This study aims to determine the process of the formation of Batu Angus and the type of Batu Angus on the East Slope of Mount Gamalama Ternate Island, North Maluku. This research is a type of qualitative research that reveals how the process of the formation of Batu Angus and the types of rocks of Batu Angus Mount Gamalama. The research data was collected through interviews, observations, and petrographic laboratory analysis. The research data were analyzed using a polarization microscope to determine the type of Batu Angus Mount Gamalama. The results showed that the process of Batu Angus formation on the eastern slope of Mount Gamalama was initiated by an effusive volcanic eruption in 1907 in the form of lava flowing down the slope which took place in the northeast part of Mount Gamalama and piled up in the Kulaba village. Based on the results of the petrographic analysis in the laboratory, it was obtained the results that Batu Angus contained Plagioclase minerals, Pyroxene, Opaque minerals, and Glass minerals, so that it can be concluded that Batu Angus is one of the Andesite Pyroxene igneous rocks.