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[Na_6.94H₂O_5.13(Y,REE)_0.58. Pb_0.31K_0.28Ba_0.08]_13.32^M1[Ca_5.09Sr_0.89]_5.98^M2[Mn_1.52³⁺Ti_0.21Mg_0.04Fe^0.033+Al_0.02]_1.82^M3(Si_1.16Nb_0.47)_1.63 M₄(Si)_0.50. ^Z[Zr_3.04Hf_0.03]_3.07(Si₃O₉)₂(Si₉O₂₇)2(CO₃)_0.28 X[(H₂O)_4.45OH_0.04Cl_0.03]_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) Å, and V = 5336(2) Å for 1393 independent reflections (|F_o| > 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.