ALBERT

Description: A bstract Apatite is the most abundant phosphate mineral on Earth and forms the foundation of the global phosphorus cycle. Interest in apatite crosses many disciplines, including geology, agriculture, material science, dentistry, and medicine, and the phase is also used extensively in many manufacturing processes. Apatite is the main source of phosphate for fertilizer, and adequate sources of apatite are essential for production of fertilizers that are necessary for feeding the world’s population. Despite the importance of the phase, the atomic arrangement of apatite is not well understood. The natural apatite anion solid solution among F, OH, and Cl (fluorapatite, hydroxylapatite, and chlorapatite, respectively) is one of those rare solid solutions wherein the atomic arrangements of the binary and ternary solid solutions are not predictable from the atomic arrangements of the endmembers of the ternary system; the steric interactions in the (F, OH, Cl) apatite anion column are complex as the three anions mix. Although the first detailed account of the atomic arrangement of binary apatites along the F-Cl join was recently reported using painstakingly synthesized samples, natural Cl-rich fluorapatite, although long-sought, had not been identified; an Earth environment that has high fugacity of F and Cl, but is devoid of OH, is rare. Here we report the atomic arrangement of a natural Cl-rich fluorapatite from the Three Peaks area of Utah (USA) that is essentially devoid of OH. The structure ( R 1 = 0.0145) of the P 6 3 / m apatite is similar to that obtained from synthetic samples, and demonstrates that solid solution along the F–Cl join in natural apatites is achieved by creation of a second F site (F b ) in the Cl-rich fluorapatite [0, 0, z ] anion column, an off-mirror site at z = 0.178, coupled with the presence of a site for Cl (Cl b ), that differs from the Cl site in endmember chlorapatite. The combination of a Cl site that relaxes toward its associated mirror plane and a neighboring F site that relaxes away from its associated mirror plane allows sufficient separation of F and Cl in the anion column for the two anions to coexist. The structure described herein is the first reported structure of a natural Cl-rich fluorapatite.

Description: 〈span〉〈div〉Abstract〈/div〉Pandoraite-Ba, BaV〈sup〉4+〈/sup〉〈sub〉5〈/sub〉V〈sup〉5+〈/sup〉〈sub〉2〈/sub〉O〈sub〉16〈/sub〉·3H〈sub〉2〈/sub〉O, and pandoraite-Ca, CaV〈sup〉4+〈/sup〉〈sub〉5〈/sub〉V〈sup〉5+〈/sup〉〈sub〉2〈/sub〉O〈sub〉16〈/sub〉·3H〈sub〉2〈/sub〉O, are two new vanadium-oxide-bronze minerals from the Pandora mine, La Sal district, San Juan County, Colorado, USA. Pandoraite-Ba and pandoraite-Ca are rare secondary minerals and occur on a matrix consisting of recrystallized quartz grains from the original sandstone. Crystals of carnotite are associated with pandoraite-Ba and crystals of finchite are associated with pandoraite-Ca. The minerals occur as thin, dark blue, square plates up to approximately 100 μm across and approximately 2 μm thick. Plates occur in subparallel to random intergrowths. The streak of both minerals is light greenish blue, and they display a vitreous, transparent luster and brittle tenacity; neither mineral displays fluorescence. The Mohs hardness of pandoraite-Ba and pandoraite-Ca is 〈span〉ca〈/span〉. 2½. Cleavage for both minerals is perfect on {001}. For pandoraite-Ba, density〈sub〉meas〈/sub〉 = 3.24(1) g/cm〈sup〉3〈/sup〉. For pandoraite-Ca, density〈sub〉meas〈/sub〉 = 2.91(1) g/cm〈sup〉3〈/sup〉. Both minerals are biaxial (pseudo-uniaxial) (–). For pandoraite-Ba, α (ε) =1.81(2), β and γ (ω) = 1.84(1). For pandoraite-Ca, α (ε) = 1.80(2), β and γ (ω) = 1.83(1). Similar greenish-blue pleochroism is found in both minerals, 〈span〉Y〈/span〉 and 〈span〉Z〈/span〉 (〈span〉O〈/span〉) 〉 〈span〉X〈/span〉 (〈span〉E〈/span〉). For pandoraite-Ba, the empirical formula from electron probe microanalysis (EPMA) (calculated on the basis of V + Fe + Al = 7 and O = 19 〈span〉apfu〈/span〉) is (Ba〈sub〉0.83〈/sub〉Sr〈sub〉0.09〈/sub〉Ca〈sub〉0.05〈/sub〉Na〈sub〉0.03〈/sub〉K〈sub〉0.02〈/sub〉)〈sub〉Σ1.02〈/sub〉(V〈sup〉4+〈/sup〉〈sub〉4.25〈/sub〉V〈sup〉5+〈/sup〉〈sub〉2.38〈/sub〉Fe〈sup〉3+〈/sup〉〈sub〉0.35〈/sub〉Al〈sub〉0.02〈/sub〉)〈sub〉Σ7.00〈/sub〉O〈sub〉16〈/sub〉·3H〈sub〉2〈/sub〉O, and for pandoraite-Ca it is (Ca〈sub〉0.62〈/sub〉Ba〈sub〉0.07〈/sub〉Sr〈sub〉0.02〈/sub〉Na〈sub〉0.01〈/sub〉K〈sub〉0.01〈/sub〉)〈sub〉Σ0.73〈/sub〉(V〈sup〉4+〈/sup〉〈sub〉3.70〈/sub〉V〈sup〉5+〈/sup〉〈sub〉2.93〈/sub〉Fe〈sup〉3+〈/sup〉〈sub〉0.37〈/sub〉Al〈sub〉0.01〈/sub〉)〈sub〉Σ7.01〈/sub〉O〈sub〉16〈/sub〉·3H〈sub〉2〈/sub〉O. EPMA demonstrates that solid solution exists between the phases. Pandoraite-Ba is monoclinic (pseudo-tetragonal), 〈span〉P〈/span〉2, with 〈span〉a〈/span〉 6.1537(16), 〈span〉b〈/span〉 6.1534(18), 〈span〉c〈/span〉 21.356(7) Å, β 90.058(9)°, and 〈span〉V〈/span〉 808.7(4) Å〈sup〉3〈/sup〉, determined by single-crystal X-ray diffractometry. Pandoraite-Ca, inferred to be isostructural with the Ba-dominant phase, has 〈span〉a〈/span〉 6.119(8), 〈span〉b〈/span〉 6.105(8), 〈span〉c〈/span〉 21.460(9)Å, β 90.06(14)°, and 〈span〉V〈/span〉 801.7(15) Å〈sup〉3〈/sup〉, determined by refinement of powder diffraction data. The atomic arrangement of pandoraite-Ba was solved and refined to 〈span〉R〈/span〉〈sub〉1〈/sub〉 = 0.0573 for 3652 independent reflections with 〈span〉I〈/span〉 〉 2σ〈span〉I〈/span〉. Pandoraite-Ba and pandoraite-Ca have vanadium oxide bronze layer structures formed of sheets of V〈sub〉7〈/sub〉O〈sub〉16〈/sub〉 polyhedra that form the structural unit and (Ba,Ca)(H〈sub〉2〈/sub〉O)〈sub〉3〈/sub〉 interlayers; the vanadium is of mixed valence (4〈sup〉+〈/sup〉, 5〈sup〉+〈/sup〉), with the reduction of pentavalent vanadium occurring to balance the charge of the Ba “insertion” ions in partially occupied sites in the interlayer. A tetragonal synthetic analog is known.〈/span〉

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: The iron oxide-apatite (IOA) deposits of the eastern Adirondack Mountains consist of intrusive sheets or dikes of magnetite, fluorapatite, augitic pyroxene, quartz, and microcline. Other trace mineral phases include ilmenite with hematite exsolution, V-rich titanite rimming magnetite, zircon, monazite-(Ce), stillwellite-(Ce), lanthanite-(Ce), allanite-(Ce), and thorite. Observations under transmitted light show polygonal and cumulate textures. The ore bodies, each with knife-edge contacts with the host gneisses, are closely associated in time with A-type leucogranites and granitic gneisses ( ca . 1070–1050 Ma). Backscattered electron (BSE) images highlight the following types of fluorapatite-monazite-(Ce) relations that formed as a result of metamorphism and fluid-rock interaction: (1) areas of relatively low BSE intensities containing tiny secondary monazite-(Ce) and thorite crystals developed within brighter apatite grains and along crystal margins and fractures; (2) areas of low BSE intensity within larger fluorapatite grains; (3) oriented rods of quartz in fluorapatite; (4) monazite-(Ce) rimming fluorapatite; and (5) multi-domain clusters of fluorapatite in unzoned fluorapatite. Fluorapatite samples from these IOA deposits were analyzed by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) for major and trace elements. All grains contain high concentrations of light and heavy rare earth elements and yttrium, and samples from some deposits are exceptionally enriched in heavy rare earth elements and yttrium. The crystal structures of the fluorapatites from Cheever, Mineville, Palmer Hill, Arnold Hill, and Rutgers mine were analyzed. Rare earth elements (REE) are dominant at the Ca2 site, and in the most REE-rich sample, from Cheever, 5.7% of the Ca2 sites and 3.5% of the Ca1 sites are occupied by REEs. We consider that the most likely geological scenario for the incorporation of the REEs in fluorapatite includes high concentrations of incompatible elements in a dense iron- and phosphorus-rich melt that formed by immiscibility with the silicate melt of the Lyon Mountain granite. The high REE concentration appears to have been accommodated in the fluorapatite structure through a coupled substitution with Si 4+ . A later, low-temperature stage of fluid infiltration, probably at greenschist facies conditions, re-mobilized the REE and produced secondary minerals within the ore, including low-actinide bearing monazite-(Ce), tremolite, ferro-actinolite, chlorite, rutile, and hematite.

Description: A bstract Bluestreakite, K 4 Mg 2 (V 4+ 2 V 5+ 8 O 28 )·14H 2 O, is a new mineral species from the Blue Streak mine, Bull Canyon, Montrose County, Colorado, USA. Bluestreakite typically occurs as irregular polycrystalline coatings on rounded quartz grains or masses of montroseite, and rarely as tablets or blades. It grows on corvusite-montroseite-bearing sandstone blocks intimately associated with gypsum, huemulite, hummerite, metamunirite, and munirite. Bluestreakite is dark greenish blue, with a light blue streak. The mineral is transparent, with a subadamantine luster. Bluestreakite does not fluoresce in short- or long-wave ultraviolet radiation, and it has a hardness ca . 2. Bluestreakite has a brittle tenacity, irregular fracture, and no cleavage. Density (calc.) = 2.630 g⋅cm –3 based on the empirical formula and single-crystal cell data. Bluestreakite is biaxial (–), with α 1.750(5), β 1.800(5), 1.829 (calc.) (white light); 2 V meas. = 73(3)°. Optic orientation is Z = b ( X and Y not determined). The pleochroism is slight, with X 〈 Y Z dark greenish blue. Electron probe microanalysis gave the empirical formula (based on O = 42) (K 3.37 Na 0.15 ) 3.52 Mg 1.94 (V 4+ 1.40 V 5+ 8.60 )O 28 ·14H 2 O. Bluestreakite is monoclinic, P 2 1 / n , with a 12.2383(7), b 10.3834(4), c 14.1945(6) Å, β 103.008(2)°, V 1757.48(14) Å 3 , and Z = 2. The strongest four lines in the diffraction pattern are [ d in Å( I )( hkl )]: 10.34(57)( 1{macron} 01), 8.27(100)(011,101), 7.90(21)(110), and 1.9814(22)( 1{macron} 17, 2{macron} 17). The atomic arrangement of bluestreakite was solved and refined to R 1 = 0.0339 for 7395 independent reflections with F 〉 4 ( F ). The structural unit in bluestreakite is a partially reduced decavanadate group, with an ideal composition of [(V 4+ 2 V 5+ 8 )O 28 ] 8– ; charge balance in the structure is maintained by the [K 4 Mg 2 ⋅14H 2 O] 8+ interstitial complex. The interstitial complex is formed of irregular K1[O 4 (H 2 O) 4 ] and K2[O 6 (H 2 O) 3 ] polyhedra, and a Mg(H 2 O) 6 octahedron. Bonding between the interstitial complex and the structural unit takes place through direct bonding of the K1 and K2 atoms of the interstitial complex with the oxygen atoms of the structural unit, as well as extensive hydrogen bonding.

Description: 〈span〉〈div〉Abstract〈/div〉The crystal structure of a green, transparent, vanadium-rich muscovite-2〈span〉M〈/span〉〈sub〉1〈/sub〉 (V〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 = 11.35 wt.%, one of the highest amounts reported to date in muscovite) with the optimized formula (K〈sub〉0.94〈/sub〉Na〈sub〉0.06〈/sub〉)〈span〉M〈/span〉〈sub〉2〈/sub〉(Al〈sub〉1.20〈/sub〉V〈sup〉3+〈/sup〉〈sub〉0.61〈/sub〉Mg〈sub〉0.12〈/sub〉Cr〈sup〉3+〈/sup〉〈sub〉0.07〈/sub〉)〈span〉T〈/span〉〈sub〉1〈/sub〉(Si〈sub〉1.54〈/sub〉Al〈sub〉0.46〈/sub〉)〈span〉T〈/span〉〈sub〉2〈/sub〉(Si〈sub〉1.54〈/sub〉Al〈sub〉0.46〈/sub〉)O〈sub〉10〈/sub〉(OH)〈sub〉2〈/sub〉 and space group C2/〈span〉c〈/span〉, 〈span〉a〈/span〉 5.2255(6), 〈span〉b〈/span〉 9.0704(10), 〈span〉c〈/span〉 20.0321(21) Å, β 95.773(2)°, 〈span〉Z〈/span〉 = 4 has been refined to 〈span〉R〈/span〉 = 6.97% for 1070 unique reflections (Mo〈span〉K〈/span〉α). This muscovite, which occurs in small quartz veins in graphite schist from Weinberg mountain, near the village of Amstall, Lower Austria, is distinctly low in Cr (Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 ∼1.4 wt.%) and Mg (MgO ∼1.1 wt.%); Fe, Mn, and Ti are below detection limit. All octahedral cations occupy the 〈span〉M〈/span〉2 site, and the average octahedral bond (〈span〉M〈/span〉2–O) distance is 1.953 Å. Structural distortions include α = 8.89° and Δ〈span〉z〈/span〉 = 0.193 Å, resulting in an interlayer spacing of 3.35 Å. The optical absorption spectrum of this V-rich muscovite shows absorption features at 427 and 609 nm that define a transmission window centered at 523 nm. These absorption features are consistent with those expected for V〈sup〉3+〈/sup〉 in mica, but the 609 nm band has a slightly longer wavelength than in low-V micas.〈/span〉

Description: 〈span〉〈div〉Abstract〈/div〉The crystal structure of a green, transparent, vanadium-rich muscovite-2〈span〉M〈/span〉〈sub〉1〈/sub〉 (V〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 = 11.35 wt.%, one of the highest amounts reported to date in muscovite) with the optimized formula (K〈sub〉0.94〈/sub〉Na〈sub〉0.06〈/sub〉)〈span〉M〈/span〉〈sub〉2〈/sub〉(Al〈sub〉1.20〈/sub〉V〈sup〉3+〈/sup〉〈sub〉0.61〈/sub〉Mg〈sub〉0.12〈/sub〉Cr〈sup〉3+〈/sup〉〈sub〉0.07〈/sub〉)〈span〉T〈/span〉〈sub〉1〈/sub〉(Si〈sub〉1.54〈/sub〉Al〈sub〉0.46〈/sub〉)〈span〉T〈/span〉〈sub〉2〈/sub〉(Si〈sub〉1.54〈/sub〉Al〈sub〉0.46〈/sub〉)O〈sub〉10〈/sub〉(OH)〈sub〉2〈/sub〉 and space group C2/〈span〉c〈/span〉, 〈span〉a〈/span〉 5.2255(6), 〈span〉b〈/span〉 9.0704(10), 〈span〉c〈/span〉 20.0321(21) Å, β 95.773(2)°, 〈span〉Z〈/span〉 = 4 has been refined to 〈span〉R〈/span〉 = 6.97% for 1070 unique reflections (Mo〈span〉K〈/span〉α). This muscovite, which occurs in small quartz veins in graphite schist from Weinberg mountain, near the village of Amstall, Lower Austria, is distinctly low in Cr (Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 ∼1.4 wt.%) and Mg (MgO ∼1.1 wt.%); Fe, Mn, and Ti are below detection limit. All octahedral cations occupy the 〈span〉M〈/span〉2 site, and the average octahedral bond (〈span〉M〈/span〉2–O) distance is 1.953 Å. Structural distortions include α = 8.89° and Δ〈span〉z〈/span〉 = 0.193 Å, resulting in an interlayer spacing of 3.35 Å. The optical absorption spectrum of this V-rich muscovite shows absorption features at 427 and 609 nm that define a transmission window centered at 523 nm. These absorption features are consistent with those expected for V〈sup〉3+〈/sup〉 in mica, but the 609 nm band has a slightly longer wavelength than in low-V micas.〈/span〉

Description: Food contains inorganic elements and compounds that are important for human nutrition and human health. Although these substances have been investigated and characterized in many foods for their nutritive value, little is known about the crystal phases that form in foods. In this study, we investigated crystals that form in the bacterial smears on the surface of washed-rind cheese. Washed-rind cheeses have been consumed for centuries, but the crystals that often contribute detectable grittiness to the surface of these cheeses have never been identified. The crystals were characterized with petrographic microscopy and identified with single crystal X-ray diffractometry as ikaite (CaCO 3 ·6H 2 O), a rare metastable phase that has only been observed in freezing marine and lacustrine environments, and struvite (NH 4 MgPO 4 ·6H 2 O), a mineral that is often associated with bacterial activity. These crystals are important to cheesemakers because they affect cheese texture and sensory characteristics. The potential importance of the bacterial smear in the nucleation of these phases is discussed, and the possibility of using cheese as a model system to investigate geological biomineralization phenomena is explored.

Description: Wernerbaurite (IMA 2012–064) and schindlerite (IMA 2012–063) from the St. Jude mine, Slick Rock district, San Miguel County, Colorado, USA, were described as hydronium-bearing decavanadate minerals with the formulae {[Ca(H 2 O) 7 ] 2 (H 2 O) 2 (H 3 O) 2 }{V 10 O 28 } and {[Na 2 (H 2 O) 10 ](H 3 O) 4 }{V 10 O 28 }, respectively. Because these phases correspond to known synthetic phases with these formulae, the presence of NH 4 in these minerals was not considered. Recent investigations of a similar phase discovered at a vanadium locality in the Fergana Valley of Kyrgyzstan showed it to contain NH 4 , leading us to reanalyze the original electron-microprobe mounts of wernerbaurite and schindlerite, specifically seeking N; those analyses confirmed the presence of sufficient NH 4 to replace the originally assigned H 3 O. With the additional H sites included and O replaced by N at the NH 4 sites, the structure refinement residual improved for wernerbaurite from R 1 = 3.41% to R 1 = 3.26% and for schindlerite from R 1 = 3.99% to R 1 = 3.70%. The newly assigned NH 4 sites exhibited normal NH 4 –O bond distances and coordination and reasonable bond-valence sums. The H 3 O synthetic equivalents of both phases had been reported, as well as the NH 4 synthetic equivalent of schindlerite. Subsequent to the publication of the original description of the minerals, the NH 4 equivalent of wernerbaurite has also been reported.