Earth crust, i.e., that solid, stone shell of the Earth, on which we live, is a relatively thin crust on the surface of our planet. Magma is a molten rock mass saturated with various hot gases and superheated water vapor. In her area, very high temperatures dominate and colossal pressures: the earth's crust is solidified solid magma. It formed when it solidified, like a foam on milk. All minerals and rocks Earth was ultimately born from magma.

Magma is a molten rock mass saturated with various hot gases and superheated water vapor

Magma contains chemical elements in the state of compounds, as if dissolved in each other. The temperature and pressure inside it, and therefore the content of gases and vapors in it and its chemical composition do not remain unchanged. If the magma rises from the depths to the surface of the Earth, the conditions change, the temperature drops, the pressure decreases, and it begins to solidify, forming solid minerals and rocks, almost always crystalline.

When solidified in magma, complex physical and mechanical processes occur, as a result of which it breaks up into a series of chemical compounds. Some compounds harden earlier, others later, so magma is divided into sections, forming various rocks. In the remaining molten mass, water vapor and volatile compounds accumulate. These parts of magma fill the cracks of the earth's crust, slowly solidify there and form minerals. Part of the volatile compounds rises higher, to the earth's surface, in the form of gas jets, and water vapor condenses into water, forming solutions of magma residues. These solutions flow through the cracks, gradually cooling and releasing one after another various minerals depositing along the walls of the cracks; so there are mineral "veins".

There are the following varieties of magma: basaltic, apparently, is more common. It contains about 50% silica, a significant amount of aluminum, calcium, iron and magnesium, in smaller - sodium, potassium, titanium and phosphorus. In terms of their chemical composition, basaltic magmas are subdivided into tholeitic (oversaturated with silica) and alkali-basalt (olivine-basalt) magma (under-saturation with silica, but enriched in alkalis).

Granite magma contains 60-65% of silica, it has a lower density, more viscous, less mobile, more than basaltic is saturated with gases. Depending on the nature of the movement of the magma and the place of its solidification, there are two types of magmatism: intrusive and effusive. In the first case, magma cools and crystallizes at depth, in the bowels of the Earth, in the second - on the earth's surface or in near-surface conditions (up to 5 km).