China has discovered rare metal deposits of more than 100,000 tonnes of niobium, the nation's largest of its kind, in northwest Xinjiang Uygur Autonomous Region, an engineer revealed Monday.

"The size has surpassed China's total proven niobium reserve of 80,000 tonnes," said Xu Haiming, a senior engineer with the Institute of Mineral Resources at the Chinese Academy of Geological Sciences.

"The super-large deposit is worth more than 130 billion yuan (19 billion U.S. dollars) after being exploited."

It also has a proven reserve of more than 10,000 tonnes of tantalum and rare earth metals, Xu said.

The deposit is 3,860 to 4,100 meters above sea level, in Baicheng County, Aksu Prefecture of south Xinjiang.

Niobium and tantalum are rare metal elements, which are widely used in the fields of electronics, aviation, atomic energy, and mechanical manufacturing.

The exploration started in 2007 and has cost about 20 million yuan, Xu said.