A rock It is a hard stone, of great solidity, which is composed of one or several minerals. Metamorphic , meanwhile, is what was subjected to a process of metamorphism .
We can say, therefore, that Metamorphic rocks they are rocks created from metamorphism. To understand the scope of the notion, we must know what this is process .
Metamorphism implies the transformation of the composition of a material, without a change in state . The process occurs when the material in question faces pressure or temperature conditions different from those that allowed its development . Metamorphism can also be triggered by the injection of a fluid.
A rock, when these conditions change, loses its thermodynamic equilibrium . In this way, you will seek to take advantage of the Energy to make an evolution that allows you to regain balance in the new conditions. The rock resulting from this process will receive the qualification of metamorphic rock.
There are processes similar to metamorphism, although with certain different characteristics, which give rise to other types of rocks. The sedimentary rocks are those that arise after a process of diagenesis while the magmatic rocks they form through fusion with magma . The mixed rocks Finally, they are the result of a partial merger with metamorphic sectors.
When the rock is at temperatures and pressures higher than the original ones, the metamorphic rock arises from progressive metamorphism . On the other hand, if it changes to lower energy conditions, it is a regressive metamorphism .
Listed below are some of the main metamorphic rocks:
* Espilita : belongs to basaltic (igneous rocks volcanic with a rich content of iron and magnesium silicates, and with little silica), specifically those altered by means of fluids at high temperatures. It usually has a green or gray color and has no visible crystals, although this may vary. Commonly, the spilite is in the form of padded lava , which is formed underwater when the lava is directed towards the bottom of the sea and solidifies with an appearance similar to that of a cushion;
* Amphibolite : his composition It is mainly based on amphibole minerals (a set belonging to silicates that comes in a wide range of varieties, with different appearances and compositions). This type of metamorphic rock is the oldest of all that have been found, since it is estimated that they can reach 4.3 billion years. With regard to its texture, it is usually rough;
* Anthracite : This is the most metamorphic of the known mineral carbons, as well as the one that contains the most carbon. It exhibits a bright luster and nuances ranging from steel gray to black. If it is not wet and if the ashes are not taken into account, anthracite has in its dough about a 14% from volatile organic compounds (chemical substances with carbon, present in any living element) and a 86% carbon These percentages may vary, decreasing the first and increasing the second;
* Corneana : The name of this metamorphic rock is due to its name in German, Hornfels, which can be translated as "horn-shaped rock". It is a rock of great hardness, able to withstand the action glacial. It originates from the high temperatures of intrusive igneous masses. In general, its grain is fine and has an aspect that mixes shades of dark brown and black parts;
* Quartzite : it is also known by the name of metacuarcita. It is rich in quartz (usually containing it in more than 90% of its structure) and of considerable hardness. It is important to note that there is a sedimentary rock called "quartzarenite", which some people refer to using the name quartzite, wrongly.