A natural mineral, lindgrenite Cu_3(MoO_4)_2(OH)_ 2 , was synthesized from a mixture of sodium molybdate, copper sulfate, and morpholine in water under autogenous pressure at 170 ℃. The crystal structure of the mineral was determined and the final refinement for 791 observed reflections with I>2σ(I) gave R_1=0.0205 and wR_ 2 =0.0496. The thermal stability of the mineral was investigated by using TG-DTA and variable-temperature in situ X-ray diffraction(XRD) techniques. The crystalline Cu_3Mo_2O_9 was obtained when the mineral underwent thermal dehydration at a temperature ranging from 300 to 400 ℃, and the mixture of MoO_3 and CuO was formed through decomposition of Cu_3Mo_2O_9 at a temperature ranging from 650 to 700 ℃. Therefore, the structure of the mineral was thermally unstable at above 300 ℃, suggesting that Lindgrenite was likely formed via the hydrothermal route occurring in the nature. A natural mineral, lindgrenite Cu_3 (MoO_4) _2 (OH) _2, was synthesized from a mixture of sodium molybdate, copper sulfate, and morpholine in water under autogenous pressure at 170 ° C. The crystal structure of the mineral was determined and the final refinement for 791 observed reflections with I> 2σ (I) gave R_1 = 0.0205 and wR_ 2 = 0.0496. The thermal stability of the mineral was investigated by using TG-DTA and variable-temperature in situ X-ray diffraction (XRD) techniques. The crystalline Cu_3Mo_2O_9 was obtained when the mineral underwent thermal dehydration at a temperature ranging from 300 to 400 ° C, and the mixture of MoO_3 and CuO was formed through decomposition of Cu_3Mo_2O_9 at a temperature ranging from 650 to 700 ° C. Thus, the structure of the mineral was thermally unstable above 300 ℃, suggesting that Lindgrenite was likely formed via the hydrothermal route occurring in the nature.