What is basalt?

Basalt is the most widespread magmatic rock on the surface of the Earth and other planets (such as for instance, the Moon, Mars, Venus and even the asteroid Vesta). Most basalt rocks are formed in ocean mountain ridges and make up the ocean crust. Basalts are also typical for continents. Under the continents basalt lies up to 31 km, and under the oceans – from 6 km and more.

The word “basalt” is of ancient origin. In Ethiopian it means “dark”, “black”.

Basalt is usually dark grey, but it can also be green, brown or black.

The structure of basalt depends on the process of magma crystallization and the time of rock formation.

Basalt is usually of a columnar form. It is a result of uneven cooling of the rock. Most probably, in the process of cooling Benard cells are formed in the liquid rock, which when cooled and chemically weathered, transform into separate (5 or 6 angular) columns.

Oceanic basalt has the form of a pillow. It is the result of rapid water cooling of the lava. Magma lifts up the already formed shell, flows from under it and forms the next pillow.

Depending on the SiO2 content, all basalt rocks are divided into three groups: basic, neutral and acidic. It is worth noting that basalt rock samples brought from the Moon belong to the group of basic basalts.

Basalt deposits are concentrated in Armenia, Eastern Siberia, and the Far East. Basalt spathes in the eastern areas of the USA form huge deposits in the states of New-York, New Jersey, Pennsylvania, and Connecticut. On the territory of Ukraine, basalt is widely spread in Rivne, Zakarpattya, and Donetsk regions.