X-ray powder diffraction data for botallackite

Botallackite, Cu-2(OH)(3)Cl, from the Botallack mining area in Cornwall, United Kingdom, has been reinvestigated regarding physical, optical, chemical, and X-ray powder diffraction data. It forms emerald-green tabular crystals slightly elongated along [010] with {001} (dominant), 11001, 10101, and {011}. Botallackite is biaxial positive, 2V=70(2)degrees, the optical orientation is Y boolean AND c 22(2)degrees (in obtuse beta), Z=b. Electron-microprobe analyses gave CuO 73.26, ZnO 0.22, Cl 16.80, H2O (calc) 12.37, total 102.65, less O=Cl 3.79, total 98.86 wt %, corresponding to the empirical formula Cu1.99Zn0.01(OH)(2.97)Cl-1.03 (based on four anions). Unit cell parameters refined from X-ray powder diffraction data are a 5.7155(5), b 6.1255(6), c 5.6336(4) angstrom, beta 93.090(8), V 196.95(2) angstrom(3), Z=2. (c) 2006 International Centre for Diffraction Data.