Pliniusite, Ca5(VO4)3F, a new apatite-group mineral and the novel natural ternary solid-solution system pliniusite-svabite-fluorapatite

Igor V. Pekov, Natalia N. Koshlyakova, Natalia V. Zubkova, Arkadiusz Krzãtała, Dmitry I. Belakovskiy, Irina O. Galuskina, Evgeny V. Galuskin, Sergey N. Britvin, Evgeny G. Sidorov, Yevgeny Vapnik, Dmitry Yu Pushcharovsky

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)1626-1634
Number of pages9
JournalAmerican Mineralogist
Volume107
Issue number8
DOIs
StatePublished - 1 Aug 2022

Keywords

  • apatite group
  • calcium fluoride vanadate
  • crystal structure
  • electron microprobe analysis
  • fluorapatite
  • new mineral
  • Pliniusite
  • Raman spectroscopy
  • svabite
  • X-ray diffraction

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

Fingerprint

Dive into the research topics of 'Pliniusite, Ca5(VO4)3F, a new apatite-group mineral and the novel natural ternary solid-solution system pliniusite-svabite-fluorapatite'. Together they form a unique fingerprint.

Cite this