Mineralogy. Endogenic processes of minerogenesis.

Endogenic processes always are anyhow bound to magma activity. Among them ooze:

Magmatic processes. At what minerals are formed immediately at magma crystallisation concern naturally magmatic processes of minerogenesis. So there were all minerals composing magmatic rocks.

As is known from a course of blanket geology, magmatic rocks are divided on two major groups: intrusive, crystallised on depth, and effusive, formed close or on an earth surface. Magmatic processes of minerogenesis can be related both to intrusions and with effusions

Pegmatitic process. At crystallisation of granite magma, the residual silicate melting rich with linkings rare and rare-earth of elements and flying substances - mineralizers is formed. This silicate melting is implanted in adjacent strata, fills in them fractures and vacuities and, crystallising, forms venous coarse-cristalline bodies - pegmatites.

Pegmatites are rich with various minerals. Except main rock-forming minerals - a microwedge, plagioclases and biotite - often there are tourmalins, for some pegmatites beryl, a spodumene and many other things are characteristic.

Pegmatitic lodes can reach several kilometres in length and several tens metres of power. Minerals of pegmatites also reach the major sizes.

Pegmatites often have a zone structure, and different minerals are dated for different bands.

Pneumatolytic process. Pneumatolysis - process of formation of minerals of a gas phase. At some stages of crystallisation of magma probably separation of gases. In process of a motion hill up on fractures these gases are cooled, react with each other and with adjacent strata therefore minerals are formed. Pneumatolytics (pneumatolysis yields) are divided on volcanic and deep.

Volcanic pneumatolytics are formed in volcanic fields for the account of the gases separating from magma close or on a surface of the earth. Volcanic gases in large quantities leave in atmosphere through muzzles of volcanoes, fumaroles and fractures.

In the course of a gas fume in fractures of laval covers and craters of volcanoes there is a formation of minerals. Preferentially it is chlorides and sulphates - minerals, easily miscible and consequently not observed in considerable quantities. Usually all minerals formed at volcanic activity, look like touches, microcrystallitic crusts or earthy units.

To the volcanic fumes related to basalt magma, it is possible to carry accumulations of sulphides at the bottom of the East Pacific raising (on depth about 2.5 km). In a spreading band actively operating volcanic muzzles which are throwing up firm particles and fluids with temperature 350-400°С are discovered. On "the vent areas" sulphidic hills in height to 10 m. are formed

Accumulations of sulphides most probably are formed thanks to a reduction of sulphate of ocean water during its circulation, and also thanks to mobilisation of substance of basalts.

Deep pneumatolytics are formed in that case when gases separate from the magmatic centre in earth crust entrails. They percolate through rocks, react with them, converting their chemical and mineral composition. The degree of chemical transformations of soils under the influence of gases depends on their chemical activity, a composition of soils, a tectonic structure and duration of process.

Hydrothermal process. Hydroterms - the hot water solutions separating from magma or formed as a result of liquation of gases.

The parent of a motion a hydroterm - a difference of pressures. When interiorly pressure of solutions more exterior, solutions running towards the least pressure, usually hill up, to an earth surface. At the motion they use various tectonic disturbances, fractures, bands of contacts. In process of removal of solutions from the magmatic centre their temperature impinges. As a result of temperature drop and responses with adjacent strata hydroterms deposit the load in the form of minerals. Eduction of minerals from water solutions also represents essence of hydrothermal process.

As hydroterms usually running on fractures, the shape of the majority of hydrothermal mineral bodies the venous. The pivotal venous mineral is quartz.