1. Igneous Rocks:

* Formation: Formed from the cooling and solidification of magma (molten rock beneath the Earth's surface) or lava (magma that has erupted onto the Earth's surface).

* Intrusive igneous rocks: Form when magma cools and solidifies slowly underground, resulting in larger crystals (e.g., granite).

* Extrusive igneous rocks: Form when lava cools and solidifies quickly on the Earth's surface, resulting in smaller crystals (e.g., basalt).

2. Sedimentary Rocks:

* Formation: Formed from the accumulation, compaction, and cementation of sediments (rock fragments, mineral grains, or organic matter) that have been transported and deposited by wind, water, ice, or gravity.

* Clastic sedimentary rocks: Composed of fragments of other rocks (e.g., sandstone, shale).

* Chemical sedimentary rocks: Formed from the precipitation of minerals out of water (e.g., limestone, rock salt).

* Organic sedimentary rocks: Formed from the accumulation of organic matter, like plant or animal remains (e.g., coal, oil shale).

3. Metamorphic Rocks:

* Formation: Formed when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are transformed by heat, pressure, or chemically active fluids. This transformation doesn't melt the rock completely, but changes its mineral composition and texture.

* Foliated metamorphic rocks: Have a layered or banded appearance due to the alignment of minerals under pressure (e.g., slate, schist).

* Non-foliated metamorphic rocks: Have a more uniform texture without distinct layering (e.g., marble, quartzite).

Remember that the rock cycle shows how these three types of rocks are interconnected and can transform from one type to another over time.