21 CFR § 73.1496 - Mica.
(1) The color additive mica is a white powder obtained from the naturally occurring mineral, muscovite mica, consisting predominantly of a potassium aluminum silicate, K2Al4(Al2Si6O20)(OH)4 or, alternatively, H2KAl3 (SiO4)3. Mica may be identified and semiquantitatively determined by its characteristic X-ray diffraction pattern and by its optical properties.
(2) Color additive mixtures for drug use made with mica may contain only those diluents listed in this subpart as safe and suitable for use in color additive mixtures for coloring drugs.
(b) Specifications. Mica shall conform to the following specifications and shall be free from impurities other than those named to the extent that such other impurities may be avoided by good manufacturing practice:
(c) Uses and restrictions. Mica may be safely used in amounts consistent with good manufacturing practice to color dentifrices and externally applied drugs, including those for use in the area of the eye.
(d) Labeling requirements. The label of the color additive and of any mixture prepared therefrom intended solely or in part for coloring purposes shall conform to the requirements of § 70.25 of this chapter.
(e) Exemption from certification. Certification of this color additive is not necessary for the protection of the public health, and therefore batches therof are exempt from the certification requirements of section 721(c) of the act.