INDICUM / INDIGO
Indigo is the colour of intuition and perception. It reflects great devotion, wisdom, and justice along with fairness and impartiality. Powerful and dignified, indigo conveys integrity and deep sincerity.
Indigo is a deep midnight blue. It is a combination of deep blue and violet and holds attributes to both of those colours.
Indigo has a (disputed) wavelength of 420-450 nanometres and is not traditionally part of the basic colour-naming system. It is regarded as one of the seven colours of the rainbow; however, sources differ to its actual position in the electromagnetic spectrum.
Indigo dye is extracted from tropical plants as a fermented leaf solution and mixed with lye, pressed into cakes, and powdered.
Each cache contains a letter needed to determine the code word to receive the co-cords for the final cache in the series.