TY - JOUR
T1 - Pliniusite, Ca5(VO4)3F, a new apatite-group mineral and the novel natural ternary solid-solution system pliniusite-svabite-fluorapatite
AU - Pekov, Igor V.
AU - Koshlyakova, Natalia N.
AU - Zubkova, Natalia V.
AU - Krzãtała, Arkadiusz
AU - Belakovskiy, Dmitry I.
AU - Galuskina, Irina O.
AU - Galuskin, Evgeny V.
AU - Britvin, Sergey N.
AU - Sidorov, Evgeny G.
AU - Vapnik, Yevgeny
AU - Pushcharovsky, Dmitry Yu
N1 - Funding Information: We thank anonymous referees and Associate Editor Paolo Lotti for valuable comments. This work was supported by the Russian Science Foundation, grants nos. 19-17-00050 (mineralogical characterization and crystal structure study of pliniusite) and 20-77-00063 (chemical study of the pliniusite-svabite-fluorapatite solid-solution system). A.K. gives thanks for the support in the mineralogical study of Hatrurim pliniusite from the National Science Centre (NCN) of Poland, Grant Preludium no. 2016/21/N/ST10/00463. The technical support by the St. Petersburg State University X-ray Diffraction Resource Center in powder XRD study of pliniusite is acknowledged. Publisher Copyright: © 2022 Mineralogical Society of America.
PY - 2022/8/1
Y1 - 2022/8/1
N2 - The new apatite-group mineral pliniusite, ideally Ca5(VO4)3F, was found in fumarole deposits at the Tolbachik volcano, Kamchatka, Russia, and in a pyrometamorphic rock of the Hatrurim Complex, Israel. Pliniusite, together with fluorapatite and svabite, forms a novel and almost continuous ternary solid-solution system characterized by wide variations of T5+ = P, As, and V. In paleo-fumarolic deposits at Mountain 1004 (Tolbachik), members of this system, including the holotype pliniusite, are associated with hematite, tenorite, diopside, andradite, kainotropite, baryte and supergene volborthite, brochantite, gypsum and opal. In sublimates of the active Arsenatnaya fumarole (Tolbachik), pliniusite-svabite-fluorapatite minerals coexist with anhydrite, diopside, hematite, berzeliite, schäferite, calciojohillerite, forsterite, enstatite, magnesioferrite, ludwigite, rhabdoborite-group fluoroborates, powellite, baryte, udinaite, arsenudinaite, paraberzeliite, and spinel. At Nahal Morag, Negev Desert, Israel, the pliniusite cotype and V-bearing fluorapatite occur in schorlomite-gehlenite paralava with rankinite, walstromite, zadovite-aradite series minerals, magnesioferrite, hematite, khesinite, barioferrite, perovskite, gurimite, baryte, tenorite, delafossite, wollastonite, and cuspidine. Pliniusite forms hexagonal prismatic crystals up to 0.3 × 0.1 mm and open-work aggregates up to 2 mm across (Mountain 1004) or grains up to 0.02 mm (Nahal Morag and Arsenatnaya fumarole). Pliniusite is transparent to semitransparent, colorless or whitish, with a vitreous luster. The calculated density is 3.402 g/cm-3. Pliniusite is optically uniaxial (-), ω = 1.763(5), ϵ = 1.738(5). The empirical formulas of pliniusite type specimens calculated based on 13 anions (O+F+Cl) per formula unit are (Ca4.87Na0.06Sr0.03Fe0.02)ς4.98(V1.69As0.66P0.45S0.12Si0.09)ς3.01 O11.97F1.03 (Mountain 1004) and (Ca4.81Sr0.12Ba0.08Na0.05)ς5.06(V2.64P0.27S0.07Si0.03)ς3.01O12.15F0.51Cl0.34 (Nahal Morag). Pliniusite has a hexagonal structure with space group P63/m, a = b = 9.5777(7), c = 6.9659(5) Å, V = 553.39(7) Å3, and Z = 2. The structure was solved using single-crystal (holotype) X-ray difraction, R = 0.0254. The mineral was named in honor of the famous Roman naturalist Pliny the Elder, born Gaius Plinius Secundus (AD 23-79). It is suggested that the combination of high temperature, low pressure, and high oxygen fugacity favors the incorporation of V5+ into calcium apatite-type compounds, leading to the formation of fluorovanadates.
AB - The new apatite-group mineral pliniusite, ideally Ca5(VO4)3F, was found in fumarole deposits at the Tolbachik volcano, Kamchatka, Russia, and in a pyrometamorphic rock of the Hatrurim Complex, Israel. Pliniusite, together with fluorapatite and svabite, forms a novel and almost continuous ternary solid-solution system characterized by wide variations of T5+ = P, As, and V. In paleo-fumarolic deposits at Mountain 1004 (Tolbachik), members of this system, including the holotype pliniusite, are associated with hematite, tenorite, diopside, andradite, kainotropite, baryte and supergene volborthite, brochantite, gypsum and opal. In sublimates of the active Arsenatnaya fumarole (Tolbachik), pliniusite-svabite-fluorapatite minerals coexist with anhydrite, diopside, hematite, berzeliite, schäferite, calciojohillerite, forsterite, enstatite, magnesioferrite, ludwigite, rhabdoborite-group fluoroborates, powellite, baryte, udinaite, arsenudinaite, paraberzeliite, and spinel. At Nahal Morag, Negev Desert, Israel, the pliniusite cotype and V-bearing fluorapatite occur in schorlomite-gehlenite paralava with rankinite, walstromite, zadovite-aradite series minerals, magnesioferrite, hematite, khesinite, barioferrite, perovskite, gurimite, baryte, tenorite, delafossite, wollastonite, and cuspidine. Pliniusite forms hexagonal prismatic crystals up to 0.3 × 0.1 mm and open-work aggregates up to 2 mm across (Mountain 1004) or grains up to 0.02 mm (Nahal Morag and Arsenatnaya fumarole). Pliniusite is transparent to semitransparent, colorless or whitish, with a vitreous luster. The calculated density is 3.402 g/cm-3. Pliniusite is optically uniaxial (-), ω = 1.763(5), ϵ = 1.738(5). The empirical formulas of pliniusite type specimens calculated based on 13 anions (O+F+Cl) per formula unit are (Ca4.87Na0.06Sr0.03Fe0.02)ς4.98(V1.69As0.66P0.45S0.12Si0.09)ς3.01 O11.97F1.03 (Mountain 1004) and (Ca4.81Sr0.12Ba0.08Na0.05)ς5.06(V2.64P0.27S0.07Si0.03)ς3.01O12.15F0.51Cl0.34 (Nahal Morag). Pliniusite has a hexagonal structure with space group P63/m, a = b = 9.5777(7), c = 6.9659(5) Å, V = 553.39(7) Å3, and Z = 2. The structure was solved using single-crystal (holotype) X-ray difraction, R = 0.0254. The mineral was named in honor of the famous Roman naturalist Pliny the Elder, born Gaius Plinius Secundus (AD 23-79). It is suggested that the combination of high temperature, low pressure, and high oxygen fugacity favors the incorporation of V5+ into calcium apatite-type compounds, leading to the formation of fluorovanadates.
KW - apatite group
KW - calcium fluoride vanadate
KW - crystal structure
KW - electron microprobe analysis
KW - fluorapatite
KW - new mineral
KW - Pliniusite
KW - Raman spectroscopy
KW - svabite
KW - X-ray diffraction
UR - http://www.scopus.com/inward/record.url?scp=85130392830&partnerID=8YFLogxK
U2 - https://doi.org/10.2138/am-2022-8100
DO - https://doi.org/10.2138/am-2022-8100
M3 - Article
SN - 0003-004X
VL - 107
SP - 1626
EP - 1634
JO - American Mineralogist
JF - American Mineralogist
IS - 8
ER -