CARYOCHROITE IS A RARE MINERAL FROM THE GROUP OF TITANOSILICATES: CRYSTAL STRUCTURE, CRYSTAL CHEMISTRY AND THERMAL PROPERTIES

Abstract

The crystal structure of rare titanosilicate cariochroite was deternined using X-ray powder and srlected area diffraction data. The crystallochemical formula proposed – [Na(Sr0.5Ca0.5)Mg]3[Fe\(_{8}^{{3 + }}\)Mn(\({\text{Fe}}_{{0.5}}^{{2 + }}{\kern 1pt} {{\square }_{{{\text{0}}{\text{.5}}}}}\))]10(Ti2Si12)O37(OH)14(Н2О)3. Monoclinic unit cell parameters are: a 16.550(3), b 5.281(2), c 24.25(3) Å, β 93.0°, Z = 2, sp. gr. P2/n. The crystal structure represent the new type of complex Ti–Si–nrt, provided the big volune canals contaning some exchange cations, OH groups and water molecules.