Question

Compare rock types.

Answer 1

Basis	Igneous Rocks	Sedimentary Rocks	Metamorphic Rocks
Formation	Igneous rocks are formed by the cooling and solidification of magma or lava.	Sedimentary rocks are formed by the deposition, compaction and cementation of sediments.	Metamorphic rocks are formed when existing rocks change due to heat and pressure.
Structure	Igneous rocks are generally hard, compact and crystalline in structure.	Sedimentary rocks are usually arranged in layers and may be comparatively soft.	Metamorphic rocks are generally hard and may show bands or layers.
Fossils	Fossils are generally not found in igneous rocks.	Fossils are often found in sedimentary rocks.	Fossils are usually absent or altered in metamorphic rocks.
Porosity	Igneous rocks are generally less porous or non-porous.	Sedimentary rocks are often more porous than igneous rocks.	Metamorphic rocks are generally less porous and compact.
Examples	Basalt and granite are common examples of igneous rocks.	Sandstone and limestone are common examples of sedimentary rocks.	Marble and slate are common examples of metamorphic rocks.
Uses	Igneous rocks are used for constructing roads, buildings and monuments.	Sedimentary rocks are used for construction and for making cement.	Metamorphic rocks are used for sculptures, flooring and decorative work.