Which one of the following is an example of both an igneous as well as a metamorphic rock?

The correct answer is Granite.

Key Points

• Granite is primarily an igneous rock, formed from the slow crystallization of magma beneath the Earth's surface.
• It is composed mainly of quartz, feldspar, and mica minerals, giving it a granular texture.
• Granite can undergo metamorphism, transforming into a metamorphic rock known as gneiss when subjected to high pressure and temperature conditions.
• During the metamorphic process, the mineral composition of granite may realign to form new structures, but the original minerals may still be identifiable.

Additional Information

• Igneous Rocks:
  • Formed from the cooling and solidification of magma or lava.
  • Examples include basalt, granite, and pumice.
  • Classified into intrusive (plutonic) and extrusive (volcanic) types.
• Metamorphic Rocks:
  • Formed from the alteration of existing rock types in the Earth's crust due to heat, pressure, and chemically active fluids.
  • Examples include gneiss, schist, and marble.
  • Two main types: foliated (with a layered appearance) and non-foliated (without a layered appearance).
• Formation of Gneiss:
  • Gneiss is a high-grade metamorphic rock formed from pre-existing rocks like granite, shale, or volcanic rocks.
  • Characterized by its banded texture resulting from the segregation of mineral layers.
• Geological Significance:
  • Granite is widely used in construction due to its durability and aesthetic appeal.
  • Metamorphic rocks like gneiss provide insights into the geological processes and conditions within the Earth's crust.