The origin of Al-rich spinel inclusions in leucite from the leucite lamproites of Western Australia.

Aluminous spinels (pleonaste-hercynite) occur as tiny (mostly <20 mu m) inclusions in leucite phenocrysts (and pseudomorphs) in leucite lamproites from the West Kimberley region, Western Australia. Their formation in these peralkaline volcanics is attributed to exsolution under conditions of supersaturation from non-stoichiometric leucites originally incorporating Mg, Al and Fe²⁺ in solid solution. -J.A.Z.