Mica

Описание

Cosmetic mica, potassium aluminum silicate dehydrate, is refined and ground to particles of ≤150 μm. This material imparts a natural translucence when used up to 20% in formulations of face powder blushes. Mica is available as wet ground (creamy) or as dry ground (matte).

Химические свойства

Mica (muscovite), takes the form of a colorless, odorless solid that separates into flakes or thin sheets of hydrous silicates.

Вхождение

Mica exists in nature in a wide variety of compositions. Muscovite and phlogopite are the only natural micas of commercial importance. Vermiculite, although not considered a true mica by most mineralogists, is a micaceous mineral formed from the weathering of phlogopite or biotite and is also of commercial importance.

Использование

mica is used as a texturizer and coloring agent in cosmetics, it provides a “glimmer” or “shimmering” quality in makeup powders. Mica is the group name for a series of ground silicate minerals with similar physical properties but varied chemical composition. Micas range in color from colorless to pale green, brown, or black.

Определение

Any of several silicates of vary-ing chemical composition but with similar physicalproperties and crystalline structure. All character-istically cleave into thin sheets that are flexible andelastic. Synthetic mica is available. It has electri-cal and mechanical properties superior to those ofnatural mica; it is also water free.

Методы производства

Mica is a nonfibrous, natural silicate, found in plate form in nine different species. These materials are hydrous silicates, and the predominant minerals of commerce are muscovite, a hydrous aluminosilicate, and phlogophite, a magnesium silicate. Sheet forms of mica in the form of muscovite have historically been mined by hand from pegmatites.

Общее описание

MICA, a generic term, refers to any of a group of approximately 30 silicate minerals occurring as non-fibrous plates. Muscovite (hydrated aluminium potassium silicate[KAl2(AlSi3O10)(F, OH)2 ])and phlogopite (potassium magnesium aluminum silicate hydroxide) are the two major micas of commerce. Micas are commonly found in ordinary rocks. Inhalation of mica dust presents an occupational hazard.

Профиль реактивности

MICAS have generally low chemical reactivity.

Опасность

(Dust) Irritant by inhalation, may be dam-aging to lungs. Pneumoconiosis.

Угроза здоровью

Mica dust causes pneumoconiosis.

Сельскохозяйственное использование

Biotite is a widely distributed and important rockforming mineral of the mica group. The general term designates all ferro-magnesium micas, also called black mica or magnesium-iron mica. This black and plate-like mineral is found in some igneous rocks, such as granite. It is tetrahedral mica with aluminum substituted for silicon in the tetrahedral sheet, and ferrous (Fe²⁺) or magnesium (Mg²⁺)io ns in the octahedral sheet.
Potassium release occurs more easily with biotite than with muscovite. Biotite is used as the source of soil potassium. It is more easily weathered to chlorite than muscovite and, therefore, is less common in sediments. Although commercially unimportant under hydrothermal conditions, biotite transforms to vermiculite which expands on heating and has widespread application as light-weight concrete, plaster aggregate, insulation, plant growing medium and lubricant.

Промышленное использование

Commercial mica is of two main types: sheet,and scrap or flake. Sheet muscovite is used asa dielectric in capacitors and vacuum tubes inelectronic equipment. Lower-quality muscoviteis used as an insulator in home electrical productssuch as hot plates, toasters, and irons.
Scrap and flake mica is ground for use in coatingson roofing materials and waterproof fabrics,and in paint, wallpaper, joint cement, plastics,cosmetics, well-drilling products, and avariety of agricultural products.For many years, glass-bonded mica hasbeen used in every type of electrical and electronicsystem where the insulation requirementsare preferably low-dissipation factor at high frequencies,a high-insulation resistance anddielectric-breakdown strength, along withextreme dimensional stability. Glass-bondedmicas are made in both machinable grades andprecision-moldable grades. Basically, the materialconsists of natural mica flake bonded witha low-loss electrical glass.
The availability of synthetic mica resultedin the development of so-called ceramoplastics,consisting of high-temperature electricalglass filled with synthetic mica. Ceramoplasticsprovide an increase in the electrical characteristicsover those of natural mica, and, inaddition, are more easily molded and havegreater thermal stability.

Профиль безопасности

The dust is injurious to lungs.

Возможный контакт

Mica is used as reinforcing filler for plastics, substitute for asbestos; for insulation in electrical equipment; used in the manufacture of roofing shingles, wallpaper and paint.

Несовместимости

Silicates react with lithium.

Утилизация отходов

Consider recycling, otherwise, this chemical must be disposed of in compliance with existing federal and local regulations. Landfill.