Which rocks are products of volcanic eruptions

Volcanoes for schoolchildren

Volcanic extraction products

What reaches the surface of the earth during a volcanic eruption depends on the chemical composition of the magma. The magma is molten rock and contains different amounts of gas and water. When a volcanic eruption occurs, most of the gas escapes from the magma. When the low-gas magma reaches the surface of the earth, it is called lava. The lava cools down on the surface of the earth and becomes solid rock again. Depending on the composition of the magma, different types of rock arise from the lava. Basalt is the most common type of rock made from lava. As long as this rock is still melted, it is very thin. It looks completely different with the rock rhyolite. As lava, it is very viscous and does not flow well.

Tephra
During explosive volcanic eruptions, lava fragments of different sizes are thrown out of the volcano.
The smallest particles of the tephra are as small as grains of sand and are called ashes. In an eruption cloud, they rise up to 30 kilometers into the sky and are blown away by the wind. The slightly larger stones come down near the volcano. They are the size of pebbles and are called lapilli. The large chunks and blocks fall to the ground near the crater. Since some of them are still glowing hot and soft, they often take on an egg-shaped shape in the air. Then there are the volcanic bombs.
Ash, lapilli, blocks and bombs together make up the tephra. Cooled tephra looks like the slag from a blast furnace.

Lava flows
When a lava flow cools, a solid layer of rock forms. Depending on how fast the lava cools, a cooled lava flow can form wonderful columns. Some lava looks like it's made of ropes or ropes.


Image: Stricklava

Water and gas
The most valuable thing volcanoes produce is water. It comes out of the volcanoes as white vapor. When the clouds of water vapor cool down, liquid water is created, which falls on the earth as rain. The gas carbon dioxide also comes from volcanoes. Plants turn carbon dioxide into oxygen, which we need for life. It also regulates the temperature of the atmosphere. Too much carbon dioxide is harmful, because then it can get too warm on our earth. It is not the volcanoes that are to blame for the current warming, but the people who pollute the environment with exhaust gases.

Precious stones and metals
Valuable gemstones and rare metals have often been found in volcanic rocks. On the Kamchatka Peninsula, for example, there are volcanic rocks that contain gold.