Douglas Harper's Etymology Dictionary
micacious
"sparkling," 1836, from Late Latin micare "to shine, sparkle, flash, glitter."
Wiktionary
micacious
a. sparkling, glittering, twinkling
Usage examples of "micacious".
The remaining rocks from here are richer in lime and iron, and show a series of gradual transitions from micacious granite, through grano-diorite to quartz diorite, with considerable quantities of dark mica, and green hornblende.