Xocomecatlite, Cu3TeO4(OH)4, and tlalocite, Cu10Zn6(TeO3)(TeO4)2Cl(OH)25·27H2O, two new minerals from Moctezuma, Sonora, Mexico

Abstract

SummaryXocomecatlite and tlalocite were found at the Bambollita mine near Moctezuma, Sonora. Xocomecatlite is probably orthorhombic, and an indexed cell based on the powder data gave a 12.140 A, b 14.318, c 11.662. Based on this cell, the empirical contents are Cu36.6 Zn1.7 (TeO4)12.5 (OH)51.6 or Cu3TeO4(OH)4. Tellurate was found both microchemically and by spectrophotometry. Colour rich green (R.H.S. 132A) with pale streak, H = 4. Optically negative with α = 1.775, β = 1.900, γ = 1.920. G = 4.65.Tlalocite is optically orthorhombic but the cell could not be indexed; only powder data are presented. Chemical analysis showed both tellurite and tellurate and led to the formulaColour pale blue (R.H.S. 121A) with a whitish streak; H = 1, gummy and sectile. G = 4.55.Plotting stability fields for various Te species at 25°C in terms of Eh and pH showed that TeO42−.aq can exist in nature over a wide pH range, but only under extreme conditions of oxidation.