High-temperature larnite rocks are abundant at Hatrurim Basin, Israel (combustion metamorphic Hatrurim Formation). Perovskite, brownmillerite and two intermediate phases were found in these rocks. It is a first occurrence supporting the existence of the perovskite-brownmillerite pseudobinary series in nature. Perovskite contains up to 18 mole % of the Ca2(Fe,Al)2O5 end-member, while brownmillerite is rich in the CaTiO3 end-member up to 15 mole %. Intermediate phases correspond to Ca3Ti(Fe,Al)2O8 and Ca5Ti(Fe,Al)4O13 and have synthetic analogous. It was found that perovskite and brownmillerite never coexist within particular larnite rock and instead of them Ca3Ti(Fe,Al)2O8 may appears as stable and sole phase of the series. The associations of intermediate phase with either perovskite or brownmillerite are most common for the Hatrurim larnite rocks.