Igneous
Definition
Rocks or minerals formed from the cooling and solidification of molten magma or lava.
Example
Quartz often forms in igneous rocks like granite.
Born from Fire
Igneous rocks (from the Latin "ignis" meaning fire) form from the cooling and solidification of molten rock. This molten rock is called <strong>magma</strong> when it is underground and <strong>lava</strong> when it erupts onto the surface. Igneous rocks are the ancestors of all other rocks; the Earth's first crust was entirely igneous.
Intrusive vs. Extrusive
- Intrusive (Plutonic): Magma cools slowly deep underground. This slow cooling allows large crystals to grow. Examples include Granite and Pegmatites (where large gemstones like Tourmaline and Beryl form).
- Extrusive (Volcanic): Lava cools rapidly on the surface. Crystals don't have time to grow large, resulting in a fine-grained or glassy texture. Examples include Basalt and Obsidian (volcanic glass).