TY - JOUR

T1 - Fluorpyromorphite, Pb5 (PO4)3 F, a new apatite-group mineral from Sukhovyaz Mountain, Southern Urals, and Tolbachik volcano, Kamchatka

AU - Kasatkin, Anatoly V.

AU - Pekov, Igor V.

AU - Škoda, Radek

AU - Chukanov, Nikita V.

AU - Nestola, Fabrizio

AU - Agakhanov, Atali A.

AU - Kuznetsov, Aleksey M.

AU - Koshlyakova, Natalia N.

AU - Plášil, Jakub

AU - Britvin, Sergey N.

PY - 2023/2/20

Y1 - 2023/2/20

N2 - Fluorpyromorphite, ideally Pb5 (PO4)3 F, a new apatite-group member, an F-dominant analog of pyromorphite and hydrox-ylpyromorphite. It is a supergene mineral found at two localities: Sukhovyaz Mountain, Ufaley District, Southern Urals (holotype) and Mountain 1004, Tolbachik volcano, Kamchatka (co-type), both in Russia. At Sukhovyaz, fluorpyromorphite forms anhedral grains up to 0.2 mm across (usually much smaller), filling cavities in quartz and sometimes partially replacing fluorapatite. Associated supergene minerals include pyromorphite, hydroxylpyromorphite, fluorphosphohedy-phane, mimetite, and nickeltsumcorite. At Tolbachik, fluorpyromorphite occurs in the oxidation zone of paleo-fumarolic deposits in close association with pyromorphite, fluorphosphohedyphane, wulfenite, cerussite, munakataite, vanadinite, chrysocolla, and opal. It forms crude long-prismatic to acicular crystals up to 0.1 mm long and up to 5 μm thick combined in bunches and spherulites up to 0.2 mm. Fluorpyromorphite is colorless (Sukhovyaz) or yellow (Tolbachik), translucent to transparent and has a vitreous luster. It is brittle, with an uneven fracture and poor cleavage on (001). The calculated density values are 7.382 (holotype) and 6.831 (cotype) g/cm3. Fluorpyromorphite is optically uniaxial (–). In reflected light, it is light-grey, weakly anisotropic. The reflectance values (Rmin /Rmax, %) are: 15.8/16.6 (470 nm), 16.2/17.2 (546 nm), 15.9/16.9 (589 nm), 15.4/16.2 (650 nm). The chemical composition is (electron microprobe, wt. %; holotype/co-type): CaO 0.10/3.16, SrO 0.17/0.00, PbO 83.51/77.39, P2 O5 16.13/16.35, CrO3 0.00/0.49, SeO3 0.00/0.98, F 1.00/1.35, Cl 0.29/0.40, H2 Ocalc 0.13/0.00, –O=(F,Cl) –0.49/–0.66, total 100.84/99.46. The empirical formulae based on 13 anions (O + F + Cl + OH) pfu are Pb4.95 Ca0.02 Sr0.02 P3.00 O12 F0.70 (OH)0.19 Cl0.11 (holotype) and Pb4.26 Ca0.69 P2.83 Se6+0.09Cr6+0.06 O11.99 F0.87 Cl0.14 (co-type). Fluorpyromorphite is hexagonal, space group P63 /m, unit-cell parameters (from powder X-ray diffraction data; holotype / co-type) are: a = 9.779(5) / 9.732(1), c = 7.241(9) / 7.242(1) Å, V = 599.6(7) / 594.0(2) Å3, and Z = 2. The crystal structure was refined using the Rietveld method to Rp = 0.1764 (holotype). Fluorpyromorphite is isostructural with other members of the apatite group, a subdivision of the apatite supergroup.

AB - Fluorpyromorphite, ideally Pb5 (PO4)3 F, a new apatite-group member, an F-dominant analog of pyromorphite and hydrox-ylpyromorphite. It is a supergene mineral found at two localities: Sukhovyaz Mountain, Ufaley District, Southern Urals (holotype) and Mountain 1004, Tolbachik volcano, Kamchatka (co-type), both in Russia. At Sukhovyaz, fluorpyromorphite forms anhedral grains up to 0.2 mm across (usually much smaller), filling cavities in quartz and sometimes partially replacing fluorapatite. Associated supergene minerals include pyromorphite, hydroxylpyromorphite, fluorphosphohedy-phane, mimetite, and nickeltsumcorite. At Tolbachik, fluorpyromorphite occurs in the oxidation zone of paleo-fumarolic deposits in close association with pyromorphite, fluorphosphohedyphane, wulfenite, cerussite, munakataite, vanadinite, chrysocolla, and opal. It forms crude long-prismatic to acicular crystals up to 0.1 mm long and up to 5 μm thick combined in bunches and spherulites up to 0.2 mm. Fluorpyromorphite is colorless (Sukhovyaz) or yellow (Tolbachik), translucent to transparent and has a vitreous luster. It is brittle, with an uneven fracture and poor cleavage on (001). The calculated density values are 7.382 (holotype) and 6.831 (cotype) g/cm3. Fluorpyromorphite is optically uniaxial (–). In reflected light, it is light-grey, weakly anisotropic. The reflectance values (Rmin /Rmax, %) are: 15.8/16.6 (470 nm), 16.2/17.2 (546 nm), 15.9/16.9 (589 nm), 15.4/16.2 (650 nm). The chemical composition is (electron microprobe, wt. %; holotype/co-type): CaO 0.10/3.16, SrO 0.17/0.00, PbO 83.51/77.39, P2 O5 16.13/16.35, CrO3 0.00/0.49, SeO3 0.00/0.98, F 1.00/1.35, Cl 0.29/0.40, H2 Ocalc 0.13/0.00, –O=(F,Cl) –0.49/–0.66, total 100.84/99.46. The empirical formulae based on 13 anions (O + F + Cl + OH) pfu are Pb4.95 Ca0.02 Sr0.02 P3.00 O12 F0.70 (OH)0.19 Cl0.11 (holotype) and Pb4.26 Ca0.69 P2.83 Se6+0.09Cr6+0.06 O11.99 F0.87 Cl0.14 (co-type). Fluorpyromorphite is hexagonal, space group P63 /m, unit-cell parameters (from powder X-ray diffraction data; holotype / co-type) are: a = 9.779(5) / 9.732(1), c = 7.241(9) / 7.242(1) Å, V = 599.6(7) / 594.0(2) Å3, and Z = 2. The crystal structure was refined using the Rietveld method to Rp = 0.1764 (holotype). Fluorpyromorphite is isostructural with other members of the apatite group, a subdivision of the apatite supergroup.

KW - Southern Urals

KW - Sukhovyaz Mountain

KW - Tolbachik volcano

KW - apatite group

KW - fluorpyromorphite

KW - new mineral

UR - https://www.mendeley.com/catalogue/936844fb-5d8c-35dd-9352-965dad2741cb/

U2 - 10.3190/jgeosci.368

DO - 10.3190/jgeosci.368

M3 - Article

VL - 68

SP - 81

EP - 93

JO - Journal of Geosciences

JF - Journal of Geosciences

SN - 1802-6222

IS - 1

ER -