Astonishingly gemmy crystals for the species. Crystals tend to exhibit striking pleochroism. One set of opposing faces shows a transluscent pale blue, while the other set features two distinctly zoned indigo lines encompassing a central, nearly colorless line. Crystals also typically exhibit mild red fluorescence under LW UV, due to the presence of trivalent chromium substitutions in place of aluminum.
Kadunguri Whiteschists, Zambezi Belt, Mashonaland West, Zimbabwe