1. Extrusive Igneous Rocks:
* Lava Flows: These are the most common type of volcanic rock. As lava cools quickly on the Earth's surface, it forms fine-grained rocks like:
* Basalt: A dark-colored, dense rock with a fine texture.
* Andesite: A gray or brown rock with a slightly coarser texture than basalt.
* Rhyolite: A light-colored, often glassy rock with a very fine texture.
* Pyroclastic Rocks: These form from explosive eruptions that blast ash, cinders, and larger rock fragments into the air:
* Tuff: A rock made up of consolidated volcanic ash.
* Breccia: A rock made up of angular fragments of volcanic rock.
* Agglomerate: A rock made up of rounded volcanic fragments.
2. Intrusive Igneous Rocks:
* Plutons: These are large bodies of magma that cool slowly underground. They often form:
* Granite: A light-colored, coarse-grained rock, often found as batholiths (huge bodies of granite).
* Diorite: A medium-colored, coarse-grained rock.
* Gabbro: A dark-colored, coarse-grained rock.
The type of rock a volcano produces depends on the type of magma it erupts:
* Basaltic Magma: Typically produces lava flows, basalt, and sometimes agglomerate.
* Andesitic Magma: Produces a mix of lava flows, andesite, pyroclastic rocks, and sometimes tuff.
* Rhyolitic Magma: Produces more explosive eruptions, resulting in ash, tuff, and rhyolite.
So, a volcano can have a mix of different rocks, depending on its history and the composition of its magma.
