What are the differences between the three types of rocks: igneous, sedimentary, and metamorphic?

Igneous, sedimentary, and metamorphic rocks are the three main types of rocks that make up the Earth's crust. Each of these rocks has a different formation process, mineral composition, and physical properties.

Igneous Rocks

Igneous rocks are formed from solidification and cooling of magma or lava. They can be either intrusive or extrusive. Intrusive igneous rocks form when magma cools slowly beneath the Earth's surface, while extrusive igneous rocks form when lava cools quickly on the Earth's surface. Some common examples of igneous rocks are granite, basalt, and pumice.

Sedimentary Rocks

Sedimentary rocks are formed from the accumulation and lithification of sedimentary particles such as sand, clay, and organic matter. They can be further divided into three subcategories: clastic, chemical, and organic. Clastic sedimentary rocks are formed from the accumulation and lithification of rock fragments and minerals, such as sandstone and shale. Chemical sedimentary rocks are formed from the precipitation of minerals from water, such as limestone and halite. Organic sedimentary rocks are formed from the accumulation and lithification of organic matter, such as coal and oil shale.

Metamorphic Rocks

Metamorphic rocks are formed from the alteration of existing rocks due to heat, pressure, and chemical processes. They can be either foliated or non-foliated. Foliated metamorphic rocks have a layered or banded appearance due to the alignment of minerals, such as slate and gneiss. Non-foliated metamorphic rocks do not have a layered or banded appearance, such as marble and quartzite.