pinakioliteMin.|pɪˈnækɪəʊlaɪt| [mod. (Flink, 1890) f.Gr. πινάκιον, dim. of πίναξ tablet + -lite.] Borate of manganese and magnesium, found in brilliant black tabular crystals. 1891Amer.Jrnl.Sc.Ser. iii. XLI. 251 Pinakiolite is a new borate of manganese and magnesium.