A detailed mineralogical examination of representative material from the P2-West 'kimberlite' located in the Wajrakarur Kimberlite Field (India) demonstrates that significant differences exist between these rocks and archetypal hypabyssal kimberlite. The intrusion consists of an olivine-phyric facies which has been transected by, and includes clasts of, a consanguineous phlogopite-rich pegmatitic facies. The olivine-rich parts of P2-West are relatively fresh and consist of euhedral-to-subhedral microphenocrystal olivine set in a groundmass of fine-grained anhedral monticellite, amoeboid apatite, and subhedral-to-euhedral perovskite within a partially chloritized-to-fresh phlogopite-rich mesostasis. The rock lacks the abundant olivine macrocrysts characteristic of kimberlite. Monticellite crystals are commonly partially or completely replaced by pectolite and hydrogarnet. Similar material occurs as irregular aggregates randomly scattered throughout the groundmass. The groundmass, in contrast to that of hypabyssal kimberlites, is relatively poor in spinels. Atoll spinels are absent, with the majority of spinels occurring principally as mantles upon microphenocrystal olivine. Disaggregated cumulate-like assemblages of intergrown anhedral perovskite and spinel are common. Spinel compositions are unlike those of kimberlites and their evolutionary trend is similar to that of lamproite and lamprophyre spinels. The pegmatitic facies of the intrusion are highly and pervasively altered, and characterized by the presence of large clasts, veins, and irregular aggregates consisting of large (1–5 mm) crystals of pinkish-bronze Al-poor phlogopite intergrown with and/or including: apatite; pectolite-hydrogarnet pseudomorphs after an unidentified euhedral phase; chlorite laths; barytolamprophyllite; perovskite; tausonite; diverse Sr-Ba-carbonates; and baryte. The presence of barytolamprophyllite and tausonite are typical of potassic undersaturated alkaline rocks and have never been reported from kimberlite; however, neither feldspar nor feldspathoids are present in P2-West. Micas in fresh and altered rocks are Al2O3- and BaO-poor, and exhibit compositional evolutionary trends towards tetraferriphlogopite rather than kinoshitalite. On the basis of these mineralogical data it is suggested that P2-West represents an unusual lamproite-like intrusion which has undergone extensive hydrothermal deuteric alteration and should not be considered a bona fide kimberlite.

Tausonites occurring in aegirine potassium feldspar syenite from the Little Murun potassic alkaline complex are characterised by complex growth and resorption features. These are attributed to nonequilibrium crystallisation in a dynamic environment characterised by magma mixing and/or volatile degassing. The crystals represent a transported assemblage which has no simple relationship to the magma from which their host rock crystallised. Tausonites exhibit significant normal, reverse and oscillatory compositional zoning with respect to strontium and the rare earth elements. The compositions are unique, ranging from tausonite to strontian cerian loparite, and are unlike those found in strontian perovskites from lamproites and fenites associated with carbonatites.

Compositional data are presented for Ba-rich titanates belonging to the hollandite group, Ba(Ti,Fe)5O11 and K2Ti13O27. The titanates, on the basis of textural evidence, are interpreted to have formed by the reaction of K-Ba-rich residual liquids with pre-existing Ti-magnetite, ilmenite and tausonite. The compositions of the titanates are similar to those of primary titanates found in kimberlites and carbonatites.