RICHMOND, Va. — James River Coal Co. is laying off 525 full-time employees and shutting down production at several mines in eastern Kentucky due to continued weak coal markets.The Richmond-based company said Monday night the layoffs occurred at operations at the McCoy Elkhorn complex in Pike and Floyd counties, the Bledsoe complex in Leslie and Harlan counties, and the Long Branch Surface mine in London, Ky.James River says the restart of the operations is subject to market conditions.The company mines thermal coal for power generation and metallurgical coal used to produce steel. It also has operations in southern West Virginia and southern Indiana.The company also idled several mines and reduced production at others in March.