Basalt belongs to volcanic igneous rocks family. It is a dark-colored (black, dark green or brown) rock with a fine-grained outlook. Basalt is the most common rock found on earth’ crust. Basalt’s composition is similar to gabbro but gabbro is a coarse-grained rock.
The silica (SiO2) content in Basalt is 45%-52%. It also contains other minerals like pyroxene, plagioclase and olivine. Some specimens also contain glass in trace amounts. Basalt has a aphanitic, which can be porphyritic.
Basalt Rock Formation
The majority of basalt was formed as a result of three events; oceanic divergent boundaries, oceanic hotspots, and mantle plumes and hotspots beneath continents.
Also Read: Dacite Rock Type, Composition, Formation, Occurrence & Uses
Where is Basalt Found?
Basalt is found in enormous quantities under the sea. It is also found above the sea level. Hawaiian Islands are an example of basaltic volcanoes above the oceanic hotspot. The flood basalts on land include the Columbia River Flood Basalt in Washington, Oregon, and Idaho. The flood basalts are also found at the following areas.
- Emeishan Traps of China
- Deccan Traps of India
- Keweenawan Lavas of the Lake Superior region
- Etendeka Basalts of Namibia
- Karoo Basalts of South Africa
- Siberian Traps of Russia
- Columnar basalt flows in Yellowstone National Park, USA.
Basalt is also found in large quantities on moon. A major part of moon’s surface is underlain by basaltic lave flows and flood basalts. These areas are known as “Lunar Maria”. Recent research has highlighted the possibility that volcanoes on Mars and Venus are also made of Basalt.
Types of Basalt
- Tholeiitic basalt
- High and low titanium basalts
- Mid-ocean ridge basalt (MORB)
- High-alumina basalt
- Alkali basalt
It would be hard to imagine our current living style without basalt. Basalt is commonly used as an aggregate in construction projects. It is crushed to use for road base, concrete aggregate, asphalt pavement aggregate, filter stone for drain fields, and railroad stabilizer. Basalt is heated and extruded to yield stone wool, which is an excellent thermal insulator.
Basalt is also used as floor tiles, building veneer, monuments, sculptures and stone objects. It is cut into dimensional stones and thin slabs to increase its usability for daily life. The most famous monument build from basalt is the Roman Theatre in Bosra, Syria. Basalt paving stones were often used in areas near to volcanoes. You can still find many city streets made with Basalt in Rome, Italy.
Many people use basalt dust fertilizers for increasing plant growth. It suppresses the growth of weeds. Basalt is also used in construction of wind turbine blades because its tensile strength is higher than carbon fiber/fiberglass.