Abstract: Features and Genesis of The Light-green Mudstones of Longtan Formation in Shuicheng Mining Aaea——In the cower of the second section of Longtan formation there are two light-green mudstones (clayey tuff) with evident features and stable distribution. The Combining study using macroscopic and microscopic examination, Chemical, differeatial theamal nad X-diffraction analysis indicates that the muds-tones were formed composed of volcanic materials ceposited in marsh and coastal larkes. The mudstones Can be used as reliable marker for seam Correlation in the mining area and the region.