That luminous glow catching the light in your favorite eyeshadow? It’s mica, a naturally occurring silicate mineral that’s been the beauty industry’s secret to shimmer for decades. When manufacturers coat thin sheets of mica with metal oxides (most commonly titanium dioxide), they create the pearlescent pigments responsible for everything from your holographic highlighter to the sparkle in your nail polish. The science is surprisingly simple: different oxide coating thicknesses produce different colors, transforming a humble mineral into a $1.2 billion cosmetic ingredient market as of 2025, projected to nearly double by …