It has been 90 years since Prof. Ding Daoheng found the Bayan Obo iron ore in 1927. Follow-up research and production show that the deposit is not just an iron ore, but world's largest rare earth and niobium deposit. Many geological experts both home and abroad have conducted numerous investigation and research. And volcanic rocks had been predicted to occur in this area. It was not until 1982 that the authors found volcanic rocks in the west mine of this area, which occur mainly in the slate surrounding iron orebodies. They are mainly composed of intermediate or acidic volcanic rock series, including dacitic breccia tuff, dacitic fused breccia, and dacite. The volcanic rocks are characterized by porphyry structure and aphanitic tuff texture. The dacite is microcrystalline structure, while feldspar and quartz phenocrysts are of well-developed microcracks. The quartz shows a harbor structure with good ablation. Secondary sides, volcanic glass and its debris also occur in the feldspar.