A new coal interface detection method is under investigation by the U.S. Bureau of Mines. This novel concept is based on utilizing a passive infrared system (pir) to measure temperature changes associated with the cutting of coal and adjacent strata. For this method to work successfully, a definite mechanical-hardness contrast must exist between coal and rock. Advantages include that pir responds instantaneously at the coal-rock interface and is minimally affected by dust and/or water sprays. Based on preliminary tests, results indicate that the pir method can be applied successfully in mines having a hard immediate roof.