This is a hard igneous rock made up of clearly visible crystals of various minerals. A dark-coloured, fine-grained rock. Basalt is one of the main rocks to form the oceanic crust the part of the Earth's surface under the Ocean. When basaltic lava cools down it can form hexagonal columns such as seen in the Giants Causeway in Northern Ireland see top right picture. There are many other kinds of extrusive igneous rocks. 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. Diorite, granite, pegmatite are examples of intrusive igneous rocks. Extrusive igneous rock: These rocks erupt onto the surface resulting in small crystals as the cooling takes place quickly. The cooling rate for a few rocks is so quick that they form an amorphous glass. Basalt, tuff, pumice are examples of extrusive igneous rock. For instance, igneous rocks after being subjected to extremely high pressure result in metamorphic rocks.
Here, we will focus on the basics of igneous rocks and their uses. What are Igneous Rocks? Igneous rocks are formed from the hot, molten material magma present under the earth crust. Cooling of magma leads to the formation of igneous rocks. Begin typing your search term above and press enter to search. Press ESC to cancel. How does crystal size relate to how long the rock took to cool? What is obsidian? What are some types of intrusive igneous rocks?
What is rhyolite? What is granite? How are igneous rocks classified and differentiated from each other? Why igneous rocks are hard? Why do igneous rocks have crystals?
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