Biachellaite (Na,Ca,K)8(Si6Al6O24)(SO4)2(OH)0.5×H2O, a new mineral of the cancrinite group
- Autor(en)
- Gerald Giester, N V Chukanov, Igor V Pekov, Dmitry Y. Pushcharovsky, Natalia V Zubkova, Aleksandr E. Zadov
- Abstrakt
A new mineral biachellaite was found in a volcanic ejectum in the Biachella Valley, Sacrofano Caldera, Sacrofano municipality, Rome province, Latium region, Italy, in assocn. with rock-forming sanidine, diopside, andradite, leucite and hauyne. The name is given for discovery locality. Biachellaite forms equant dipyramidal-pinacoidal crystals up to 1 cm in cavitites. Transparent, colorless, streak is white, lustre is vitreous. Brittle, Mohs' hardness 5. Perfect cleavage is obsd. on {10.hivin.10}, imperfect cleavage (parting) - on {0001}. Dmeas = 2.51(1) g/cm3 (by equilibration in heavy liqs.). Calcd. d. is 2.515 g/cm3 (with single-crystal X-ray data) and 2.520 g/cm3 (with powder data). Uniaxial, pos., ? = 1.512(1), .vepsiln. = 1.514(1). IR spectrum is given. Chem. compn. (electron microprobe, water - by TG data): Na2O 10.06, K2O 5.85, CaO 12.13, Al2O3 26.17, SiO2 31.46, SO3 12.71, Cl 0.45, H2O 1.6, -O=Cl2 -0.10, total 100.33. The empirical formula (Z = 15) is: (Na3.76Ca2.50K1.44)S7.70(Si6.06Al5.94O24)(SO4)1.84Cl0.15(OH)0.43x0.81H2O. The simplified formula is: (Na,Ca,K)8(Si6Al6O24)(SO4)2(OH)0.5xH2O. Biachellaite is trigonal, space group P3, a = 12.913(1), c = 79.605(5); V = 11495(1)3. The crystal structure of biachellaite is characterized by the 30-layer stacking sequence (ABCABCACACBACBACBCACBACBACBABC).infin.. The tetrahedral Al,Si,O framework contains cavities of four types: cancrinite, sodalite, losod and liottite ones. The strongest lines of the X-ray powder diffraction pattern [d, (I, %) (hkl)] are: 11.07 (19) (100, 101), 6.45 (18) (110, 111), 3.720 (100) (2.1.10, 300, 301, 2.0.16, 302), 3.576 (18) (1.0.21, 2.0.17, 306), 3.300 (47) (1.0.23, 2.1.15), 3.220 (16) (2.1.16, 222). The holotype specimen is deposited in Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, with registration no. 3642/1.
- Organisation(en)
- Institut für Mineralogie und Kristallographie
- Externe Organisation(en)
- Russian Academy of Sciences, Lomonosov Moscow State University (MSU), NPO Regenerator
- Journal
- Proceedings of the Russian Mineralogical Society
- Band
- 137
- Seiten
- 57-66
- Anzahl der Seiten
- 10
- ISSN
- 0869-6055
- Publikationsdatum
- 2008
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105113 Kristallographie
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/a2cfa859-53c6-493f-bb00-254e4eb758d5