Summary: Quetzalcoatlite is a new mineral from the Bambollita mine in the Sierra La Huerta near Moctezuma, Sonora, Mexico. The colour is Capri blue (R.H.S. 120A) with a pale streak. H = 3; G meas. = 6·05±0·3 G calc. = 6·12. Crystals up to 0·4 mm long were not measurable but are acicular to prismatic, hexagonal, with fair cleavage on {101¯0}; a 10·097 Å, c 4·944, space group C6₃2. Z = I. Strongest lines are 8·752 (100), 2·748 (70), 2·520 (42B), 3·531 (40), 3·273 (31), 1·766 (28), 5·054 (21), 2·250 (20). Electron probe analysis gives: CuO 20·3%, 18·9, 20·9; ZnO 41·2, 38·2, 38·7; TeO₂ 29·4, 31·3, 30·6. Water by Penfield method on 2.265 mg gave 10·1%. Empirical cell contents are Cu_4·01Zn_7·73Te_3·04O_8·88(OH)_17·89 or Cu₄Zn₈(TeO₃)₃OH₁₈. Pleochroic with ε = colourless, ω = pale blue-green; uniaxial (-) with ε_D = 1·740, ω_D = 1·802. Named for the Toltec god Quetzalcoatl.