Bill Minarik#Tugtupite is our second sodalite-structure (after #Haüyne). Finch et al. (2016) investigated the sources of color from point defects, bonds, and coordination in the #sodalite cage structure.
Tugupite is different, due to the beryllium substitution & also that the sodium atoms (large grey balls in the images) are five-fold coordinated, not four-fold.
Tugupite is #tenebrescent (my word of the day): it changes color in daylight, and this might be useful in window blinds.
