The Cordon Syenite Complex (Punongbayan, 1974) is situated in the eastem foothills of the Cordillera Central, just east of the provincial boundary between Nueva Vizcaya and Isabela. The syenitic rocks crop out in a belt running from Magat River to Highway No, 5. The Cordon Syenite Complex is a multiple intrusion formed through successive intrusions of syenitic magmas, and finally intruded by monzonites which brought about copper mineralization. Baquiran (1975) calls the monzonites trachyandesites thus emphasizing the fine-grained nature of their matrix, although this characteristic is typical of porphyry copper ore deposits.