What are the three main groups of rocks?
Rocks can be conveniently placed into one of three groups or types – igneous, sedimentary, and metamorphic. Igneous rocks Igneous rocks, such as granite, pegmatite, rhyolite, obsidian, gabbro, and basalt, are formed by the solidification of molten magma that emerges through Earth’s crust via volcanic activity. The nature and properties of the crystals vary greatly, […]
