TY - JOUR

T1 - Napoliite, Pb2OFCl, a new mineral from Vesuvius volcano, and its relationship with dimorphous rumseyite

AU - Касаткин, Анатолий

AU - Сийдра, Олег Иоханнесович

AU - Nestola, Fabrizio

AU - Pekov, I.V.

AU - Агаханов, Атали

AU - Koshlyakova, Natalya N.

AU - Chukanov, N. V.

AU - Назарчук, Евгений Васильевич

AU - Molinari, Simone

AU - Rossi, Manuela

PY - 2023/10/14

Y1 - 2023/10/14

N2 - Napoliite, ideally Pb 2 OFCl, is a new fluoroxychloride mineral found in a specimen from a fumarole formed subsequent to the 1944 eruption of Vesuvius volcano, Naples Province, Italy. It occurs as well-shaped lamellar crystals up to 0.25 × 0.25 × 0.01 mm typically forming clusters up to 0.4 × 0.4 mm on the surface of volcanic scoria in association with anglesite, artroeite, atacamite, calcioaravaipaite, cerussite, challacolloite, cotunnite, hephaistosite, manuelarossiite, matlockite and susannite. Napoliite is colourless with white streak and adamantine lustre. It is brittle and has a laminated fracture. Cleavage is perfect on {001}. D calc = 7.797 g cm –3 . The calculated mean refractive index is 2.10. Chemical composition (wt.%, electron microprobe) is: PbO 91.71, F 3.89, Cl 7.34, –O=(F+Cl) –3.30, total 99.64. The empirical formula calculated on the basis of 3 anions is Pb 1.999 O 0.997 F 0.996 Cl 1.007 . Raman spectroscopy confirms the absence of OH – groups and H 2 O molecules in the mineral. Napoliite is tetragonal, space group P 4 2 / mcm , a = 5.7418(11), c = 12.524(4) Å, V = 412.9(2) Å 3 and Z = 4. The strongest lines of the powder X-ray diffraction pattern [ d , Å ( I , %) ( hkl )] are: 3.860 (85) (111); 3.139 (20) (004); 2.914 (100) (113); 2.866 (63) (200); 2.118 (19) (204); 2.027 (19) (220); 1.665 (20) (313); and 1.642 (23) (117). The crystal structure was refined to R 1 = 0.024 for 222 reflections with F > 4σ( F ). It is based on lead oxide blocks derived from that of litharge PbO, which alternate with layers of chloride ions. Napoliite represents a new structure type with a unique order/disorder pattern of fluorine and oxygen atoms. The new mineral is dimorphous with rumseyite. It is named after the city of Naples (Napoli in Italian).

AB - Napoliite, ideally Pb 2 OFCl, is a new fluoroxychloride mineral found in a specimen from a fumarole formed subsequent to the 1944 eruption of Vesuvius volcano, Naples Province, Italy. It occurs as well-shaped lamellar crystals up to 0.25 × 0.25 × 0.01 mm typically forming clusters up to 0.4 × 0.4 mm on the surface of volcanic scoria in association with anglesite, artroeite, atacamite, calcioaravaipaite, cerussite, challacolloite, cotunnite, hephaistosite, manuelarossiite, matlockite and susannite. Napoliite is colourless with white streak and adamantine lustre. It is brittle and has a laminated fracture. Cleavage is perfect on {001}. D calc = 7.797 g cm –3 . The calculated mean refractive index is 2.10. Chemical composition (wt.%, electron microprobe) is: PbO 91.71, F 3.89, Cl 7.34, –O=(F+Cl) –3.30, total 99.64. The empirical formula calculated on the basis of 3 anions is Pb 1.999 O 0.997 F 0.996 Cl 1.007 . Raman spectroscopy confirms the absence of OH – groups and H 2 O molecules in the mineral. Napoliite is tetragonal, space group P 4 2 / mcm , a = 5.7418(11), c = 12.524(4) Å, V = 412.9(2) Å 3 and Z = 4. The strongest lines of the powder X-ray diffraction pattern [ d , Å ( I , %) ( hkl )] are: 3.860 (85) (111); 3.139 (20) (004); 2.914 (100) (113); 2.866 (63) (200); 2.118 (19) (204); 2.027 (19) (220); 1.665 (20) (313); and 1.642 (23) (117). The crystal structure was refined to R 1 = 0.024 for 222 reflections with F > 4σ( F ). It is based on lead oxide blocks derived from that of litharge PbO, which alternate with layers of chloride ions. Napoliite represents a new structure type with a unique order/disorder pattern of fluorine and oxygen atoms. The new mineral is dimorphous with rumseyite. It is named after the city of Naples (Napoli in Italian).

UR - https://www.mendeley.com/catalogue/526666f1-6096-3914-b15e-be072c71aadd/

U2 - 10.1180/mgm.2023.43

DO - 10.1180/mgm.2023.43

M3 - Article

VL - 87

SP - 711

EP - 718

JO - Mineralogical Magazine

JF - Mineralogical Magazine

SN - 0026-461X

IS - 5

ER -