Situated between Iskou (No. 121-00-014) and Egalah (No. 121-00-012) Aroyan consists of an amphibole-biotite granite of alkali feldspar, quartz, ferrohastingsitic and arfvedsonitic amphiboles, hedenbergite and biotite. Rhyolite dykes occur in the centre of the intrusion. Igneous activity continued on the northern side of the intrusion in the form of the massif of Azambaradan-Tamoelet (Black et al., 1967) which is joined to Aroyan by dykes of microgranite. This occurrence is composed of amphibole-biotite, biotite and microcline-albite-riebeckite granites.