Hydrated CO3-Bearing Analog of Manganoeudialyte from Alkali Pegmatites of the Konder Pluton, Khabarovsk Krai

Abstract

The chemical composition, crystal structure, and infrared (IR) spectrum of a hydrated CO3-bearing analog of manganoeudialyte from alkali pegmatites of the Konder pluton (Khabarovsk krai) are studied. The chemical composition of the mineral corresponds to the formula N[Na6.94H2O5.13(Y,REE)0.58. Pb0.31K0.28Ba0.08]13.32M1[Ca5.09Sr0.89]5.98M2[Mn1.523+Ti0.21Mg0.04Fe0.033+Al0.02]1.82M3(Si1.16Nb0.47)1.63 M4(Si)0.50. Z[Zr3.04Hf0.03]3.07(Si3O9)2(Si9O27)2(CO3)0.28 X[(H2O)4.45OH0.04Cl0.03]4.52. The IR spectrum contains the following lines (s, strong; sh, shoulder): 455s, 475s, 655, 740s, 925s, 977s, 1010s, 1145, 1420sh, 1504, 1650, 2970sh, 3240sh, 3480 cm–1. The crystal structure is refined in the $$R\bar 3m$$ spatial group, a = 14.243(3), c = 30.371(6) A, and V = 5336(2) A for 1393 independent reflections (|Fo| > 4σF with a similarity factor R1 of 6.5%. The deficit in Na and Cl, the presence of Pb and Ba, and the high degree of hydration of the mineral indicates postcrystallization ion-exchange processes typical of hydrothermal alteration of aegirine–albite rocks of the Konder pluton.