Octanex Limited is an Australian firm dedicated to the investment, exploration,... Octanex Limited is an Australian firm dedicated to the investment, exploration, and development of natural resources, predominantly within Western Australia. Its principal holding is the Sefton gold property, located in the Eastern Goldfields of Western Australia. This significant project encompasses five granted mining tenements totaling approximately 2,105 square kilometers, complemented by an additional 480 square kilometers currently under application. Founded in 1980, Octanex Limited's corporate office is situated in South Yarra, Australia.