Raman spectra of TiChu with varying F content. Here, (a) low- and (b) high-frequency regions of TiChu Raman signals show identical peak positions (at 536, 602, 755, 780, 828, 845, 861, and 963). Variations of their shapes and relative heights are due to crystal orientations. While Raman spectra are useful to identify microinclusions and intergrowth of TiChu, they do not provide obvious indications of compositional variations. The order of spectra is the same for both figures.