What Is The Use Of Mica In Eyeshadow

Mica is a very common rock-forming mineral, widely distributed in crystalline rocks. Its general chemical formula can be expressed as:

X { Y2-3 [Z4O10] (OH)2 }

X represents large interlayer cations, such as K+, Na+, Ca2+, Ba2+, Rb+, Cs+, etc. Y represents octahedral cations, such as Al3+, Fe2+, Mg2+, Cr3+, Ti4+, Fe3+, etc. Z is mainly Si4+ and Al3+; The ideal ratio of the additional anion (OH)- to (O)2- is 2:10, and (OH)- can be replaced by F- and Cl-. Most mica contain 4% to 5% water. Therefore, although they may be called mica, the chemical composition of different mica may be very different, for the purpose of research, we collectively refer to the minerals with this type of characteristics as mica group minerals.  

The common characteristics of mica group minerals are: layered silicate minerals, monoclinic crystal system, a few trigonal crystal system, the crystals are pseudo-hexagonal columnar, plate and sheet; The aggregate is scaly and foliaceous. It has a set of extremely complete cleavage, along which it is easy to peel into sheets. Therefore, the shape of mica is usually regarded as sheet.

A group of parallel cleavages can be seen in a photograph of biomica under orthogonal polarized (left) and single polarized (right) mirrors.

The mica variety that does not contain iron is colorless in flakes, and the higher the iron content, the darker the color, and the more polychromatic and absorbable it is. According to the different chemical composition and optical characteristics, mica group minerals can be divided into Muscovite subgroup, biotite-phlogopite subgroup and lemica subgroup. The common mica are biotite, phlogopite, Muscovite and so on.

Layer upon layer of mica

What are the uses of mica

Mica has a wide range of uses, in ancient China, it is often used to do traditional Chinese medicine, the ancients even think that taking mica: a year to remove all diseases (heavy metal poisoning), three years of long service, husband into a boy (body scrap), Zhongshan uncle Qing suit, over time can become a cloud (soul ascension). However, in the era without glass, the transparency of mica makes it a better decorative material, for example, we are familiar with the "mica screen candle shadow deep, the river gradually falling Xiaoxing sink." "Mica screen is low, tassel tent is small" and mica calf car.

Later, with the development of science and technology, people gradually realized that mica minerals have high insulation, high temperature resistance, strong acid and alkali resistance, and mica also began to enter building materials, fire, plastics, paper, rubber, pearlite pigments and other industries. These are mainly Muscovite and phlogopite.

In addition, lepidolite and ferrolepidolite can also be used as mineral raw materials for extracting lithium.

Take pearlescent pigments as an example, pearlescent pigments are a class of pigments with pearl luster, which are deposited on the substrate (generally natural mica, synthetic mica, glass sheet and other sheet-like materials) above a layer or alternately deposited multiple layers of metal oxides or non-metallic oxides and formed a flat sandwich body with a structure similar to "sandwich". Due to the difference in refractive index between the substrate and the oxide deposited on its surface and each oxide, when the light shines on the surface of the pearlescent pigment, the incident light will be refracted and reflected at the interface of each layer of the pearlescent pigment, and the color of the pearlescent pigment that people see is the result of the superposition of light after multiple refractions and reflections of the light, that is, the interference phenomenon of light.

Many of our commonly used eyeshadow and other cosmetics have added natural or synthetic mica materials to achieve the effect of blingbling, these materials are non-toxic and non-irritating, but may contain some heavy metals, but please rest assured that if you buy regular cosmetics, its composition generally meets the requirements of cosmetics heavy metal indicators, harmless to the human body!!