Mica refers to a group of silicate minerals that can be ground down into a fine powder for use in cosmetics. Mica is responsible for adding a shimmering effect to products such as foundation, blush, eyeliner, eyeshadow, hair and body glitter, lipgloss, mascara, nail polish, and many more.
The mica group represents 37 sheet silicate minerals that have a layered or flaky texture. In chemistry, a silicate is any member of a family of anions consisting of silicon and oxygen. Due to its natural lustrous qualities, mica likely got its name from the Latin word micare, which means “to glitter”.
In the United States, flake mica comes from Arizona, Dakota, Georgia, New Mexico, North Carolina, and South Carolina. Flake mica can be obtained from several sources: the metamorphic rock called schist as a byproduct of processing feldspar and kaolin resources, from placer deposits, and from pegmatites. Mica possesses different color properties depending on the type of rock it comes from.
Mica is used in a wide variety of cosmetic products due to its sheer, light-reflecting properties that create a natural shimmery finish. This is why mica is often referred to as “nature’s glitter”. These shimmering properties allow mica to reflect light from the face, creating the illusion of a smoother, softer, and more radiant skin tone. Since makeup can often appear very flat, adding an iridescent ingredient like mica can create depth and add contouring and highlighting to the face that looks natural.
Mica can be combined with other ingredients to create different types of effects. For instance, by covering flecks of mica in titanium dioxide, the pearlescent powder can reflect all the colors of the rainbow. Combining mica with iron dioxide can help create earthier and more golden hues. Barium chloride and sodium sulfate can help reduce some of the extra glossy look.
Another way to create various types of makeup products with mica is to alter the particle size. According to FutureDerm, using different particle sizes allows makeup manufacturers to offer consumers a variety of looks, from a silky satin sheen to something that appears more glittering. Size can also affect the color; at various nanometers mica can emit light in shades of red, blue, green, etc.
In addition to helping face and eye makeup look more aesthetically pleasing, you’ll also find mica in cosmetics such as nail polishes and lip glosses due to its iridescent, shimmering properties. Additionally, some brands of toothpaste include powdered white mica. This acts as a mild abrasive to aid polishing of the tooth surface, and also adds a cosmetically pleasing shimmer to the paste.
Since mica is derived from a natural source, it is a particularly well-loved ingredient among organic and natural beauty brands.
The Food and Drug Administration (FDA) lists mica as a color additive exempt from certification. Mica is safe for use in coloring products, including cosmetics and personal care products applied to the lips, and the area of the eye. The Cosmetic Ingredient Review (CIR) Expert Panel has deferred evaluation of mica because the safety has been assessed by FDA.
According to Cosmetics Info, since mica comes from the earth, it may contain trace amounts of heavy metals. The levels of heavy metals in mica are regulated by the FDA, and the small amounts that may eventually be in cosmetic or personal care products do not pose a risk to human health.
Mica can be dangerous if it is inhaled because the particles can get into the lungs and cause scarring. Thus, any powder or aerosol products containing mica are the most concerning. There are some case reports that found mica can cause pneumoconiosis, which causes lung and breathing problems as it progresses. However, safety concerns generally focus on those who are working around mica in an industrial setting.
References: Wikipedia, “Mica”, Wikipedia, “Silicate”, Vogue, “Skincare Alphabet: What is Mica?”, FutureDerm, “What Does Mica Do in Makeup?”, 2012, Truth In Aging, “Mica”, Cosmetics Info, “Mica”, Occup Environ Med. “Mica pneumoconiosis” 1983;40:22-27.