Luminescent centres in pezzottaite, CsBe₂LiAl₂Si ₆O₁₈

Pezzottaite, CsBe₂LiAl₂Si₆O₁₈, is a rare new pink mineral found in central Madagascar and Afghanistan, exhibiting a beryl-like trigonal reduced symmetry (R3c). Numerous data on its optical properties, Raman, IR, absorption spectra as well LIBS data are available, while it is described as a non-luminescent mineral under UV light. However, pezzottaite shows several laser-induced red emissions and a particular unusual blue luminescence. LIBS analysis reveals the presence of Sc, Ca, Sr, Na, K and Rb as substituted trace elements, but these elements cannot be considered as the centres responsible for the observed emissions. Timeresolved analyses under different excitations (266, 355, 514 and 532 nm) at room and liquid nitrogen temperatures allow the identification of Fe³⁺ (730 nm) and Cr³⁺ (699 nm) as red emitting centres, while Tl⁺ is considered responsible for the blue fluorescence (420-425 nm). Photoluminescence proves effective for identifying the presence of these luminescent trace elements even below the LIBS detection limit (a few ppm), but without yet attaining a quantitative resolution.