Three Major Types of Rocks
Igneous
Igneous rocks are either formed from magma (molten rock) that has solidified underground, creating intrusive rocks such as granite, or has flowed onto the lands or seabed, forming extrusive rocks such as basalt.
Basalt
Granite
Sedimentary
Most sedimentary rocks, such as sandstone, are made of deposits laid down on the Earth’s surface by wind, water, or ice.
Travertine Limestone
Limestone
Onyx
Slate
Sandstone
Metamorphic
Metamorphic rocks are formed when the mineralogical composition of existing rocks is altered. Quartzite, for example, is metamorphosed sandstone
Quartzite
Marble
Gneiss