Imenite is a diamond-associated mineral. In kimberlites, ilmenite occurs as megacrysts and macrocrysts (monomineral nodules), as well as phenocrysts within a fine-grained groundmass. The chemical compositon of ilmenite from kimberlites is characterized by high contents of Cr, Nb, and Zr. Large grains sometimes demonstrate wavy extinction and a «mosaic» structure, indicating the influence of deformation processes after crystallization. Ilmenite is also found in lithospheric mantle rock ranges from 1.5% (Udachnaya pipe, center of Siberian craton, Yakutian kimberlite province) to 4-7% (Obnazhennaya pipe, northeastern margin of the craton). Ilmenite has a variety of morphologies. In the Mir and Obnazhennaya pipes, this mineral occurs as small, rounded, and elongated inclusions (up to 20-50 μm in size) in garnet and clinopyroxene, as well as needles and lamellae (up to 20-40 μm thick), following the crystallographic orientation of the host mineral. These are presumably exsolution structures. Lamellas show a wide range of chemical compositions, from 39.7 to 57.6 wt.% TiO2 and 4.2-12.5 wt.% MgO. Large variations in the compositions of ilmenite lamellas from pyroxene and garnet crystals suggest that these ilmenites formed as exsolution structures during the gradual cooling of initial pigeonite megacrystals. Ilmenite from mantle rocks forms relatively large (0.3–2 mm) isometric grains with thin elongations parallel to the banding and lenticular porphyroclasts with features of mosaic polygonality, indicating the initial stage of rock deformation. Thus, ilmenite from kimberlite xenoliths in the central Siberian Craton occurs in polymictic breccias and exsolution structures in other minerals and is predominantly of cumulative origin. Ilmenite from mantle xenoliths from northeast of Yakutia has a variety of morphologies, which allows us to distinguish several generations and indicates a multi-stage genesis and heterogeneous lithospheric mantle beneath the shallow northeastern margin of Siberain craton.