gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1980.043.329.12 Apachite and Gilalite, Two New Copper Silicates from Christmas, Arizona Cesbron F. P. Laboratoire de Minéralogie-Cristallographie, place Jussieu, 75230 Paris Cedex 05, France Williams S. A. Box 872, Douglas, Arizona 85607, USA 3 1980 43 329 639 641 29 9 1979 Copyright © 1980, The Mineralogical Society 1980 Summary

Both new species are retrograde or mesogene minerals that occur in tactites at the Christmas mine, Gila County, Arizona (USA). Gilalite is green, H = 2, D = 2.82. Biaxial (—), 2V small, α = 1.560, β = γ = 1.635. No single crystals found; strongest lines at 13.49 Å, (10); 10.97 (5); 7.786 (5). Analysis gave CuO 36.2%, MgO 2.3, CaO 3.8, MnO 0.5, SiO2 41.5, H2O 14.6, close to Cu5Si6O17·7H2O.

Apachite is blue, H = 2, D = 2.80. Biaxial (—), 2V small, α = 1.610, β = γ = 1.650. No single crystals found. Strongest lines are 12.90 Å (10); 3.168 (7); 7.663 (5). Analysis gave CuO 43.6%, FeO 0.3, MgO 1.7, CaO 1.8, SiO2 40.8, H2O 13.8, close to Cu9Si10O29·11H2O.