Aluminum forms a number of tridecameric (Al,,) cluster compounds in which 02-, OH-, FP, and HZ0 are ligands. Examples are the basic aluminum salts (chloride, selenate, and sulfate, Refs. (1, 2)) and the m ineral zunyite (3). The basic aluminum salts are formed by partial hydrolysis of A1(H20)63’ by base, have commercial utility, and have recently been the subject of several studies using aluminum-27 NMR spectroscopy, both in solution (4, 5) and in the crystalline solid state (I, 6). The basic aluminum salts all contain a central AlO unit, surrounded by twelve six-coordinate Al atoms. Early solution NMR studies readily detected signals arising from AD4 in the tr idecamer (4), but only under certain conditions (at high temperature) could resonances attributable to the octahedral aluminums be observed, due presumably to their large quadrupole coupling constants (e2qQ/h). Similarly, detection of the octahedral aluminums in the basic chlorides and sulfates in the solid state has until now not been successful (6). In contrast, solid state NM studies using “mag ic-angle” sample spinning (MASS) (7) of the m ineral zunyite, a basic aluminum silicate having the structure [Ali,(OH, F)i6F2]Si502&1, have recently revealed quite narrow lines for both fourand six-coordinate aluminum (I). In this paper, we present 27A1 MASS, variable-angle sample-spinning (VASS) (8) and static NMR spectra of basic aluminum selenate, sulfate, and the m ineral zunyite, obtained at several magnetic field strengths, which has allowed us to determine e2qQ/h and isotropic chemical-shift values for both Al(4) and Al(6) sites in all three systems. We discuss the likely origins for the large differences in e2qQ/ h between Al(6) sites in zunyite (-2.5 MHz) and the basic aluminum selenate and sulfate (10 MHz). Availability of e*qQ/h (and asymmetry parameter, 7) information will be shown elsewhere to permit evaluation of rotational correlation times for the Ali3 clusters in solution, and thereby to permit estimation of oxygen-l 7 e’qQ/h values in such systems (9). The basic aluminum selenate and sulfate were obtained as Na[AI04 a Ali2(OH)24(OH2)12] (X0&.YH20 (X = Se or S and Y 13, Ref. (2)) from