Color & Pigmentation:
* Titanium Dioxide (TiO2): A very common and versatile mineral used as a white pigment and opacifier. It provides excellent coverage and also acts as a sunscreen by reflecting UV rays. Different particle sizes are used for different effects. Nano-sized particles are often used in sunscreens.
* Iron Oxides (Fe2O3, Fe3O4, FeO(OH)): A group of minerals that provide a range of yellow, red, brown, and black pigments. They are used in foundations, eyeshadows, lipsticks, and other color cosmetics. Examples include Yellow Iron Oxide (CI 77492), Red Iron Oxide (CI 77491), and Black Iron Oxide (CI 77499).
* Ultramarines (Sodium Aluminum Silicate with Sulfur): Used for blue and violet pigments. Ultramarine Blue (CI 77007) is a common example.
* Chromium Oxide Green (Cr2O3): Provides a bright green pigment.
* Manganese Violet (Manganese Ammonium Pyrophosphate): Used for purple and violet hues.
* Zinc Oxide (ZnO): While primarily used for its sunscreen properties and as a skin protectant, it also contributes to opacity and a white tint.
Texture, Fillers & Absorbents:
* Talc (Hydrated Magnesium Silicate): A very soft mineral that provides a silky texture. It's used as a filler, absorbent, and to improve the spreadability of products. However, it's important to note that talc is sometimes associated with asbestos contamination, so cosmetic-grade talc must be asbestos-free.
* Mica (Various Silicate Minerals): A group of sheet silicate minerals that provide shimmer and a light-reflecting quality. Different types of mica (e.g., Muscovite, Sericite) are used to achieve various effects, from subtle glow to intense sparkle. Often coated with titanium dioxide or iron oxides for colored shimmers.
* Kaolin Clay (Hydrated Aluminum Silicate): A fine, white clay that absorbs oil and impurities, making it suitable for masks, cleansers, and powders.
* Bentonite Clay (Aluminum Phyllosilicate): Similar to kaolin, bentonite clay has excellent absorbent properties and can draw out impurities from the skin.
* Silica (Silicon Dioxide, SiO2): Used as an absorbent, bulking agent, and to improve the texture of products. It can also provide a soft-focus effect, minimizing the appearance of wrinkles.
* Magnesium Stearate: A salt derived from stearic acid, used as a filler, binder, and to improve the adhesion of powders.
* Boron Nitride (BN): Provides a silky texture, enhances adhesion, and has light-diffusing properties, helping to minimize the appearance of imperfections.
Other Functions:
* Zinc Oxide (ZnO): A broad-spectrum sunscreen that protects against UVA and UVB rays. Also has anti-inflammatory and skin-soothing properties.
* Magnesium Oxide (MgO): Used as a thickener and opacifier.
Important Considerations:
* Particle Size: The particle size of minerals like titanium dioxide and zinc oxide is crucial for their functionality, especially in sunscreen. Nanoparticles are used in some sunscreens to improve transparency and spreadability, but their safety has been debated.
* Purity: The purity of minerals used in cosmetics is essential. Contamination, particularly with asbestos in talc, is a significant concern. Reputable manufacturers use rigorous testing to ensure their minerals are safe.
* Ethical Sourcing: As with all ingredients, ethical sourcing is a growing concern for minerals used in cosmetics. Some minerals, like mica, are associated with child labor in certain regions. Consumers are increasingly looking for brands that prioritize fair labor practices and sustainable sourcing.
In summary, a wide range of minerals contribute to the functionality and aesthetic appeal of cosmetics. Understanding the properties and uses of these minerals can help you make informed choices about the products you use. Always look for reputable brands that prioritize the safety and ethical sourcing of their ingredients.