Esperanzaite, NaCa2Al2 (As(5+)O4)2F4(OH)2H2O, a new mineral species from the La Esperanza Mine, Mexico; descriptive mineralogy and atomic arrangement - Foord, E.E.; Hughes, J.M.; Cureton, F.; Maxwell, C.; Falster, A.U.; Sommer, A.J.; Hlava, P.F. (Canadian Mineralogist, 1999)