Yellow Mn-rich fluor-elbaite from Canary Mine, Zambia, was heat-treated at temperatures up to 900C at ambient pressure, and the structural polyhedral distortion effects were studied using various analytical methods, including Electron Probe Micro-Analyses (EPMA), Single-crystal structure refinement (SC-SREF), Raman and Optical Absorption Spectroscopy (OAS).All the samples are enriched in Mn with content ranging between 0.72 and 0.85 apfu (atoms per formula unit), and can be classified as fluor-elbaite with Li of 0.84
Bačík et al. (Wed,) studied this question.