Abstract:Parnauite was first discovered in the United States in 1978. In China, it was first found in the Debao ore district of Guangxi in 1984. There are two forms of parnauite in Debao: foliated and fibrous. Chemical compositionof the foliated parnauite is given as follows (in percentage): CuO 56. 09, As2O518. 39, Al2O30. 21, FeO 0. 40, SiO20. 56, SO35. 20, CO23. 83, H2O+14. 40, totally 99. 08, suggestingan ideal chemical formula of Cu9(AsO4)2(SO4) (CO3) (OH)8·6H2O, which is somewhat different from that of parnauite fromtheUnitedStates; nevertheless, the compositionof the fibrousparnauite issimilar to that of parnauite from the United States. The foliated parnauite is jade green to greyish in color, and transparent, glassy to pearly in luster.H=2,Dm=3. 33,Dc=3. 35, biaxial negative. Refractive indicesNp=1. 709,Nm=1. 732,Ng=1. 738; 2V=54. 63°. The strongest lines in X-ray diffraction pattern of the foliated parnauite are 14. 85 (100), 10. 45 (15), 7. 20 (10), 6. 46 (12),4. 55 (60), 4. 03 (20), 2. 867 (17), 2. 818 (10). Orthorhombic system, space groupP2122, cell dimensionsa=14. 92°A,b=14. 28°A,c=6. 02°A, calculated cell dimensionsa=15. 052 (18)°A,b=14. 320 (7)°A,c=6. 002 (6)°A,Z=2.