Austinite and adamite are secondary arsenate minerals, which were discovered for the first time in ore caves of the No.98 gold vein oxidized zone within the Laodonggou gold deposit, In ner Mongolia.Austinitemostlyoccursassubhedraloreuhedraltransparentcrystals1 . 0×0 . 8 —4.0×3.0 mm in size, with the color being green or greenish; its calculated specific gravity is 4.32. Adamite occurs commonly as transparent aggregates or crystal 1.8×1.5—3.5×2.5mm in size, with the color being light yellow-green or colculess; its caloulated specific gravity is 4.44. Studies under microscope give the following optidal characteristics:Ng=1.778,Nm=1.760,Np=1.756, positive optical character of biaxial crystal, with optic angle of 46°for austinite, and Ng=1.761,Nm=1.738,Np=1.719, positive optical character of biaxial crystal, with optic angle of 87°for adamite. Chemical analysis (wt %) shows that the composition of austinite is CaO 21.57, ZnO 29.61, CuO 2.29, MnO 0.002, Fe2O30.02, As2O5 43.07, CO20.43 and H2O+3.68, making up a chemical formula of Ca0.99(Zn0.94Cu0.07)1.01 [(AsO4)0.97(CO3)0.03]1.00(OH), and that the composition of adamite is ZnO 56.18, CuO 0.46, PbO 0.13, Fe2O30.004, As2O539.89 and H2O+3.31,making up a chemical formula of (Zn1.97Cu0.02)1.99(AsO4)(OH). As is detected by infrared spectral analysis, austinite contains minor CO2, and this is different from the feature of austimite reported by D. Radciffe et al. (1971). According to X-ray diffraction analysis, the unit cell parameters are a=0.7473nm,b=0.9017nm,c=0.5916nm for austinite and a=8304nm,b=0.8516nm,c=0.6054nm for adamite, respectively. The main ore mineral assemblage of the vein oxidized zone is scorodite+limonite+austinite+adamite+native gold+native silver+quartz+calcite+opal. The result of the study shows that adamite and austinite may be crystallized from acid to neutral solution under oxidation condition; nevertheless, the former is crystallized only when the solution has relatively high zinc ion activity. As these two arsenate minerals are of indication significance, their discovery contributes to the prospecting for secondary leaching type gold deposits.