The turquoise deposits in China are mainly distributed in Hubei, Henan and Shaanxi provinces, among which Baihe county, Shaanxi is one of the most important turquoise deposits. The yellow and green associated minerals collected from Xiaodonggou turquoise deposit in Baihe County, Shaanxi Province, were studied by a microscope, X-ray powder diffraction, infrared, and Raman spectroscopy. The results showed that samples were composed of alunite, and a small amount of hotsonite and kaolinite. Different shades of alunite were observed via microscope, suggesting different mineralization periods. The backscattering images showed that alunite formed later were well-developed particles with the typical false cube-like rhombohedron shapes. The infrared spectra of alunite had the bands related to PO3-4/SO2-4 in the range of 3 697~3 488 and 1 638~433 cm-1, with additional bands at 3 697 and 3 620 cm-1 attributed to the hydroxyl group of kaolinite. The Raman spectra of green samples were characterized by SO2-4 of alunite. Moreover, the peaks of OH stretching vibration in kaolinite appeared at 3 700 and 3 626 cm-1. It was assumed that the alunite veins in this turquoise deposit are formed in low temperatures and a rich alkaline environment as the deposit was of weathering and leaching origin. When the essential components derived from ore-bearing solution or surrounding rock are insufficient to produce turquoise, alunite was preferred to be formed, occurring as veins and massive and associated with hotsonite and kaolinite. This paper provided valuable information on the origin of turquoise deposits.