Lamellar Mica Muscovite (1) Raw Minerals Stones Rocks Collecting

Description

Origin : Madagascar

Lamellar Mica Muscovite 10-20 gr - cm 4-10 Raw Minerals Stones Rocks for Collection.
Phyllosilicate Potassium and Aluminum, lamellar crystal habit.
Also available in lots, at this link, or the Mica Lepidolite (granular, lamellar or mammillary form).

Micas are a group of minerals belonging to the subclass of phyllosilicates. Micas are characterized by a layered structure and perfect flaking. These minerals generally crystallize in the monoclinic crystal system, with a tendency to form tabular crystals with lozenge or hexagonal cross-sections and assume pseudo-orthombic or pseudo-hexagonal morphologies.
Structurally micas can be classified as di-octahedral and tri-octahedral. Di-octahedral micas include common micas and Muscovite, while tri-octahedral micas include Biotite and Lepidolite. Both di-octahedral and tri-octahedral micas if fine-grained can be called clayey micas. Micas commonly contain 4-5% by weight of H2O, but are neither fat soluble nor water soluble.
All micas have the same spatial organization of the atoms, this means that their characteristics (such as perfect cleavage) are common to the whole group.
It is hypothesized that the term "mica" derives from the Latin micare or "to shine", in reference to the brilliant appearance of these minerals or from mica, "briciola", since they crumble easily.
Particularly widespread micas in nature are Muscovite and Biotite which participate in the constitution, for example, of granite. In Italy we find deposits in Veneto, Tuscany, Elba, Lombardy and Piedmont. India, Canada and the USA are the countries of greatest production of micas.
Micas are excellent thermal and electrical insulators. An example is Muscovite, as it has many uses in industry as an insulator, although currently it tends to be replaced by synthetic materials.
Generally, micas made up of large and transparent sheets have industrial applications; on the other hand, those in thinner leaves are used for lampshades, stove doors, protective glasses, lamp tubes and for various electrical instruments, given the resistance of this mineral to heat. Furthermore, pressed mica plates are used in the construction of greenhouses, instead of glass.
Micas are mainly used in decorative cosmetics. These minerals can be mixed together to obtain a large variety of colours, with the aim of decorating cards and trinkets.
Some manufacturers of toothpastes use white mica powder, exploiting its slight abrasive effect to clean the surface of the teeth.

Muscovite is a silicate belonging to the mica group. The perfect cleavage of this mineral makes it possible to obtain very thin, transparent and flexible sheets, it has a pearly glassy sheen, even if it is usually found in isomorphic mixtures with other micas (black biotite due to the presence of iron). The name originates from the city of Moscow where this mineral was used in large quantities instead of glass, there were even houses that had windows made with muscovite.
Muscovite is a very common mineral in intrusive igneous rocks high in silica (acid) such as granites, syenites and pegmatites and in metamorphic rocks.
Muscovite is also known as white mica or common mica and is widely used as an insulating material in electrical apparatus and especially vacuum tubes.
Large deposits of muscovite are found in Russia, Brazil, USA, India, Pakistan. In nature it occurs in a solid state.
The green variety is also known as fuchsite (for sale on this site). It is a chromiferous muscovite, even if it has been used little as a material to extract chromium because it is not very profitable to exploit. Chromium is responsible for its green color. If you look closely you can see lines and if you look against the light and perpendicular to these lines you can see its characteristic sheen between oily and mother-of-pearl.
Astrolite is a variety of muscovite that occurs as spherical aggregates of tabular crystals originally considered a species in its own right.