What is the Difference Between Igneous Rocks and Metamorphic Rocks?

Igneous and metamorphic rocks are two of the three main types of rocks, with sedimentary rocks being the third type. They differ in their origin, texture, and mineral composition. Here are the main differences between igneous and metamorphic rocks:

1. Origin: Igneous rocks are formed from the cooling and solidification of magma or lava, which is molten rock found beneath the Earth's surface. Metamorphic rocks, on the other hand, are formed from the transformation of existing rocks, such as sedimentary or igneous rocks, through a process called metamorphism, which is caused by heat and pressure.
2. Formation Process: Igneous rocks form through the cooling and solidification of magma or lava, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. Metamorphic rocks are formed when sedimentary, igneous, or pre-existing metamorphic rocks are changed by environmental factors such as heat, pressure, or reactive fluids.
3. Texture: Igneous rocks can have a crystalline or glassy texture, depending on the cooling rate of the magma. Metamorphic rocks have a more diverse texture, as they are the result of changes in the original rock.
4. Mineral Composition: Igneous rocks are generally made up of two or more minerals. Metamorphic rocks, in contrast, can be composed of only one mineral or a combination of minerals, depending on the original rock and the conditions of metamorphism.
5. Resistance to Weathering and Erosion: Igneous rocks generally have a higher resistance to weathering and erosion compared to metamorphic rocks.
6. Reactivity with Acids: Metamorphic rocks tend to have a higher tendency to react with acids compared to igneous rocks.

In summary, igneous rocks are formed from the cooling and solidification of magma or lava, while metamorphic rocks are formed from the transformation of existing rocks due to heat and pressure. These differences in origin lead to distinct differences in texture, mineral composition, and other properties between the two types of rocks.

Comparative Table: Igneous Rocks vs Metamorphic Rocks

Here is a table highlighting the differences between igneous rocks and metamorphic rocks:

Igneous rocks are formed from melted rock deep inside the Earth, while metamorphic rocks are formed from the transformation of existing rocks through heat and pressure. The texture and mineral composition of these rocks also differ, with igneous rocks having a smooth, glassy, or crystalline texture and metamorphic rocks having a foliated or non-foliated texture.