Kayupovaite, ideally Na2Mn10[(Si14Al2)O38(OH)8]·7H2O, is a new mineral named in honor of Dr. Maria Mikhailovna Kayupova (1921-1980), the mineralogist of Satpaev Institute of Geological Sciences (Alma-Ata, USSR) who studied the Ushkatyn-III complex baryte-lead / iron-manganese deposit, Karagandy Province, Kazakhstan, the type locality of the described mineral. Kayupovaite forms coarse lamellar (typically bent and split) light grey with greasy luster crystals up to 0.2 × 0.15 × 0.01 mm combined into radial, scaly or lamellar aggregates up to 3 × 3 × 0.5 cm embedded in a calcite - rhodonite matrix. Optically, in transmitted light kayupovaite is colourless, with undulatory extinction due to crystal curvature, non-pleochroic, biaxial (–), α 1.551(4), β = γ 1.586(2), 2Vmeas = 3±1 °. Kayupovaite is monoclinic, space group C2/c, a = 24.9149(9), b = 16.4343(5), c = 22.3974(7) Å, β = 94.408(3) °, V = 9143.7(5) Å3, Z = 8. The strongest lines of powder X-ray diffraction pattern (d in Å (I) (hkl)): 12.34(100)(200), 3.45(8)(71-1), 3.09(8)(800), 2.85(100)(121), 2.5946(12)(714), 2.642(11)(354), 2.614(7)(40-8), 2.414(7)(554). The Raman spectrum of kayupovaite contains the following bands (cm-1): 3635, 3560 (O – H stretching vibrations of OH groups and H2O molecules); 1041, 768, 742, 717 (Si – O and Al – O stretching modes); 657, 532, 499, 460, 405, 374, 333 (Mn – O stretching and Si – O – Si modes); 304, 291, 224, 157, 100 (lattice modes). The absorption bands of the infrared spectrum are (cm-1): 3629, 3511, 3390 (O – H stretching vibrations of OH groups and H2O molecules); 1640 (H2O bending vibrations); 1020 (Si – O stretching vibrations); 778 (IVAl – O stretching vibrations); 724 (Mn – O – H bending mode); 651 (O – Si – O bending mode); 459 (Mn2+ – O stretching vibrations). The empirical formula of kayupovaite calculated on the basis of (O + OH) = 46 atoms per formula unit is (Na0.91K0.46Ca0.14)1.51(Mn2+9.29Mg0.89Zn0.02)10.20[(Si14.28Al1.61)15.89O38(OH)8]∙7.23H2O. The mineral belongs to the group of modulated manganese phyllosilicates and is structurally related to stilpnomelane. The absence of iron in the mineral is a result of oxidative Mn / Fe fractionation during the formation of braunite-rich Mn ores.
