Greencastle Resources Ltd., together with its subsidiaries, engages in the exploration and development of gold, base metal, oil and gas properties, and royalties in Canada. The company operates through Investments in Private and Public Companies; Oil and Gas Interests; and Mining Interests segments. It holds interests in the Jewel Ridge gold property located in Nevada, the United States; the Primate oil and gas property in Saskatchewan; and the Ferrier oil and gas project located in Alberta. The company also holds royalty interests in wells located in the Spirit River area, Alberta. Greencastle Resources Ltd. was founded in 1996 and is headquartered in Toronto, Canada.