Nine Native American tribes in South Dakota, North Dakota and Nebraska are suing the federal government in a bid to stop exploratory drilling for graphite near a sacred site in the Black Hills . A small group of demonstrators has been protesting at the drilling location and at the mining company's headquarters since they learned ground was broken on the drilling project in late April. The tribes filed their federal lawsuit Thursday in South Dakota against the U.S. Forest Service and U.S. Department of Agriculture, alleging that the agencies violated federal law by greenlighting a project near a site called Pe’Sla, a meadow in the central Black Hills used for tribal ceremonies, prayer and youth camps year-round. The project is the latest point of tension between tribes and mining interests in the lush pine-covered Black Hills, which encompass over 1.2 million acres (485,000 hectares), rising from the Great Plains in southwest South Dakota and extending into Wyoming.…