data_global _chemical_name_mineral 'Magnocolumbite' loop_ _publ_author_name 'Pagola S' 'Carbonio R E' 'Alonso J A' 'Fernandez-Diaz M T' _journal_name_full 'Journal of Solid State Chemistry' _journal_volume 134 _journal_year 1997 _journal_page_first 76 _journal_page_last 84 _publ_section_title ; Crystal structure refinement of Mg Nb2 O6 columbite from neutron powder diffraction data and study of the ternary system MgO-Nb2O5-NbO, with evidence of formation of new reduced pseudobrookite Mg5-xNb4+xO15-d (1.14