* Igneous rocks form from the cooling and solidification of molten rock, either magma (underground) or lava (above ground). They are essentially "brand new" rocks, created directly from a liquid state. Examples include granite, basalt, and obsidian.
* Metamorphic rocks form from existing rocks (igneous, sedimentary, or even other metamorphic rocks) that have been transformed by heat, pressure, and/or chemical reactions deep within the Earth's crust. They are "recycled" rocks, their original composition and structure changed by these intense conditions. Examples include marble, slate, and gneiss.
Here's a table summarizing the key differences:
| Feature | Igneous Rocks | Metamorphic Rocks |
|---|---|---|
| Formation | Cooling and solidification of magma or lava | Transformation of existing rocks by heat, pressure, and/or chemical reactions |
| Origin | Molten rock | Existing rocks |
| Texture | Crystalline, glassy, or fragmental | Foliated (layered) or non-foliated |
| Examples | Granite, basalt, obsidian | Marble, slate, gneiss |
So, while both types of rocks are found in the Earth's crust, their origins and formation processes are distinct, leading to noticeable differences in their appearance, composition, and properties.
