Abstract:Composed mainly of secondary quartz (50%~90%) and pyrite and minor realgar, orpiment, barite, illite as well as dickite, siliceous rocks are often characterized by typical hydrothermal metasomatic texture and metasomatic relict texture, and typical tectonite structures such as bracciated structure,cataclastic structure, porphyroclastic structure and small fissure and pore structures, with no sedimentary structures and textures. Gold-bearing or silver-bearing siliceous rocks are produced by silicification during mineralization. Undermicroscope, the silicification consists of 3 stages in the gold-forming period and 1 stage in the silver-forming period. REE compositions of the rocks show that ΣREE is especially low in silver-bearing rocks, LREE is richer than HREE in gold_bearing rocks, and MREE is rich in silver-bearing rocks. Therefore, the NASC normalized distribution curves dip towards right in gold-bearing rocks and upwards in silver-bearing rocks. In addition, the curves show slight negative ceriumanomaly and apparnt negative europium anomaly or indistinct positive europium anomaly, which differ from the curves of typical hydrothermal sedimentary chertsor sedimentary exhalation cherts with obvious negative cerium anomaly and positive europium anomaly. So the rocks should be typical jasperoid, which, instead of being formed by hydrothermal sedimentation or sedimentary exhalation between seawater and the surface of sediments, is a product of hydrothermal metasomatism.