1. Igneous Rocks:
* Formation: Formed from the cooling and solidification of molten rock (magma or lava).
* Characteristics: Often have a crystalline texture due to slow cooling and can be classified as intrusive (cooled underground, e.g., granite) or extrusive (cooled above ground, e.g., basalt).
* Examples: Granite, basalt, obsidian, pumice
2. Sedimentary Rocks:
* Formation: Formed by the accumulation and cementation of sediments (rock fragments, mineral grains, or organic matter).
* Characteristics: Often layered, contain fossils, and can be classified as clastic (made of rock fragments), chemical (formed from precipitation of minerals), or organic (formed from organic matter).
* Examples: Sandstone, limestone, shale, coal
3. Metamorphic Rocks:
* Formation: Formed when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are transformed by heat, pressure, or chemically active fluids.
* Characteristics: Often have a foliated (layered) texture or a non-foliated texture, depending on the pressure and heat involved.
* Examples: Marble (from limestone), slate (from shale), gneiss (from granite), quartzite (from sandstone)
In summary:
* Igneous rocks are born from fire, directly from molten rock.
* Sedimentary rocks are built up over time from the accumulation and cementing of smaller pieces.
* Metamorphic rocks are transformed from pre-existing rocks through intense heat and pressure.
Each type of rock has its own unique characteristics and formation process, contributing to the fascinating diversity of the Earth's crust.
