Which of the following is an example of extrusive igneous rock?

Which of the following is an example of extrusive igneous rock? Correct Answer Basalt

The correct answer is Basalt.

Key Points

• ​Basalt is a dark-colored, fine-grained, igneous rock.
• Basalt is an extrusive igneous rock formed by the rapid cooling of lava.
• Basalt is rich in iron and magnesium and is mainly composed of olivine, pyroxene, and plagioclase. 

Important Points

• Igneous rocks are formed when molten material from within the Earth, called magma, cools down and solidifies forming crystals.
• They are characterized by an interlocking crystalline texture.
• Igneous Rocks mainly are of two types:
  • ​Intrusive rocks:
    • ​Intrusive (plutonic) rocks form when magma solidifies within the crust below the surface.
    • It usually cools slowly and produces large crystals. 
    • Examples of intrusive igneous rocks are diabase, diorite, gabbro, granite, pegmatite, and peridotite.
  • Extrusive rocks
    • Extrusive (volcanic) rocks form when magma erupts onto the surface of the Earth as lava flows, and usually cools quickly producing small crystals.
    • It can also erupt explosively as ash.
    • Extrusive igneous rocks erupt onto the surface, where they cool quickly to form small crystals.
    • Some cool so quickly that they form an amorphous glass.
    • These rocks include Andesite, Basalt, Dacite, Obsidian, Pumice, Rhyolite, Scoria, and Tuff.

Additional Information

• Granite: 
  • ​Granite is the most common intrusive rock in Earth’s continental crust.
  • It is familiar as a mottled pink, white, grey, and black ornamental stone. 
  • It is coarse- to medium-grained.
  • Its three main minerals are feldspar, quartz, and mica, which occur as silvery muscovite or dark biotite, or both. 
• Marble:
  • A marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism..
  • It is composed primarily of the mineral calcite (CaCO3) and usually contains other minerals, such as clay minerals, micas, quartz, pyrite, iron oxides, and graphite.
  • Marble is usually a light-colored rock.
  • Marble is of extremely high purity with a bright white color is very useful.