GORDAITE, NAZN4(SO4)(OH)(6)CL-CENTER-DOT-6H(2)O, A NEW MINERAL FROM THE SAN-FRANCISCO MINE, ANTOFAGASTA, CHILE

Gordaite, a new hydrous sodium zinc hydroxy-chlorosulfate, ideally NaZ n4(SO4)(OH)(6)Cl . 6H(2)O, Z = 2, is trigonal, space group P (3) over bar, with a = 8.3556(3) Angstrom, c = 13.025(1) Angstrom, from single crystal studies. The strongest reflections in the X-ray powder diffrac tion data are (d(meas.),I,hkl) 12.950(100) (001), 6.501(23) (002) and 4.339(15) (003). The mineral occurs at the San Francisco Mine, Sierra Gorda, northeast of Antofagasta, Chile. It forms masses of white to co lorless platy crystals. Electron microprobe and CHN analyses yielded N a2O 9.15, ZnO 52.85, SO3 15.33, Cl 6.46, H2O 12.33. Gordaite is probab ly identical with an unnamed mineral (ICDD-PDF 41-1421) which has been found on sulfide samples from the Juan de Fuca Ridge, NE Pacific.