What kind of rock is peridotite

Formation of rocks and minerals

A rock is a naturally occurring mixture that consists of components such as minerals, glasses or residues from former living beings. The silicates such as the minerals of the feldspar group, quartz, mica, olivine and the amphiboles make up the largest share in the structure of the rocks. Often, carbonates such as limestone or dolomite are also rock-forming. Rocks and the minerals they contain can be differentiated according to the way they were formed.
 
 

 
Basalt columns in Iceland
 
Magmatic formation
 
In volcanoes, molten rocks rise to the surface in the form of lava and gradually solidify. When the magma cools in the air, they are created Effusion rocks or the volcanic rocks. These include, for example, the basalt. Due to the rapid cooling process, only small crystals can form. The tiny crystals determine the order in the structure of the basalt, they are responsible for the typical shape of the large basalt columns when they weather. If no crystalline order is formed during the cooling process, volcanic glass is formed, to which theObsidian is counted. It often arises when viscous lava cools; it can be found, for example, on the slopes of Mount Etna in Sicily or on Vesuvius near Naples. Pumice is a foam-like volcanic glass with low density, which is criss-crossed with many cavities. It occurs when gases flow through a lava flow when it cools. Due to its density of only 0.3 grams per cubic centimeter, pumice floats on the water.
 


Igneous rocks: basalt from Iceland, obsidian from Lipari / Italy, pumice

 
The magma found in deep layers contains substances that mainly contain silicon, aluminum and iron ions, as well as ions with oxygen. During slow cooling, rock-forming minerals are formed through crystallization. The cooling of the melt in the interior of the earth takes place more slowly. There then arise under high pressure and high temperature Deep rocks or the plutonites. The granite is the most common deep rock. The components of this mixture consist of quartz, feldspar and mica. The color of the granite is mainly determined by the composition of the feldspars. These can appear reddish, yellowish, whitish or bluish. The minerals of the olivine group are also formed in the deep rock. These build the rock group of Peridotites which can contain other colored minerals. The deep rocks also include the Kimberlite, which contains mica and ilmenite in addition to olivines. This is where the valuable diamonds are created under high pressure and under certain conditions.
 


Granite and its components: quartz (with light feldspar), red feldspar and black mica
 

 
Between the effluent rocks and the deep rocks lie the Gang rocks. The minerals in it form on the way up the magma in the passage. The Granite porphyry counted, which is finer-grained compared to granite. When a melt cools on the way up, cavities are formed again and again, in which minerals and crystals can grow under particularly favorable conditions. The formation of cavities is particularly beneficial when the melt has cooled to a few hundred degrees. Then the rocks are no longer plastically deformed, but break under the action of pressure, which favors the formation of gaps and faults. Some crystal fissures in the Swiss Alps reach a diameter of more than twenty meters. When hot water, which rises from the depths and contains dissolved minerals, gets into a cavity, the minerals are precipitated and crystallize out in the process. In this way, fissures with quartz crystals several meters in size can arise. In the magmatic fissures of the Alps there are also a multitude of minerals that have formed into beautiful crystals, for example the titanium minerals rutile and titanite.

The slower, the longer and the more undisturbed the mineral-rich water circulates in a crevice, the larger and more regularly developed the crystals develop. This process can take many millions of years. The most beautiful crystals develop in the Pegmatites. These are mostly rocks rich in quartz and feldspar, which crystallize from the residual melt when the magma solidifies only at lower temperatures. It also contains precious stones and rare minerals such as tourmaline and beryl.
 
 
Sedimentary formation
 
Sedimentary rocks are caused by weathering and erosion under the influence of the sun, water, wind, temperature fluctuations and living beings. When material is deposited by streams and rivers in a delta, these deposits are later compacted and cemented to conglomerate. Clay, sand and gravel were created in this way.volume is a fine-grained rock that contains the mineral kaolinite in addition to some other components. When dry, clay is hard; when water is added, it becomes plastically deformable. It can hold water in its finest pores, so clay can hold back groundwater. It is in great demand as a building material for the manufacture of bricks and refractory stones. A clay with little lime is called Clay, a light, lime-rich tone on the other hand than marl. Through drainage and under pressure, the clay becomes the Slate. It is the typical slate used for cladding and roofing.




Sedimentary rocks: clay, marl, slate


The Sandstone is the most widespread sedimentary rock. It is created by compacting and cementing quartz grains of sand with clay or lime. The old town houses of the city of Bern, the Bundeshaus and the Bern Minster, for example, are made of olive-green sandstone. This is relatively soft and easy to work with. The mineral glauconite is responsible for the green color. Sandstone with a small amount of other minerals appears gray, while hematite colors sandstone red.

 


In the old town of Bern, many buildings are made of olive-green sandstone.
 

Mineral deposits and biological degradation processes create sediments on the sea floor. Plattenkalk forms through chemical precipitation of the water-soluble calcium hydrogen carbonate in the water. In Solnhofen, for example, fossils can be found between the plates. Solnhofer Plattenkalk is an important natural stone. Shell limestone arises from the deposition of the hard limestone shells of dead marine animals. After the sea receded, limestone mountains like the Swabian Alb emerged. During crystallization processes in water-containing cavities in the limestone mountains, the mineral calcite is formed, which can form crystal-clear crystals with a high degree of purity. If the lime in the sea water reacts with magnesium ions, dolomite is formed. The Dolomites are named after this mineral.



 
The Sella Group in the Dolomites is made up of dolomite, limestone, marl and sandstone.

 
Under special conditions, chemical sedimentation creates gypsum or salt deposits. Minerals crystallize in the cavities, which at the same time build up the sedimentary rock. Minerals such as anhydrite, gypsum or rock salt have formed in this way. The iron ore deposits were also formed in sedimentary form in the early history of the earth, when the prehistoric seas were enriched with iron salts by numerous meteorite impacts and these sedimented on the sea floor. Minerals such as celestine containing strontium can be found in sedimentary fissures or rhodochrosite in manganese ore deposits formed in sedimentation.

From the organic remnants of the fern and horsetail forests, organic sediments have formed over the course of millions of years on the bottom of the seas or bogs. At first the loose one formed peat. The carbon content accumulated under pressure and dehydration. It came into being Brown coal, later Hard coal and finally anthracite, which has the highest carbon content, the highest hardness and the best calorific value. While peat and lignite still float on the water, hard coal and anthracite go under.
 


Three stages in the transformation of former living beings: lignite, hard coal and anthracite


Metamorphic formation
 
The igneous or sedimentary rocks are pushed into the earth's crust again and again in the course of the earth's history, as is the case with the shifting of continental plates or the formation of mountains. Under the increased pressure and temperature in the deep layers, the rocks make a transformation or a metamorphosis by. It is under these special conditions that the metamorphic rocks. Lime, for example, is formed through metamorphosis marble. There are few cavities and hardly any fossils in metamorphic rocks.



Metamorphic rocks: mica schist, gneiss and amphibolite
 

Gneiss is a coarse-grained rock with a high content of feldspars. Over the course of millions of years, gneisses were created through multiple transformations from other rocks such as granite. The original rocks were transformed and reshaped by pressure, folding and shifting of the mountains and continents. If you hold a piece of gneiss in your hand, you can see parallel layers. This is what distinguishes gneiss from granite from the outside. Gneiss is very hard and is suitable for floor slabs or road construction. Mica slate consists mainly of quartz and light mica. One-sided pressure creates the leafy mica minerals with a parallel structure. It can also contain feldspar, thistle or staurolite. Amphibolite is made from basalt, peridotite or marl. The rock is rich in minerals of the amphibole or hornblende group. In the three metamorphic rocks mentioned, for example, the minerals from the garnet group occur. Serpentinite arises from igneous rocks such as peridotite. It appears greenish and slightly spotty. It is often used for wall panels and for making art objects.
   


Elements in solid form and ores for metal extraction
 
Among the naturally occurring metals in dignified shape include gold, copper, platinum, arsenic, mercury, silver or bismuth. Although the metals are in elemental form, they are often contaminated and have to be subjected to a complex cleaning process. However, not all metals occur elementarily in nature.
 
 
Gold tinsel from a river


Minerals that contain metal ions in their chemical structure or as impurities are suitable as Ores for metal extraction, provided the extraction is economically viable. From the 17th century to the 19th century, gold was extracted from gold-bearing pyrite or chalcopyrite in Gondo on the Simplon Pass. The ores were ground to a fine powder together with the gangue rock and pure mercury was added. The gold of the pyrite dissolved in the mercury and was distilled off. In this way, about two thirds of the gold present in the ore could be extracted. After the mercury treatment, the rock powder was placed in a potassium cyanide lye, the remaining third of the gold being deposited on the ground as a gold sponge. The ores are also important raw materials for the manufacture of chemical products. For example, when the pyrite is roasted, sulfur dioxide is produced, from which sulfuric acid can be produced. Potash salts, dolomite or leucite are suitable for the production of fertilizers. The ores are classified according to their main metal content:
 
 
Ore familyExamples
Lead oresLead luster, cerussite, crocoite, pyromorphite
Iron oresGoethite, hematite, limonite, magnetite, siderite
Copper oresColored copper gravel, chalcopyrite, covelline, cuprite, malachite
Manganese oresRhodochrosite, psilomelan, pyrolusite
Nickel ores
Magnetic gravel, red nickel gravel, white nickel gravel
Silver ores
Acanthite, argyrodite, chlorargyrite, prostite, pyrargyrite
Titanium oresAnatase, ilmenite, rutile
Zinc oresRed zinc candle, zinc blende, zinc spar
Rare earth
Bastnasite, euxenite, gadolinite, monazite, xenotime