Igneous rocks are formed from the solidification of molten rock material. They can be classified into two main categories: intrusive (plutonic) and extrusive (volcanic). Here are some examples of each type:
Intrusive Igneous Rocks:
- Granite: A coarse-grained rock primarily composed of quartz, feldspar, and mica. Commonly used in construction.
- Diorite: A medium-grained rock with a composition between granite and gabbro, often featuring a mix of light and dark minerals.
- Gabbro: A coarse-grained rock rich in iron and magnesium minerals, typically dark in color.
- Pegmatite: Extremely coarse-grained rock that can contain large crystals of quartz, feldspar, and other minerals, often associated with mineral deposits.
- Peridotite: A dense, dark rock composed mainly of olivine and pyroxene, typically found in the Earth's mantle.
Extrusive Igneous Rocks:
- Basalt: A fine-grained, dark rock that is the most common volcanic rock on Earth, often found in oceanic crust and volcanic islands.
- Rhyolite: A fine-grained, light-colored rock that is typically associated with explosive volcanic eruptions.
- Andesite: A fine-grained rock with an intermediate composition between basalt and rhyolite, commonly found in volcanic arcs.
- Pumice: A light, porous rock formed from rapidly cooling lava that contained gas bubbles, often used as an abrasive material.
- Obsidian: A naturally occurring volcanic glass that is smooth and shiny, formed from rapidly cooled lava.
These examples highlight the diversity of igneous rocks in terms of their composition, texture, and formation processes.