Mica

Description

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).

Chemical properties

Soft, translucent solid; colorless to slightred (ruby), brown to greenish yellow (amber). Noncombustible.Heat resistant to 600C.

Chemical properties

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

Occurrence

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.

The Uses of Mica

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.

The Uses of Mica

Electrical equipment, vacuum tubes, incan-descent lamps, dusting agent, lubricant, windowsin high-temperature equipment, filler in exteriorpaints, cosmetics, glass and ceramic flux, roofing,rubber, mold-release agent, specialty paper for insu-lation and filtration, wallpaper and wallboard jointcement, oil-well drilling muds.

The Uses of Mica

Mica is a generic term that applies to a wide range of hydrous aluminum silicate minerals characterized by sheet or plant-like structure, and possessing to varying degrees, depending on composition and weathering, flexibility, elasticity, hardness, and the ability to be split into thin (1 μm) sheets.

Definition

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.

Definition

A member of an important group of aluminosilicate minerals that have a characteristic layered structure. The three main types are biotite, lepidolite, and muscovite, which differ in their content of other elements (such as potassium, magnesium, and iron). Mica flakes are used as electrical insulators, dielectrics, and small heat-proof windows.

Definition

mica: Any of a group of silicate mineralswith a layered structure. Micasare composed of linked SiO₄ tetrahedrawith cations and hydroxyl groupingsbetween the layers. The generalformula is X₂Y_4-6Z₈O₂₀(OH,F)₄, whereX = K,Na,Ca; Y = Al,Mg,Fe,Li; and Z = Si,Al. The three main mica mineralsare:
muscovite, K₂Al₄(Si₆Al₂O₂₀)(OH,F)₄;biotite, K₂(Mg,Fe²⁺)_6-4(Fe³⁺,Al,Ti)_0-2^-(Si_6-5Al_2-3O₂₀)(OH,F)₄;
lepidolite, K₂(Li,Al)_5-6(Si_6-7Al_2-1O₂₀)^-(OH,F)₄.
Micas have perfect basal cleavage andthe thin cleavage flakes are flexibleand elastic. Flakes of mica are used aselectrical insulators and as the dielectricin capacitors.

Production Methods

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.

General Description

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.

Reactivity Profile

MICAS have generally low chemical reactivity.

Hazard

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

Health Hazard

Mica dust causes pneumoconiosis.

Agricultural Uses

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.

Industrial uses

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.

Safety Profile

The dust is injurious to lungs.

Potential Exposure

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.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately. If a personbreathes in large amounts of this chemical, move theexposed person to fresh air at once

storage

Color Code—Green: General storage may be used.Prior to working with this chemical you should be trainedon its proper handling and storage. Store in tightly closedcontainers in a cool, well-ventilated area

Incompatibilities

Silicates react with lithium.

Waste Disposal

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