How is an igneous rock created (process of formation from magma or lava)?

What this question is asking

You need to explain where igneous rocks come from and the main steps that turn melted rock into solid rock. The key ideas are cooling and crystallization, and how the location of cooling changes the rock’s texture.

Step-by-step formation of igneous rock

1. Rock melts to form magma: Deep inside Earth, existing rock can melt due to high temperatures (often helped by pressure changes or the addition of water). The melted material is called magma.
2. Magma moves upward: Magma is less dense than surrounding rock, so it can rise through cracks and collect in magma chambers.
3. Cooling and solidification: When magma or lava cools, minerals start to form crystals. This change from liquid to solid is solidification, and crystal growth is crystallization.

Intrusive vs. extrusive igneous rocks (why cooling rate matters)

• Intrusive (plutonic) igneous rocks form when magma cools underground. Cooling is slow, so crystals have time to grow large. Result: coarse-grained texture (example: granite).
• Extrusive (volcanic) igneous rocks form when lava cools at Earth’s surface after an eruption. Cooling is fast, so crystals stay very small, or the rock can cool into volcanic glass. Result: fine-grained or glassy texture (examples: basalt, obsidian).

Why this process matters in the rock cycle

Once formed, igneous rocks can be weathered into sediment, changed by heat and pressure into metamorphic rock, or even melted again to make new magma. So igneous formation is one of the main starting points in the rock cycle.