The collapse on Wednesday at an open-pit mine in the Alxa League operated by Xinjing Coal Mining Co left a pile of debris roughly 500 m (550 yards) across and an estimated 80 m high, state media reported, Reuters reported.
"I had just started work at 1:15 in the afternoon when I realized that rocks were falling from the mountain," a hospitalized miner told state broadcaster CCTV on Thursday.
"I saw that the situation was getting more and more serious, and an evacuation was organized, but it was too late, the mountain just collapsed."
President Xi Jinping on Wednesday ordered search and rescue efforts, state media reported, although a second landslide in the evening hampered the work to find survivors.
"We must make every possible effort to rescue the missing persons and treat the injured," Xi said.
Premier Li Keqiang also demanded a quick investigation into the cause of the collapse.
RHM/PR