Metamorphic rocks may contain fossils

Metamorphic rocks (metamorphic rocks)


Overview:

- Metamorphic rocks (metamorphic rocks)
marble
Dolomite marble
Silicate marble
Amphibolite
Mica slate
Quartzite slate
Quartz mica slate
Quartzite
Serpentinite
Gneiss
Migmatite
Phyllite
Eclogite
Granulite / pyroxene granulite
Talc slate / soapstone
Fruit slate
Chiastolite slate / andalusite slate
Chlorite shale
Hornfels



Metamorphic rocks (metamorphic rocks)

Metamorphic rocks usually look slate, paneled or banded, depending on how they were formed. Their grain sizes vary from very fine to coarse-grained. Depending on the degree of metamorphosis, they can also look similar to the parent rocks.
The mineral inventory of a metamorphic rock describes the stage of transformation of sedimentary, igneous or metamorphic parent rocks reached by metamorphosis. Only the main components (mineral content of more than 10% of the volume) are decisive for the rock naming.

Metamorphosis (formation process of metamorphic rocks) is understood as the mineralogical change of rocks (igneous rocks and sedimentary rocks) while maintaining the solid state as a result of physical and chemical conditions that have prevailed outside the range of weathering and diagenesis in the earth's crust and that now differ from differentiate between the prevailing conditions during the formation of the parent rock.

Metamorphites arise through recrystallization or recrystallization of existing ones Igneous rocks (Igneous rocks) or Sedimentary rocks (Sedimentite) and are dependent on the physical parameters pressure (depth) and temperature. A distinction is made between two different types of metamorphosis.
The metamorphic rocks marble , Dolomite marble , Silicate marble , Amphibolite , Mica slate , Quartz mica slate , Quartzite slate , Quartzite , Serpentinite , Gneiss , Migmatite , Phyllite , Eclogite , Granulite / pyroxene granulite , Talc slate / soapstone , Fruit slate , Chiastolite schist, Chlorite shale u. Hornfels can either be described according to their microstructure, their mineral composition (phenotypes), or their parent rock (educt) (genotype).

In the case of igneous parent rocks, a metamorphosis usually only leads to a change in the structure via the directed pressure. The mineral composition of the rock is mostly preserved.
The course of the metamorphosis is different from that of the igneous rocks with sedimentary rocks, which normally formed at the temperature prevailing on the earth's surface. So be very pure Quartz sandstone or limestone the sedimented minerals are unstable at high pressure and / or temperature. As a result, the minerals of the rock are partly replaced by newly formed mineral types that only occur in metamorphic rocks by means of the sedimentation-related new distribution of the chemical components within the sediments.

1.Thermal metamorphosis (contact metamorphosis)
Contact metamorphosis occurs when the temperature is heated with a constant, low pressure effect. Contact metamorphosis means the granular recrystallization and recrystallization of the parent rock (recrystallization, crystal loblastesis). Any existing porosity will disappear because the individual grains come into direct contact with one another.
Contact zones (contact aureoles) develop around the granite plutons, the structure of which in the interior is mostly uninterrupted and randomly fine-grained (Hornfels). Characteristically, porphyroblasts appear on the outside (chiastolite schist). Porphyroblasts are spots, sheaves and knots like sprouts of new minerals.

2. Regional metmorphosis
In the so-called regional metamorphosis, a further distinction is made between thermodynamo metamorphosis and immersion metamorphosis.
- Thermodynamo metamorphosis
In addition to the acting temperature, a directed pressure leads to the regulation of newly formed crystals (e.g. mica minerals) in a surface. This creates a new surface structure in the rock.
Thermodynamo metamorphosis is related to large-scale (regional) movements through the upper crust of the earth. Rocks formed by thermodynamo metamorphosis with a corresponding parallel texture are Gneisses and Mica slate .
- Submergence metamorphosis
One speaks of sinking metamorphosis when rocks (magmatites and sedimentites) are shifted over time to greater depths of the earth's crust in such a way that the load pressure acting on all sides rises sharply and the temperature rises less sharply. Because there are no orogenic (deforming) movements, the corresponding metamorphic rock is not shale and the original structure is largely preserved. Only the mineral inventory changes.

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marble is a medium to coarse-grained metacarbonate rock, which consists of at least 80% calcite. Other aggregates of marble are mica such as muscovite, phengite and phlogopite as well as graphite. Pyrite and organic carbon compounds (bitumina) occur rarely. With light marble types there is a risk of discoloration due to capillarity and possible accessory minerals such as pyrite. The color palette of the different types of marble ranges from black-striped to yellow, green, pink, brownish, gray and white, the world-famous marble from Carrara.
Marble is created by transforming limestone . Under the influence of high pressure and high temperatures as a result of Regional metamorphosis or Contact metamorphosis of limestone, in connection with rising magma bodies from the earth's mantle (calcite marble). If dolomitic basic masses were converted, one speaks of Dolomite marble .
During the conversion through contact metamorphism, granitic magmas intrude into the earth's crust. However, these magma chambers do not reach the surface of the earth, but remain within the earth's crust. There they cool down for millennia granite or other igneous rocks similar compositions. During this period, neighboring calcareous rocks around the granite pluton can transform to marble.
In the so-called regional metamorphosis, the large amounts of rock are transformed under pressure and heat without contact with magma. These processes are very slow. It can, for. B. Gap-shaped marbles arise. The direction of the gap is usually orthogonal to the direction of printing.

The small pore space within the structure of calcite marble leads to a relatively high frost resistance. However, they are often not frost-resistant, so that the frost resistance of the respective type of rock must always be checked.
Untreated calcite marble is not recommended for use in the kitchen area due to its high sensitivity to acids (vinegar, wine, citrus fruits and cleaning agents). Acids can cause staining. Also, due to the composition (silanes, siloxanes), stain protection treatments are not advisable.
Dolomite marble is much less sensitive to amidosulfonic or fruit acids than calcite marble.

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Dolomite marble are white, gray or brownish rocks that were created from pure dolomite stones. Frequent secondary parts are the mica phlogopite and pyrite.
Dolomite marble is from marble difficult to distinguish. In comparison to marble, the technically somewhat higher quality dolomite marble is to be treated, laid and cared for just like all types of marble.
Use: floor coverings, solid work, sculptural stone, wall and facade cladding.

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Silicate marble / calcium silicate stones are metamorphic rocks that are formed in very different structures. Their structure can be directionless to streaky-fibrous and dense to grainy-crystalline and have white, grayish, yellowish and greenish colors. In addition to calcite, there are also silicate minerals such as mica (fuchsite, phlogopite), garnet (e.g. grossular), clinopyroxene, quartz, tremolite, Vesuvian or wollastonite. Dolomite is also rarely found. Silicate marbles are characterized by spacious Regional metamorphosis emerged from clayey or sandy limestones. However, the silicate content in the rock can also be caused by magmatic influences ( Contact metamorphosis ) have been supplied.
Use: work in interior design

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Amphibolite is a gray to dark green, black green rock with a medium to coarse-grained, partly massive, partly slate structure. Amphibolite consists of the main mixture parts amphibole (30-70%), plagioclase (15-40%), quartz, garnet. Pyrite also occurs rarely from.
Use: Mainly for floor coverings, wall and facade cladding

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Mica slate is a medium to coarse-grained rock and has a planar and linear structure. The mineral grains are macroscopically recognizable.
Mica schist is a generic term for schisty metamorphic rocks and are made from metamorphic rock Gneiss distinguished by the lower proportion of feldspar. The proportion of feldspar is less than 20%. The proportion of phyllosilicates (mainly muscovite) is more than 50%. In addition to quartz, other batches include garnet, staurolite and thistle.
Use: floor coverings.

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Quartz mica slate is a schisty, evenly splitting metamorphic rock. Its color palette ranges from light to dark gray.
It consists of the main components quartz, feldspar, muscovite and biotite. The proportion of mica is always lower than the proportion of quartz (<80%). The proportion of feldspar is less than 20%. Other mixed parts of quartz mica slate are hornblende and garnet.
Quartz mica slate goes in when the quartz content increases Quartzite slate and with a further increase in the quartz content in Quartzite above.
In order to achieve better adhesion of rough slabs in the mortar bed, an adhesive bridge should be used when laying.
Use: floor coverings.

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Quartzite slate (also mica quartzite or sericite quartzite) occur in the colors white, light gray, greenish and reddish brown. It differs from the massive, banky quartzite in its cleavage and its higher proportion of quartz (between 80 and 90%). Other parts of the mixture are muscovite and thistle. Muscovite causes the foliation and thus the fissibility of the quartzite slate, Quartz mica slate u. Quartzite .
In order to achieve better adhesion of rough slabs in the mortar bed, an adhesive bridge should be used when laying.

Use: Floor coverings, solid work, paving stones, wall and facade cladding.

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Quartzites are fine to medium-grain rocks. The massive, banky-looking metamorphic rocks emerged from Quartz sandstone and have a quartz content of at least 90% as the main part of the batch. Secondary constituents are silicate minerals such as muscovite, thistle (cyanite), epidote and dumortierite. Hematite, magnetite and pyrite often appear as coloring minerals and color the otherwise white-gray quartzite gray, greenish, brownish-reddish or bluish.

Since quartzite consists almost exclusively of interconnected, recrystallized quartz grains, it is a very hard, brittle rock that is resistant to erosion and weathering and very mechanically resilient. As a result of the recrystallization, the quartz grains grow beyond their original grain boundaries and thus form a densely networked structure. Structures contained in the sandstone such as fossils are mostly destroyed by this process, but in rare cases they can be retained in outline.

Cement quartzites are to be distinguished from quartzites formed by metamorphosis (meta-quartzites). Cement quartzites are intensely cemented by pebbly (quartzitic) binders Sandstones .

The physically and chemically very resistant quartzite can easily be distinguished from the optically very similar types of marble by scratching the surface. Due to its weakening in the structure (so-called stitches) caused by its formation, quartzite should not be used as a floor covering on underfloor heating.
Use: floor coverings, solid work, paving stones, wall and facade cladding.

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Serpentinite is a metamorphic rock that consists of granite originated. They are black-blue, greenish, brownish and red-brown in color and are mostly made of serpentine. Serpentinites are massive, sometimes slate-shaped, dense metabasites from the serpentine minerals lizardite, antigorite and chrysotile. Often minerals from the previous peridotite stage such as olivine, bronzite, pyrope-rich garnet or diopside-rich pyroxene appear. The occasional red coloration of serpentinite is caused by the hematite that gives it its color. Serpentinite is produced by hydration of olivine, pyroxene and hornblende in the so-called serpentinization.
Serpentinites are not acid-resistant and sensitive to the effects of weathering, technically comparable to marble. Therefore, it is not advisable to use it outdoors. When laid in hydraulically setting cementitious adhesive systems, serpentinites tend to bowl due to hydration. Suitable adhesives should therefore be used when laying serpentinites. Alternatively, the material can be watered before laying and then covered afterwards.
Use: indoor flooring and wall coverings.

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Gneiss are in Orthogneiss (magmatic origin) u. Paragneiss (sedimentary origin) divided.

- Orthogneiss originated from granites and therefore look very similar to you in terms of their grain sizes and colors. However, they differ optically by their clearly pronounced banding.

- Brazil trip originated from sedimentary rocks, but are technically very similar to granites. They are easy to distinguish from other rock groups by their unmistakable layering and stratification character as well as by their dominant white and gray to dark gray colors.

Gneisses have a high degree of conversion and are medium to coarse-grained metamorphic rocks with a pronounced parallel structure (layered texture). They appear in the colors gray, green-gray, red-gray and red-brown.
The main parts of the mix are like the granite Quartz, feldspar (mostly orthoclase) and light and dark mica (biotite, muscovite, fuchsite). The proportion of feldspar is usually more than 20%. Secondary batch parts can include cordierite, sillimanite, staurolite, thistle, garnet, epidote and hornblende. Their mineral content and their secondary mixture parts can give an indication of the genesis.
With gray, biotite-rich paragneiss there is a high risk of discoloration.
Use: floor coverings, wall coverings, paving stones.

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Migmatite (anatexite) are macroscopically very heterogeneous rocks (so-called mixed gneisses), which occur in red, red-brown, red-gray, gray and greenish colors. Some of them have a metamorphic as well as an igneous-looking structure.
Migmatite / anatexite is a rock that has partially melted as a result of an increase in temperature, decrease in pressure and / or supply of fluid (Anatexis). The anatexis is mostly laid out on a large regional scale. With an (almost) holistic melting of the migmatites (Diatexis), the dark (mafic) mineral components of a rock are also melted.
The light parts in the migmatites are of a granite-like composition (quartz and feldspar). They are called leucosomes. Leukosomes almost always represent partial The altered metamorphic rock from which the leukosome emerged is called residual rock (restite).
The dark (mafic) minerals such as biotite, hornblende, cordierite, garnet and aluminum-rich minerals such as sillimanite remain in the residual rock. The remaining rock is called a melanosome.
Due to the changing arrangement of leukosomes and melanosomes, the migmatites often have very conspicuous structures. In the migmatite, the leukosome can be vein-shaped, layered or diffusely distributed between the breccia-shaped dismembered melanosome. On the other hand, the melanosome is often streaky in the leukosome. However, misty (nebulitic) homogenizations of both minerals also occur. Often, earlier fold textures are depicted as flowing folds in the rock.
Use: Floor coverings, solid work, paving stones, wall and facade cladding.

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Phyllite have a fine grain and appear in dark gray to gray-black and greenish-gray to violet-gray colors.
The finely crystalline, thin slate, mostly leafy phyllite has a sericite content of at least 50%. Sericity creates the silky sheen on the foliage surfaces. Quartz is another main part of the batch. In addition to mica, feldspar, clorite, biotite, augite, tourmaline and iron oxide can also occur as secondary components.

- Serizite phyllite / sericite slate, is a variety of phyllite alongside quartz phylite. It consists predominantly of sericite and quartz without any significant side effects.

- In addition to sericite phyllite, quartz phyllite is a variety of phyllite. Quartz predominates as one of the main parts of the mixture compared to mica or other leafy minerals.
Use: floor coverings

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Eclogite is a massive, fine to coarse-grained rock and has a granoblastic (even) mosaic structure. Eclogite occurs in reddish and greenish colors. They arise at higher degrees Regional metamorphosis.
Eclogites with basaltic chemistry consist of the main coloring parts, omphacite and garnet. The proportion of pyrope-rich garnet (red coloring) is 50 - 90% and of pyroxene omphacite (green coloring) 5 - 50%. Quartz, disthene, rutile, titanite, pyrite and silicates such as amphibole, disthene, muscovite and zoisite are often included as secondary components.
Eclogites with granitic chemistry often contain the aluminum-rich light mica phengite.
No plagioclase (feldspar) occurs in all eclogites, since feldspar is broken down when the pressure increases (albite = jadeite + quartz). At extremely high pressure, the so-called ultra-high pressure metamorphosis, coesite, the high pressure modification of quartz and diamond, can also be contained.

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Granulite / pyroxene granulite have a white to white-gray, gray-greenish color. They are optically as well as technically granite-like stone that is made from Paragneiss and Mica schists originated.
The mostly massive rock has a medium to coarse grain size and has a granoblastic (even) mosaic structure. Occasionally, by adjusting quartz, biotite and / or the appearance of leuco and melanosomes (Anatexis) one, the Gneiss similar structures arise. The main components of granulite are feldspar (alkali feldspars and plagioclase), quartz and garnet (almandine). Granulites do not contain muscovite.
A dark variety is pyroxene granulite with a pyroxene content of up to 50%.
Due to the capillarity and the mineral content, there is a high risk of discoloration in the case of granulites due to the addition of water. This is why this stone, similar to marble, should only be laid with quick-setting laying systems and using sealing slurry on the underside of the material. Granulite must be impregnated in any case.
Use: floor coverings, wall and facade cladding.

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Talc slate / soapstone is a magnesium silicate and occurs in green, gray, yellowish and silver-white colors. Talc shale is mined almost all over the world and is therefore composed very differently depending on its origin. Therefore, these stones differ in their hardness and fragility according to their regional origin.
In addition to the very soft, greasy mineral talc (magnesium hydrosilicate), the main components are generally the minerals chlorite, magnesite and serpentine. The hydrous magnesium hydrosilicate is a metamorphic-metasomatic conversion product from magnesium-rich minerals such as olivine, pyroxene or amphibole.
Massive, dense talc is also known as soapstone or soapstone. Soapstone is very soft. It is therefore very easy to process mechanically and is not acid-soluble.
Use: sculptures.

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Fruit slate arises from heating as a result of the action of mostly granitic magmas on clay rock. This leads to Contact metamorphosis , i.e. to convert the clay minerals into mica and andalusite (anhydrous aluminum silicate).
Fruit slates generally consist of a fine-grained mixture of sericite, chlorite and biotite. Depending on the degree of metamorphosis, chlorite, biotite, cordierite and andalusite (anhydrous aluminum silicate) occur as insects (porphyroblasts) and appear in the colors gray and green-gray.
Fruit slate is a low-metamorphic rock that is formed at low pressures and temperatures of approx. 400 ° C. In the process, around the deep rock formations of contact rocks, starting from the magma body, as fruit slate, sheaf slate, nodular slate, Hornfels , over andalusite-free serite slate to unchanged Mudstone vary.
Use: floor coverings, wall and facade cladding.

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Chiastolite slate / andalusite slate arise through Contact metamorphosis and have a porphyroblastic (non-uniform grain) microstructure. While the clay minerals are fine-grained, the andalusites are medium to coarse-grained. The shape of the clay minerals can hardly be recognized, those of the andalusites are idiomorphic. The texture of the chiastolite slate shows a slate spatial arrangement and its space filling is complete.
If the feldspar content is less than 20%, it is referred to as a slate, if the content is over 20%, then it is one Gneiss .

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Chlorite shale like talc slate belongs to the group of green slates. It arises through Regional metamorphosis and are greenish in color.
Besides the green-colored mineral chlorite, feldspar also occurs as the main mix.
Chlorite slates have a fine-grain structure. The absolute size is determined by the fine-grained feldspar, while the chlorite is in the very fine-grained area. The shape of the batch parts cannot be seen.
Their texture shows a well-developed foliation with uninterrupted space filling.
If the feldspar content is less than 20%, it is referred to as a slate, if the content is over 20%, then it is one Gneiss .
Use as a decorative stone for floor slabs, wall and facade cladding.

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Hornfels is a generic term for, through Contact metamorphosis modified original rock (modified slate with garnet, magnetite, cordierite, andalusite, biotite or sillimanite). Horn rocks are usually hard and have a fine to medium-grained, massive structure with an often horn-like sheen on fresh, shell-like fracture surfaces.
They occur according to their parent rock and their admixtures, mostly in greenish-gray, greenish, bluish, black, rarely in white colors, but mostly speckled.
The name Hornfels is only used for rocks caused by contact metamorphosis. In the case of regional metamorphic formation, only the term rock is used.
Varieties of the Hornfels include the Garnet Hornfels, Chiastolite Hornfels, Pyroxen Hornfels and Cordierite Hornfels.
Use: floor coverings, wall and facade cladding.

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