Mawpyut igneous suite in Jaintia Hills of Meghalaya plateau comprises differentiated suite of ultramaficmafic rocks. The complex differs from other ultramafic-alkaline-carbonatite igneous emplacements of Shillong plateau and Mikir Hills like Jesra, Sung, Samchampi complexes, by the absence of alkalinecarbonatite rocks as major litho-units. Melanite garnet-bearing nepheline syenite, occurs as late phase minor intrusion in Mawpyut igneous complex, posseses alkaline character and shows inubiquitous relation with the host ultramafic-mafic rocks. On the other hand, this alkaline intrusive bodies of the Mawpyut igneous complex shows chemico-mineralogical resemblance with garnet-bearing nepheline syenite, ijolite litho-members of Jesra, Sung, Samchampi complexes of the region. It is interpreted that melanite garnet-bearing nepheline syenite intrusion in Mawpyut is contemporaneous with Jesra, Sung, Samchampi ultramafic-alkaline-carbonatite complexes and the host rocks of Mawpyut complex is an earlier magmatic activity possibly from a comparatively least enriched source.

The alkaline plug of Nirwandh in Patchaam Island, Kutchh district, Gujarat is emplaced within the unmetamorphosed Jurassic limestone of Patcham Formation. A thin band of Tschermaks clinopyroxene (fassaite)-grandite-bearing calc-silicate occurs as skarn rock at the contact of the alkaline plug and limestone sediments. The mineralogical and textural evidences indicate that the rock is evolved by contact metamorphism due to fluid infiltration at shallower depth during very high temperature regime.

Widely variable modal mineralogy and reconstituted or hybridised character of peralkaline lamproites of Gondwana Coalfield in Eastern India demands mineralogical studies for magma genesis in petrogenetic point of view. This work reports a Ba-Fe titanate and the unnamed titanosilicate minerals that developed at the last-stage of crystallisation which characterised Ba enriched source for primary magma.

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