The mica group of sheet silicate minerals includes several closely related materials having nearly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition.
When handling mica, you should wear a dust mask as when working with any other quartz / limestone / marble powder.
The Mica print recipe used mica powder of 100 micron particle size or smaller; ideally < 50 micron would be used.
Image credit: Pascal Terjan from London, United Kingdom / CC BY-SA
Mica is an abundant silicate mineral, often used for drywall, paint filler, roofing, and insulation.