What is Magma: Definition. What is magma and lava?

"Mash, or thick ointment" (in Greek), it is a molten molten glowing rock of silicate nature. That's what magma is. It occurs in the earth's crust, in the upper mantle, at great depths. And with its cooling it forms characteristic rocks.

What is magma? Definition in dictionaries

In various sources, the word "magma" is interpreted as a mass of molten rock, located under hard earth. They also indicate its silicate composition and the ability to form magmatic rocks.

Origin

The fact is that the globe is hot inside. The heat melts terrestrial rocks, which as a result are inside in a liquid state. What is magma? It is a liquid stone enclosed in a harder surrounding shell. It by weight is much lighter than this shell. Therefore, it rises upward under the emerging pressure. Sometimes magma does not erupt out, gradually cooling down somewhere deep underground and hardening. So for millennia mountains are formed. Sometimes hard and colder rocks can not withstand the high pressure of the magma from the inside. There are faults through which the magma breaks out, pours out. She, while still in a liquid state, spreads on the ground.

What happens then

What is magma that has come to the surface of the earth? It is called lava. After the magma erupted outside, it immediately begins to cool, interacting with the external environment and the surrounding atmosphere. It happens pretty quickly. Some of the substances that make up it harden faster than others, forming crystals. These crystals seem to float in a liquid rock. And the largest of them form the mountains of lava. All these mountains are made up of numerous crystals embedded in basalt. They are called porphyry.

Chemical composition

What is magma in terms of science of chemistry? This liquid rock contains many chemical elements. Among them, magnesium, sodium, iron, potassium. And also - volatile components: chlorine, fluorine, hydrogen and others. And such a component as water vapor. As you exit the surface, volatile elements (their number) are reduced, the process of degassing takes place.

Classification

• Basaltic (basic). It contains silica (up to 50%), magnesium, iron, aluminum, calcium in a large amount. In a smaller volume - titanium and phosphorus, potassium and sodium.
• Granite (acidic, rhyolite). Contains silica (up to 65%). It is more saturated with gases, has a lower density than basalt.
• According to the nature of advancement and the way of solidification, several types of magmatism are distinguished. Intrusive type - magma freezes, crystallizes deep in the interior, without leaving the surface. Effusive type - magma erupts to the surface and freezes already there.

The solidification process

The magma melt consists of liquids, gases, solid crystals that are in a certain equilibrium state. Under the influence of the environment, the volume of magma tends to evolve. Some crystals of minerals melt, others - reappear.

What does magma mean? This is a rather complex solution in which the precipitation of solid crystals obeys physical and chemical laws. But even in the same magma the composition sometimes changes under the influence of temperatures and pressure.

The flow rate of the flowing magma sometimes reaches 30 km / h, the temperature - up to 1250 degrees. In liquid form, the magma remains at a temperature of about 600 degrees, and then begins to solidify.

At the same time, minerals crystallize and concentrate on separate areas of advance, forming endogenous deposits of iron, non-ferrous and precious metals, and diamonds. These magmatic formations arise in layered rock complexes.

What is magma and lava?

As already mentioned, lava is an erupting magma, consisting of a viscous melt of rocks, predominantly silicate ones. The main difference between the first and the second is that there are no gases in the lava that evaporate when the liquid stone exits. Lava tends to cool and freeze over time, stopping its progress. As a result, lava rocks are formed: mountains and even plateaus. Different lava volcanoes differ in composition, temperature, and other characteristics. For example, carbonate lavas are brittle, soft, easily soluble in water.

Volcanic eruptions

It only seems to us that the Earth inside is firm and immovable. In fact, deep inside, there is a constant movement of molten substances - magma. It seeks to reach the surface through all sorts of cracks and canals that arise in the crust of the Earth. So there are volcanoes - the magma that has found its way out erupts, sweeping everything in its path. Of the most famous eruptions (recorded by science), one can note the release of magma on the island of Krakatau in 1883. As a result, the island was completely destroyed. The eruption claimed more than 200 thousand lives!