Reference:
▪ Shablinskii, A.P., Filatov, S.K., Vergasova, L.P., Avdontseva, E.Yu., Moskaleva, S.V. (2018): Wrightite, K2Al2O(AsO4)2, a new oxo-orthoarsenate from Great fissure Tolbachik eruption, Kamchatka peninsula, Russia. Mineralogical Magazine, 82, 1243-1251.
Abstract:
Wrightite K2Al2O(AsO4)2 is a new mineral species. The specimen was found in 1983 at a fumarole on the Second cinder cone of the Great fissure Tolbachik eruption. Wrightite light yellow aggregates consist of transparent tabular crystals with the average size of 0.05×0.03×0.005 mm3. Space group Pnma, a = 8.230(5), b = 5.555(4), c = 17.584(1) Å, V = 803.9(6) Å3, Z = 4, powder data. The empirical formula is (K1.69Na0.38)Σ2.07(Al1.80Fe0.24)Σ2.04As1.96O9. Crystal structure (R = 0.043) consists of Al2O(AsO4)2 layers in the ab plane with clusters of edge-sharing AlO6 octahedra. Each layer contains two independent isolated AsO4 tetrahedra and two AlO6 octahedra. AlO6 octahedra are linked by edges, forming zigzag chains along the b-axis inside the Al–As layer. Eight- and six-coordinated K atoms are located in the interlayer space between Al2O(AsO4)2 layers. The mineral is biaxial (−), α =1.679(2), β =1.685(2), γ (calc.) =1.687; 2V (meas.) = 62(10)º (delta = 589 nm). The strongest lines in the X-ray powder diffraction pattern (I-dobs. Å-hkl) are: 36-8.77-002; 17-4.458-111; 19-4.010-201,013; 19-3.875-104; 100-2.972-015. The mineral was named in honour of Adrian Carl Wright, Emeritus Professor at the University of Reading, UK.
▪ Shablinskii, A.P., Filatov, S.K., Vergasova, L.P., Avdontseva, E.Yu., Moskaleva, S.V. (2018): Wrightite, K2Al2O(AsO4)2, a new oxo-orthoarsenate from Great fissure Tolbachik eruption, Kamchatka peninsula, Russia. Mineralogical Magazine, 82, 1243-1251.
Abstract:
Wrightite K2Al2O(AsO4)2 is a new mineral species. The specimen was found in 1983 at a fumarole on the Second cinder cone of the Great fissure Tolbachik eruption. Wrightite light yellow aggregates consist of transparent tabular crystals with the average size of 0.05×0.03×0.005 mm3. Space group Pnma, a = 8.230(5), b = 5.555(4), c = 17.584(1) Å, V = 803.9(6) Å3, Z = 4, powder data. The empirical formula is (K1.69Na0.38)Σ2.07(Al1.80Fe0.24)Σ2.04As1.96O9. Crystal structure (R = 0.043) consists of Al2O(AsO4)2 layers in the ab plane with clusters of edge-sharing AlO6 octahedra. Each layer contains two independent isolated AsO4 tetrahedra and two AlO6 octahedra. AlO6 octahedra are linked by edges, forming zigzag chains along the b-axis inside the Al–As layer. Eight- and six-coordinated K atoms are located in the interlayer space between Al2O(AsO4)2 layers. The mineral is biaxial (−), α =1.679(2), β =1.685(2), γ (calc.) =1.687; 2V (meas.) = 62(10)º (delta = 589 nm). The strongest lines in the X-ray powder diffraction pattern (I-dobs. Å-hkl) are: 36-8.77-002; 17-4.458-111; 19-4.010-201,013; 19-3.875-104; 100-2.972-015. The mineral was named in honour of Adrian Carl Wright, Emeritus Professor at the University of Reading, UK.