* Four eastern Kentucky mines idled, 200 staff on furlough
* Third-quarter loss $0.73 per share vs year-ago loss $0.59
* Shares down in premarket trading
Nov 7 (Reuters) - James River Coal Co said it idled four mines in eastern Kentucky in Central Appalachia and temporarily laid off about 200 employees as coal prices fall further.
James River Coal shares were down about 0.5 percent in trading before the bell, after the coal miner reported a slide in shipments and a bigger loss for the third quarter.
The idling brings to seven the number of James River Coal mines shut since September, as U.S. coal miners suffer a double whammy of weak coal prices and tougher environmental regulations.
Thermal coal prices have been hit as power companies opt for cheaper natural gas to generate electricity, while weak steel demand and excess supplies have weighed on price of steel-making or metallurgical coal.
Miners have also been hit by the Obama administration's crackdown on emissions from coal-fired power plants.
James River Coal shares have nearly halved in value this year.
The company, which also has mines in southern West Virginia and southern Indiana, said it was hopeful that the four mines idled at its Buckeye complex could be reopened in the first half of next year.
In September, James River Coal idled production at three mines in Central Appalachia, and last month said about 525 employees, who were put on furlough, will be laid off in the fourth quarter. ()
Shipments in the third quarter fell 34 percent to 2.1 million tons, while coal prices fell about 18 percent to $68.68 per ton.
The company's net loss widened to $25.5 million, or 73 cents per share, in the third quarter ended Sept. 30, from a loss of $20.6 million, 59 cents per share, a year earlier.