Some uses of igneous rock include serving as material for buildings and roads. Igneous rocks reduced to gravel size serve as ballast for railroad beds. Igneous rocks are also used for countertops, backsplashes and sinks. They can be carved into works of art and weapons.
Some igneous rocks, such as lamproite, contain gemstones such as diamonds and spinel. Pegmatite, a coarse-grained rock very much like granite, contains useful minerals and elements such as boron and lithium. Beryl and tourmaline can also be found in pegmatite.
Granite, a hard rock that's formed by magma that has slowly cooled in the Earth's crust, is sought after not only for its toughness but its beauty. It can come in colors of white, red, pale greens and blues, grays, blacks and violet. Because of this, it is prized for home decoration and is used for flooring, countertops and table tops.
Basalt is the most common igneous rock and forms much of the seabed. It's often black, but can be gray, brown, pale green or red. Ancient Egyptians used basalt as an ornamental stone.
Obsidian forms when thick, hot lava cools quickly, before the minerals have a chance to crystallize. This gives the rock a glassy texture. Prehistoric people used obsidian to make sharp points and blades.Learn More
Grain size is one of the classification methods used when identifying igneous rocks. They are also classified by the silica content or silica saturation. Other methods of classification include the total alkali versus silica scheme and the International Union of Geological Sciences scheme.Full Answer >
Rocks are important because geologists use evidence from them to learn about what the Earth was like in the past. They allow scientists to build a historical record of the planet to learn what events occurred before people lived.Full Answer >
Rocks come from magma, which is the molten material found within the earth. When magma cools, either above or below the earth's surface, it crystallizes and forms the igneous rocks that can later be changed into metamorphic or sedimentary rocks. Magma, which can be considered molten rock, is referred to as lava when it reaches the earth's surface.Full Answer >
Humans use rocks for a wide variety of purposes, including construction and as a source of valuable minerals located inside the rocks. Additionally, humans use rocks for decoration, recreation and thermal purposes. Humans are not the only organisms that utilize rocks, as plants, animals and fungi use rocks for stability, digestive purposes and as a substrate.Full Answer >