The Navajo Nation moved closer Monday to taking over a coal mine on the reservation. Tribal lawmakers voted to form a limited liability company that would run the Navajo Mine near Farmington, N.M. The tribe has said it would decide by July 1 whether to purchase the mine from Australian-based BHP Billiton for about $85 million. Navajo President Ben Shelly also must approve the creation of the Navajo Transitional Energy Company, LLC. The Navajo Nation signaled its intent in December to venture into the coal mining business. The mine produces between 6.5 million and 8.5 million tons of coal each year, which goes to the Four Corners Power Plant. The plant's operator intends to shut down some of the units, which will decrease coal production.