Chinese police have launched a violent tear-gas assault on Tibetan villagers in Qinghai's Yulshul prefecture, ending a two-month protest against suspected mining operations on local mountains, according to a local source. On July 7, around 100 local Tibetans had gathered at a place called Upper Dechung, where Chinese mining operations were under way, a resident of the area told RFA's Tibetan Service on Wednesday. "The protesters were willing to put themselves at risk to stop the mining, but the Chinese police were called in to disperse the crowd, using tear gas," RFA's source said, speaking on condition of anonymity. Many protesters were left unconscious in the attack, while others were severely beaten by police, RFA's source said. "Among them was a 70-year-old man called Sogrui Pewang, who had to be rushed to a hospital to be treated for his injuries," the source said. Fearing further threats from Chinese police forces in the area, around 50 to 60 local residents left that evening to ask provincial authorities for their help and protection, but have not been heard from since, RFA's source said. "Mining has taken place here off and on, and the Chinese told us about a year ago that they were going to build a road through the area, but the local Tibetans began to suspect that the Chinese were digging not to build a road, but a mine." The mining at Upper Dechung is not being carried on by the Chinese government, but by local officials with the collaboration of "other persons in the county," RFA's source said. "Local people suspect corruption is involved in connection with this joint venture," he said. Tibet has become an important source of minerals needed for China's economic growth, and Chinese mining operations in Tibetan areas have led to widespread environmental damage, including the pollution of water sources for livestock and humans and the disruption of sacred sites, experts say.