Mica is a group of rocks and minerals that have a layered structure and are formed as a result of volcanic processes. Due to the fact that stone can exfoliate into thin layers, in the distant past it was used instead of glass.
Mica as a mineral has many varieties due to its variable chemical composition; it has a rich palette of colors and shades.
Today, mica is a valuable raw material in industry, agriculture and medicine; it is also widely used in jewelry, decoration and collecting.
Description
This mineral is widespread in nature. They have found application as a raw material for the production of rubidium and other substances, and are also used in the manufacture of glass and ceramic products. Most spars are representatives of solid solutions of the isomorphic series system (the formula for feldspar is Na[AlSi3O8] - K[AlSi3O8] - Ca[Al2Si2O8]).
Among these minerals there are many translucent and transparent, which are used as ornamental stones in jewelry. Highlight:
- andesine is a transparent or translucent variety of plagioclase, which has a color range of pink, yellowish, light green, orange-red and white;
- belomorite is a type of moonstone with light bluish reflections, in whose composition albite predominates;
- Labradorite (“Taus stone”, “peacock stone”) is a plagioclase moonstone that has a blue-black or dark blue color interspersed with the color scheme of a peacock feather;
- Bull's Eye is a brownish-purple variety of Labradorite that is tinged with red;
- spectrolite - a type of labradorite interspersed with colors throughout the spectrum;
- adularia is a moonstone that is a translucent or transparent type of potassium spar interspersed with a bluish-silver hue;
- heliolite is a translucent or transparent orthoclase in red, orange and golden yellow shades that has a schillerizing effect. It consists of the presence of a golden luster due to the content of inclusions of hematite flakes, as well as fine copper powder;
- Amazonite is a microcline in shades of bright bluish green and blue.
Feldspar stones have a hardness of 6-6.5 on the Mohs scale.
Areas of application
Industry
Various products made from electrical mica
Mica is in demand in many industrial sectors:
- Construction – ground mica is included in cement mixtures. Expanded vermiculite is the basis of thermal insulation materials.
- Chemical industry - mica is an integral component of some paint coatings, rubber and plastic products.
- Mechanical engineering - due to its electrical insulating properties, mica is used in instrument, aircraft and shipbuilding. The mineral is used as a raw material for the manufacture of electric heating devices, navigators, household appliances, as well as optical medical devices.
Agriculture
The mineral is used as a feed filler in livestock farming. In agriculture, farmers use powdered mica to mulch and fertilize the soil. Thanks to this, the soil structure improves and productivity increases several times.
Interior
Mica is used to create stained glass inserts into furniture elements, thus creating the atmosphere of past centuries. Original boxes are made from the mineral. Small crystals are used for wall cladding. Interior items made of ivory are coated with a mica composition to give the surface a pearlescent sheen.
Cosmetology
Mica is used as a raw material in the manufacture of cosmetics. It is added to creams, powders, shadows and lipsticks as pearl.
Ring with mica muscovite
Decorations
Mica is processed into a cabochon and inserted into jewelry - rings, earrings, pendants and brooches. Bracelets and beads are not made from stones, since in these products they are subject to increased mechanical stress.
Mica crystal in feldspar and quartz
Feldspar: properties
All feldspars have similar physical properties. They all have cleavage in 2 directions (lateral pinacoids and parallel to the basal one, forming almost a straight or right angle), and general hardness. Two rare minerals - strontium stronalsite and barium banalsite - are of rhombic system.
Feldspar is the main rock-forming mineral of most rock igneous rocks (in addition to pyroxenites, ultramafic and alkaline rocks), in addition to various metamorphic rocks. The composition and type of mineral determine to a large extent the name of the rock. Feldspar makes up the bulk of pegmatites. It can occur in veined hydrothermal deposits. Stones are subject to weathering (exposure to groundwater seepage and atmospheric agents), leading to their further decomposition to form various clay minerals.
Storage and care
Mica has a very low hardness index, so it requires extremely careful care. Products made from this mineral should not be dropped, nor should they be subjected to shock or compression. Immediately after removal, jewelry should be placed in a separate box and put away in a dark place.
Mica should be protected from exposure to high temperatures, as this can lead to a change in its properties. Also, do not allow the stone to come into contact with chemicals.
In case of contamination, mica products are cleaned with a soft brush using toothpaste or soap solution. After rinsing, the stone is dried naturally.
Glassy sanidine
Feldspar, such as glassy sanidine, can be found in the form of phenocrysts in rhyolites, as well as other extruded acid rocks. Often - in trachytes, in some potassic shallow intrusive alkaline rocks such as synnyrites, which received this name in honor of the Synnyr massif, located in the Northern Baikal region. The typical environment of this stone is granite, which can contain about 60% of this mineral.
Instead of orthoclase, granite often contains a potassium triclinic feldspar called microcline. Other intrusive rocks with a large proportion of orthoclase include syenite and granodiorite. The composition of feldspar, similar to intrusive acid rocks (trachyte, dacite and rhyolite), also includes orthoclase, often replaced by sanidine. In addition, orthoclase is found in migmatites, gneisses and other rocks of the highest degree of metamorphism, which were formed with the participation of granitization.
The mineral can appear in hydrothermal veins as a gangue mineral, especially at high temperatures. In addition, orthoclase can be found in arkoses (feldspathic sandstones). During its formation, sand grains accumulated so quickly that abrasion of feldspar with the formation of clay minerals did not occur.
Origin and history
Mica is a rock of metamorphic and volcanic origin. It is distinguished from other minerals and artificial analogues by its layered structure. Mica is present in many other minerals. Thus, granite is based on quartz, feldspar and mica. The pearlescent luster of precious stones also appears due to mica inclusions.
mica window
The use of this rock is traced in cave paintings from Paleolithic times. Mica layers were split into thin plates and used as window glass in Ancient Egypt, Greece and Rome, and China. In Teotihuacan, the city of Mexican gods, mica was used to decorate temples, pyramids, sculptures and statues.
In Russia, then called Muscovy, large-scale mining of muscovite was carried out. The charioteer of Peter I, the royal lamps, and window frames were made from this mineral. Mica was used in decorating icons and church regalia.
At the end of the 19th century, fluorphlogopite was created by a Russian chemist. This is an artificial analogue of phlogopite, which is superior in properties to the natural mineral, but visually has no differences. Artificial imitation can only be recognized in a laboratory setting.
Orthoclase
Monoclinic feldspar orthoclase is given its name by its cleavage at an absolutely right angle - potassium aluminosilicate. Although orthoclase is mainly found in the form of irregular grains in igneous rocks, it is capable of producing tabular crystals with one developed face strictly parallel to the lateral pinacoid. Twins are often encountered, especially of the Carlsbad type, in which there is a rotation around the twin axis with a fusion plane passing along the lateral pinacoid.
These stones are usually light in color, mostly white, sometimes pink or red (due to scattered hematite particles), and occasionally gray or yellowish. Orthoclase differs from other stones in its low density. A colorless, transparent or translucent variety of orthoclase in the form of crystals that resemble rhombohedrons is known as adularia; if it has a soft blue iridescence, it is also called moonstone.
Microcline
Microcline is a potassium triclinic feldspar with the same formula as orthoclase. In this case, sodium is able to partially replace potassium (although to a lesser extent than in orthoclase). Triclinic high-temperature alkali feldspar, which contains more sodium than potassium, is called anorthoclase. It is characteristic of some effusive, sodium-rich, less often alkaline, intrusive rocks.
Anorthoclase is very similar in physical properties, including the nature of twinning, to microcline. In addition to the Carlsbad and other simple twins that are characteristic of orthoclase, it can be polysynthetically twinned according to the albite law, while the lateral pinacoid is considered both an intergrowth plane and a twinning plane.
The intersection of these two series of strips at almost right angles produces a “lattice” effect when the microcline is observed in polarized light under a microscope. But only maximal microclines, which are characterized by a small degree of structural order, are considered lattice. The main color of the microcline is white, less often pink or red, gray, and occasionally green.
Plagioclases
The feldspar mineral also has another group - plagioclases (sodium-calcium triclinic feldspars), which form a constant series from sodium albite plagioclase to calcareous anorthite plagioclase.
Plagioclases are almost always twinned. Since this twinning is repeated many times in each sample (twins), the planes of this basal cleavage of plagioclases are covered on top with thin parallel streaks, which represent traces of contacts between twinned rocks and the emergence of twinned sutures to the surface.
The magic of mineral
Palm carved from mica
Mica of natural origin has versatile magical properties:
- promotes material wealth and career growth;
- protects against unfavorable situations (for example, frostbite in cold weather) and dangers;
- grants spiritual harmony in communication with oneself and others;
- has a beneficial effect on love relationships - it helps single people find their other half, and married couples - to return the former fire of passion in their feelings.
Some varieties of mica (for example, biotite) develop the gift of clairvoyance, sharpen intuition, and reveal previously unknown secrets of worldview.
Amazonite
Amazonite is a rock that is used as an ornamental stone. The mineral is mined in the USA, Russia (on the Kola Peninsula, the Urals and Transbaikalia), as well as in Madagascar. The potassium-sodium feldspars - microcline, orthoclase, anorthoclase, sanidine and albite - are generally called alkaline, forming one of the main groups in the spar family.
Varieties of mica
Based on the chemical composition, we can provide the following classification of the mineral in question, namely:
- Magnesian-ferruginous mica – biotite, phlogopite and lepidomelane.
- Aluminum mica – paragonite and muscovite.
- Lithium mica - zinnwaldite, lepidolite and tainiolite.
There is another typology of this mineral, which refers to the concept of “industrial mica”:
- scrap and fine mica (waste parts from the production of sheet mica);
- intumescent mica is vermiculite obtained by firing this mineral;
- leaf mica.
Grade
The price of feldspars directly depends on how rare their variety is. In addition, it is influenced by color, degree of transparency, the presence of schillerization and iridescence on the surface, as well as the place of their extraction. Thus, the price of one gram of green amazonite with a significant number of inclusions is $1-3, while samples of this stone of a dark turquoise pure tone are estimated at $10 or more per gram.
The most expensive of the feldspars is heliolite (sunstone), one bead costs $1.5, and a whole necklace costs $100.
Price
Pendant - mica, silver 925
The price of mica depends on its type, size, deposit and degree of processing complexity. The average cost for collectible samples and jewelry with this stone is:
- $35 – for a souvenir lepidolite ball with a diameter of 55 mm;
- $45 - for a similar muscovite product with a diameter of 60 mm;
- $2.8 – for a raw muscovite crystal measuring 40x20x35 mm;
- $21 – for a collection sample of lepidolite measuring 100x50x50 mm;
- $43-55 - for a silver ring or pendant with an insert of cabochon-treated muscovite.
Place of Birth
Feldspar deposits are found on all continents of our planet. The USA, Tanzania, Norway, Madagascar, and Russia can boast of heliolite deposits. In our country it is mined in Karelia and the Urals.
Adularia deposits are located in different countries of the East, including India, Sri Lanka, Tajikistan, in addition, in the USA, Switzerland, etc.
Amazonite is also mined in Ukraine, Central Asia, India, Brazil, Mongolia, Canada, etc.
Labradorite is mined in Canada, Ukraine, Egypt, Brazil, India, Norway, and Mongolia.
How to care
Feldspars need to be cared for carefully:
- Decorative items must be placed so that they do not fall and no one hits them.
- It is better to store jewelry separately from each other, in bags or wrapped in soft cloth.
- Stones should not be cleaned mechanically. Chemicals and ultrasound are unacceptable. It is enough to remove dirt with warm soapy water and dry with a soft cloth.
- Before cleaning the house, doing laundry, and going to the gym, pool, or beach, jewelry should be removed.
Amazonite is very sensitive to sunlight - it can become discolored in the sun. It will be impossible to restore the color.
Adularia and Labrador retriever periodically need to be charged under moonlight.
Feldspars: who are they suitable for?
Jewelry with lunar light stones such as adularia and belomorite will look great on bright blondes, especially those of the “summer” color type. Although they are also suitable for brunettes. Saturated amazonites, which are green in color, and orange-red heliolites will be combined with the appearance of brunettes, brown-haired women and girls who have mahogany or burgundy hair color. For girls with blond hair with a soft yellowish tint, as well as red-haired women, light green Amazonites and yellow-orange stones (spring and autumn color types) are suitable.
Astrologers advise wearing jewelry with adularia for Pisces and Cancer, and with amazonite for Aquarius, Gemini, and Libra. At the same time, there are no clear instructions about all other feldspars, therefore, all other signs can afford to wear them.
Diverse in effects and colors, feldspars today are increasingly attracting the attention of lovers of original jewelry with their interesting appearance, which makes it possible to add uniqueness to the image.
Therapeutic effect
Sample in mica apatite Russia
The properties of mica are receiving increased attention in alternative medicine. Since ancient times, supporters of Ayurveda have used mica to restore health, which became black as a result of calcination by fire. In order for the beneficial properties of the mineral to be fully revealed, the crystals had to be moved over the fire more than two hundred times.
Black mica is considered an effective remedy in the treatment of diseases of the gastrointestinal tract. It is used to alleviate conditions of joint diseases. Mica powder is recommended for drinking by people with weakened immune systems, as well as those who are in the process of an infectious disease or at the stage of recovery.
To normalize the psycho-emotional state and eliminate neurological disorders, green mica should be used. Contact with the stone will help relieve nervous tension and insomnia.
