Diamond-facies chrome spinel from the Tokapal kimberlite, Indrāvati basin, central India and its petrological significance

Widespread and abundant spinel is the only primary mineral of petrogenetic significance preserved in the hydrothermally altered, crater-facies, Neoproterozoic (≥620 Ma) Tokapal kimberlite pipe that intruded the Indrāvati basin, Bastar craton, Central India. Two distinct spinel populations occur: (i) finer-grained (400 μm) with cores having distinctly chromium-rich (Cr 2 O 3 up to 63.67 wt%), and TiO 2 -poor (550 ha) of kimberlite, there is a possibility that it contains diamonds but they were not recovered during the sampling. Alternately, highly oxidising conditions imparted by the metasomatic fluids/melts derived from (i) asthenosphere-lithosphere interaction, or (ii) the kimberlite itself might have played an important role in the destruction of diamond, and other indicator minerals.