Greencastle Resources Ltd. engages in the exploration and development of gold, base metal, oil and gas properties, and royalties. The company operates through Investments in Private and Public Companies; Oil and Gas Interests; and Mining Interests segments. It holds interests in two oil and gas properties, which include Primate and Primate North projects located in Saskatchewan; and the Ferrier project located in Alberta, Canada.

The company also holds interests in the Jewel Ridge project and the Indian Creek project located in Nevada; and the Mayflower property consists of 64 claims located in the northwestern Ontario. In addition, it has an option agreement to earn 100% interest in the Seagrave property consists of 131 claim units located in the Birch-Uchi Greenstone Belt, Red Lake Mining Division in northwestern Ontario. The company was founded in 1996 and is headquartered in Toronto, Canada.