Summary: Zapatalite, Cu3Al4(PO4)3(OH)9·4H2O, was first found at a small prospect north-west of Cerro Morita, 27 kilometers south-west of Agua Prieta, Sonora. It occurs in silicified and brecciated limestone with libethenite, chenevixite, beaverite, alunite, and pseudomalachite.
Zapatalite is pale (faience) blue with pale blue streak; H = 112, G = 3·016±0·026. It is soluble in cold dilute acids and decomposed by 20% KOH. Duplicate analyses on samples of about 9 and 15 mg gave CuO 27·92, 25·77%; Al2O3 20·16, 20·26%; P2O5 20·69, 22·51%; H2O 15·46, 15·79%; insol. (baryte and quartz), 15·46, 15·79%. This leads to the formula Cu3Al4(PO4)3(OH)9·4H2O.
The cell can be indexed as tetragonal with a 15·22Å, c 11·52Å, and a volume of 2669Å3. If Z = 6, empirical cell contents are Cu19·4Al22·8(PO4)17·6(OH)55·422·2H2O, and the calculated G = 3·017. Strongest lines of the powder pattern are 7·62 (10), 11·60 (10), 5·75 (7), 6·82 (7), 3·04 (5), 2·53 (5), 2·95 (4), and 2·88 (4).
Pale green in thin section with feeble dichroism in green, with ε > ω. The good basal cleavage is a length slow direction. Indices for Na-D are ε = 1·635, ω = 1·646. Usually uniaxial (—), but may be biaxial (—) with variable 2 V.
Named for Emiliano Zapata (1879–1919), a popular hero of the Mexican revolution. Type specimens to be left with British Museum (Natural History) and the University of Arizona.