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The pollucite structure is considered as a candidate ceramic crystalline matrix for the ceramic immobilization and long-term storage of ¹³⁵Cs and ¹³⁷Cs fission products, and thus, their structural characteristics have particular importance. However, its local structure has not been fully resolved from reciprocal-space techniques and infrared spectroscopy, and important discrepancies exist in the available literature. Two birefringent and non-stoichiometric pollucite specimens from <i>Tanco</i> pegmatite (Cs_0.83Na_0.20Al_1.13Si_2.56O₆) and from <i>Mt. Mica</i> pegmatite (Cs_0.94Na₀₁₈Al_1.23Si_2.78O₆), with powder X-ray diffraction patterns fully consistent with the cubic <i>I</i>a-3d space-group symmetry, and with a very different degree of hydrothermal alteration, were used in this work. High-resolution magic-angle spinning multinuclear magnetic resonance (MAS NMR) spectroscopy, including ²⁹Si, ²⁷Al, ²³Na, ¹³³Cs, and ¹H spectra at 9.4 T, as well as ¹H, ²⁷Al, ²⁷Al{¹H} dipolar evolutions and ²⁷Al{²⁹Si} Heteronuclear Multiple Quantum Coherence (HMCQ) spectra at 17.6 T, has been used to investigate the local structure of pollucite and the role of protons. The ²⁹Si spectra suggest a local structure with a disordered Si/Al distribution in only one tetrahedral T site, but with a preference of Si atoms for Q⁴₁ (3Si,1Al) and Q⁴₂ (2Si,2Al) environments, in comparison with random and Loewenstein distributions, due to charge dispersion effects. However, the ²⁷Al{¹H} dipolar evolutions suggest two spectroscopically distinct T sites for Al atoms. The ²³Na and ¹³³Cs spectra indicate broad site distributions for these cavity cations. The anisotropic character of the long-range disordered pollucite structure, with a pseudo-cubic symmetry and lack of strict periodicity, can be explained from an incipient displacive transition to lower symmetry. These pollucite specimens are essentially anhydrous minerals despite the ¹H and the cross-polarization experiments suggesting that some protons exist in the structure as -OH groups, whereas water molecules were only found in relation to the phyllosilicate impurities from alteration in specimen <i>Tanco</i> and perhaps also as liquid water in fluid inclusions.