The discovery was made in China's Xinjiang Uygur Autonomous Region, the country's state-run Xinhua News Agency reported Tuesday.
The gold deposit in Xinyuan County in the Ili Valley is estimated to contain at least 53 tons, Zeng Xiaogang, head of the region's geology and mineral resources bureau, said.
The gold-bearing region reportedly stretches for almost 2 miles at depths of 200-1,000 feet.
It is also estimated to hold 31,000 tons of copper, Zeng said.
A mining group has spent 5 years and $24 million to find the reserves, which it hopes to begin mining by the end of 2015, he said.
It is the second large gold reserve discovered in the Ili Valley; one containing 50 tons was found in 1988, Zeng said.