Igneous Rocks Formation and Classification

Study Notes

Igneous rocks derive their name from the Latin word "ignis," meaning fire.
They are formed by the cooling and solidification of hot, molten rock (magma).
Magma can solidify either below the surface of the Earth (intrusive) or on the surface (extrusive).
Intrusive igneous rocks, formed below the surface, cool slowly, allowing larger mineral crystals to develop.
Extrusive igneous rocks, formed on the surface, cool quickly, resulting in smaller or no visible mineral crystals.
The rate of cooling significantly impacts the texture and mineral composition of the resulting rock.
Different types of igneous rocks exhibit unique characteristics based on their composition and cooling history.
The mineral content in magma determines the resulting igneous rock type.
Factors like the amount of silica present influence the properties of the rock.
Various classifications exist for igneous rocks, based on factors such as their composition and texture.
Common examples of igneous rocks include granite, basalt, obsidian, and pumice.
Granite is a common intrusive igneous rock, characterized by visible crystals.
Basalt is an extrusive igneous rock, often dark in color.
Obsidian is a glassy, extrusive igneous rock formed from very rapid cooling.
Pumice is a light and porous extrusive igneous rock.
The formation of igneous rocks plays a critical role in the Earth's geological processes.