Igneous rocks can be both useful and beautiful.
Igneous rock is everywhere, from the continental igneous rock to the bottom of the ocean, and it appears in a multitude of shapes. The study of igneous rocks reveals a wealth of insight about how our planet works, as well as how people depend on it.
Igneous Defined
Igneous rock forms from rock that has melted and then cooled. It differs from metamorphic rock, which is heated and put under pressure but does not melt. Igneous rock that forms above ground is called extrusive whereas igneous rock that forms underground is called intrusive.
Magma versus Lava
When melted rock is underground, scientists call it magma. When the magma erupts to the surface, scientists change the melted rock's name to lava. There are different types of magma and lava, depending on their chemical makeup.
Plate Tectonics
Used to explain certain geological processes, the scientific theory of plate tectonics proposes that Earth has large plates, called lithospheric plates, that move around. Part of what happens because of plate tectonics includes volcanoes and earthquakes, which create fissures through which melted rock erupts.
The Ring of Fire is the name scientists use to describe an area that forms a ring around the Pacific Rim, where active volcanoes are common.
Volcanoes
Volcanoes are openings in Earth's crust through which melted rock, gases, solid materials as well as ash pass through to reach the surface. Scientists distinguish several types of volcanoes, including cinder cone, lava dome, composite cone and shield volcanoes. Scientists are still studying how volcanoes work, such as predict eruptions.
Igneous Minerals
A mineral is something that has an atomic structure that is orderly and repeats itself, occurs in nature and is not a direct result of biological life, such as plants and people. They also have a specific chemical makeup, which can have a degree of variation.
Examples of common igneous minerals include basalt, granite and quartz. Examples of rarer minerals that form in igneous environments include diamond, garnet and beryl. People use granite to build with, quartz for industrial production, and diamond, garnet and beryl for gemstones.
Volcanic Glass
Volcanic glass, at least in one sense of the term, provides another example of igneous rock but is not a mineral. Types of volcanic glass include pumice, scoria and obsidian. Scoria and pumice are full of air bubbles and have a rough texture whereas obsidian looks like regular glass and tends to be black.
Tags: melted rock, igneous rock, rock that, that forms, chemical makeup, diamond garnet, diamond garnet beryl
