Jiuquan in Gansu Province has a long history of jade development, which is known as "Grape wines in luminous wine glass". This object of this study is a river floodplain gravel of Jiuquan. On the basis of enquiring geological data and information of Gansu, the samples were observed by visualization and the specimens were studied under the polarizing microscope. The basic gemstone properties were also tested by some instruments. For further study, chemical analysis, infrared absorption spectrum and X powder diffraction were employed to analyze the mineral composition of gravel. It has been found that the type of the rock sample is serpentinized marble probably with some serpentinized ultrabasic rocks. Serpentinized marble mainly contains antigorite and carbonate, thus suitable for engraving. This type of gravel has high gemological value and economic prospects. The results of this study have some theoretical guidance and reference values for the development and utilization of the gem resources.