1 Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;
2 Department of Earth & Planetary Sciences, Hiroshima University, Higashi Hiroshima City, Hiroshima 739-8526, Japan;
3 Department of Earth Sciences and Environmental Engineering, Central South University, Changsha 410083, China
 4 The Kyushu University Museum, Kyushu University, Kakozaki, Fukuoka 812-8581 Japan;
5 Photon Factory, National Laboratory for High Energy Physics (KEK), Oho 1-1, Tsukuba, Ibaraki 305, Japan

Chenguodaite, approved by IMA-CNMMN (2004-042a), was discovered in the Bunan quartz vein-type gold deposit in the gold district of East Shandong Peninsula. The mineral occurs in high grade Au-Ag-Cu ores, coexisting with galena, chalcopyrite, hessite, electrum, unnamed Ag₆TeS₂ and Ag₁₆FeBiTe₃S₈, enclosed and replaced by native silver and acanthite. In the reflected light microscope, the mineral has light gray color, indistinguishable anistropism and hardness around 2―3. The color indices of chenguodaite relative to ICE C illuminator are: x=0.3027, y=0.3076, Y=25.78%, λ_d=474 nm, Pe=3.68%, similar to those of canfieldite. The average chemical composition from 16 microprobe analyses is Ag_8.97Fe_1.00Te_1.99S_4.04, idealized to Ag₉FeTe₂S₄. The polycrystalline X-ray diffraction of chenguodaite by Gandolfi camera and synchrotron oscillation photography results in 67 reflections with the 12 strongest being (relative intensity in bracket): 6.742(69), 6.416(39), 5.951(33), 3.265(100), 2.981(24), 2.649(22), 2.25(24), 2.188(71), 2.142(22), 2.123(31), 2.044(23), 1.949(33), which are indexed to a primitive orthorhombic cell with a=12.769 (2) Å, b= 14.814(2) Å, c= 16.233 (1) Å, V= 3070.6 ų, Z = 9, Dcal.=6.85 g/cm³. The name is for the late Prof. Chen Guoda, a famous Chinese geologist and the founder of Diwa-Geodepression theory of tectonics.

Supported by National Natural Science Foundation of China (Grant No. 40572027)