineral is the natural counterpart of synthetic Zn 3 Te 6+ O 6 , which has a structure based on an approximate close packing of O atoms in an hhchhc sequence along [100].

Description: Kokinosite, Na 2 Ca 2 (V 10 O 28 )•24H 2 O, is a new mineral species from the St. Jude mine, Slick Rock district, San Miguel County, Colorado, USA. Kokinosite typically occurs as tablets or blades up to 0.05 mm thick, with stepped faces, and 1 mm in maximum dimension. Crystals are yellow orange, although sometimes they are tinted orange brown; the streak of the phase is yellow. The luster of kokinosite is subadamantine, and the mineral is transparent; it does not fluoresce in short- or long-wave radiation. The Mohs hardness is ca . 11/2. Kokinosite possesses a brittle tenacity, and displays one good cleavage on {01 $$\overline{1}$$ }. No parting was observed, and fracture is irregular. Density (calc.) = 2.353 g cm –3 on the basis of the empirical formula and the single-crystal cell data. Kokinosite is biaxial (–), with α 1.725(3), β 1.770(5), and 1.785(3). The 2 V was measured as 56.6(3)° from extinction data, and 2 V calc = 58.7°. Dispersion is r 〈 v, moderate. The optic orientation was incompletely determined, with X ^ a = 15°, Y b . The mineral is pleochroic: X, Z = orange yellow, Y = orange, and X = Z 〈 Y. Electron probe microanalysis and the crystal structure solution gave the empirical formula (based on V = 10 and O = 52 apfu ) (Na 1.88 K 0.01 ) 1.89 (Ca 1.81 Sr 0.12 ) 1.93 (V 10 O 28 )•24H 2 O. The simplified structural formula is Na 2 Ca 2 (V 10 O 28 )•24H 2 O. Kokinosite is triclinic, P $$\overline{1}$$ , with a 8.74899(19), b 10.9746(3), c 12.8216(9)Å, α 114.492(8), β 105.093(7), 91.111(6)°, V 1070.25(11) Å 3 , and Z = 1. The strongest four lines in the diffraction pattern are [ d in Å(I)( hkl )]: 9.88(100)(010,0 $$\overline{1}$$ 1), 7.92(36)( $$\overline{1}$$ 01), 8.42(33)(100), and 6.01(31)(1 $$\overline{1}$$ 1,110). The atomic arrangement of kokinosite was solved and refined to R 1 = 0.0379 for 3806 F o 〉 4 F reflections. The structural unit is a decavanadate polyanion, (V 10 O 28 ) 6– ; charge balance in the structure is maintained by the [Na 2 Ca 2 (H 2 O)24] 6+ interstitial unit that exists as Na(H 2 O) 6 octahedra and Ca(H 2 O) 8 polyhedra that link into chains by edge- and corner-sharing. The linkage between the structural unit and the interstitial unit occurs solely by hydrogen bonding. The new mineral is named in honor of Michael Kokinos (b. 1927) of Shingle Springs, California, a well-known mineral collector and member of the Micromounters’ Hall of Fame.

Description: Nashite, Na 3 Ca 2 [(V 4+ V 5+ 9 )O 28 ]•24H 2 O, is a new mineral species from the Little Eva mine, Yellow Cat District, Grand County, Utah, and the St. Jude mine, Slick Rock district, San Miguel County, Colorado, USA. Nashite occurs as blades on a corvusite-montroseite-bearing sandstone block intimately associated with calcite, gypsum, huemulite, pascoite, rossite, and sherwoodite. Nashite is bluish-green, with a light bluish-green streak. The mineral is transparent, with a subadamantine luster. Nashite does not fluoresce in short- or long-wave ultraviolet radiation, and has a hardness ca. 2. Nashite has a brittle tenacity, irregular fracture, and one good cleavage on {010}. Density (calc.) = 2.350 g/cm 3 based on the empirical formula and single-crystal cell data, and density (calc.) = 2.343 g/cm 3 based on the ideal formula and single-crystal cell data. Nashite is biaxial (–), with α 1.737(3), β 1.762(6), and 1.775(3). 2 V meas = 70(2)° and 2 V calc = 71°. Optic orientation is Y = b , X a . The mineral is pleochroic, with X greenish blue, Y yellowish green, and Z yellow, with X 〉 Y 〉〉 Z . Electron probe microanalysis and the crystal structure solution gave the empirical formula (based on O = 52): (Na 3.063 K 0.007 ) 3.070 (Ca 1.984 Sr 0.039 ) 2.019 [(V 4+ V 5+ 9 )O 28 ]•24(H 1.995 O). The simplified formula is Na 3 Ca 2 [(V 4+ V 5+ 9 )O 28 ] •24H 2 O. Nashite is monoclinic, P 2 1 / n , with a 10.0099(3), b 21.8472(7), c 11.1504(7) Å, and β 116.584(8)°. The strongest four lines in the diffraction pattern are [ d in Å( I )( hkl )]: 9.044(100)(111, 01), 8.350(64)(110), 10.995(46)(020), and 2.9942(29)(31, 32, 03, 071, 310). The atomic arrangement of nashite was solved and refined to R 1 = 0.0293. The structural unit in nashite is a partially-reduced decavanadate group, with a composition of [(V 4+ V 5+ 9 )O 28 ] 7– ; charge balance in the structure is maintained by the [Na 3 Ca 2 (OH 2 ) 22 •2H 2 O] 7+ interstitial unit. The interstitial unit consists of chains of Na1 and Na2 octahedra and an irregular CaO 2 (OH 2 ) 6 polyhedron. The chains are linked to the structural unit by direct bonding to oxygen atoms of the [(V 4+ V 5+ 9 )O 28 ] 7– group and extensive hydrogen bonding between the H 2 O molecules of the interstitial group and the oxygen atoms of the structural unit. The mineral is named for Dr. Barbara P. Nash (b. 1944), Professor of Geology and Geophysics at the University of Utah.