The magmatic texture is the overall appearance of an igneous rock based on the size, shape and arrangement of their windows.
Plutonic texture. All the minerals are crystallized. The crystal size is the same, roughly. This type of texture indicates that the magma is cooled very slowly, over millions of years have had enough crystals to grow.
Porphyritic texture. It consists of large crystals (phenocrysts) surrounded by other microscopic crystals, thin and elongated (microliths). Have formed in an amorphous vitreous paste. Critaliza in two phases:
In the first, slow cooling, crystallizing phenocrysts.
In the second, rapid cooling, crystallize the pasta and microliths.
Extruded O VOLCANIC ROCKS
Extrusive volcanic rocks have a porphyritic texture and glass. Eg basalt, andesite and pumice.
Pluto: It is characterized by plutonic texture, as they have formed very slowly at great depth. Eg Granite, syenite, gabbro, Perioditita.
Philonian rocks are intermediate between the plutonic and volcanic, as consolidated in the Earth's interior, but in areas relatively close to the surface. Eg porphyry and pegmatite.
USES OF ROCKS
Humans carry mules years using the rocks as materials to form, sculpting or for making useful and ornamental objects.
The marble used in construction and sculpture.
The granite used in construction of buildings, monuments and paving
Quartzite is used in the construction of buildings, roads, walls and floors.
Slate is used in walls and roofs of buildings.
Metamorphic rocks are formed in solid state by physical and chemical changes as a result of pressure and temperature variations inside the Earth.
The process that causes this kind of rock is called metamorphism, and may last millions of years.
The factors controlling metamorphism and can transform a sedimentary rock, igneous and metamorphic rock in a metamorphic rock are:
Temperature. The temperature increase occurs when the materials are close to a magma or are deeply buried, as the temperature increases 1 ° every 33 meters.
Pressure. The rocks are buried under two forces: that exercised by the materials placed on them (lithostatic pressure) and generates the collision of lithospheric plates (directed pressure) leading to the great ranges.
Fluids. When the pressure and temperature fluids found in the pores of the rocks are released, react with minerals and changes in the composition of the rock.
CHANGES ON THE ROCKS WITH THE METAMORPHISM
The effects of metamorphic rocks are reflected on the chemical composition and texture:
Mineralogical changes. When the pressure and temperature, minerals vuenven unstable. After a series of chemical reactions, are converted into other minerals, metamorphic minerals called stable in the new conditions.
Changes in texture. With increasing pressure, the levels of a rock minerals are reoriented and are lineados perpendicular to the direction of the force. Mineral alignment gives the rock a banded appearance or leafy, known asfoliation. The foliation in fine-grained rock called slate, and rocks with larger crystals, cleavage.
TYPES OF METAMORPHISM
Metamorphism occurs where rocks are subjected to different conditions of their formation. In response thereto, unstable rocks change gradually, to reach equilibrium with the new environment,
There are three main types of metamorphism: pressure metamorphism, contact metamorphism and regional metamorphism.
Regional metamorphism occurs when rocks are subjected simultaneously to an increase in pressure and temperature. Occurs, for example, in the process of mountain building
Regional metamorphic origin
In large sedimentation basins, sedimentary rocks undergo a progressive regional metamorphism, the more intense with increasing depth.
As a result, they form a series of metamorphic rocks, which we see a range of transformations that progressively increase. The most famous series is the clay, which include slate, schist and gneiss, which differ by their degree of metamorphism.
Thermal metamorphic origin
The most important are marble and quartzite.