Science Snapshot: Igneous Rocks

As a kid, igneous rocks were always my favorite type of rock because of the big sparkly crystals that are characteristic of igneous rocks. The aragonite mineral in the image above was formed from magma cooling very slowly deep inside the earth. The beautiful, crystal-lined igneous rocks are composed of one or more types of minerals combined into one rock. However, not all igneous rocks are made of shiny flawless mineral crystals. Igneous rocks suffer from multiple personality disorder. They can have a wide range of characteristics such as shiny, dull, rough, smooth, glassy, heavy, and light. It all boils down to where the molten rock cooled and how fast it cooled. Like my wife says about women, igneous rocks are not complicated, they are just multifaceted!

Molten rock that cools slowly deep inside the earth forms large crystals. The slower the cooling, the larger the crystals. This is known as an intrusive igneous rock. Photo by Jay Merrill.
Molten rock that cools quickly on the surface of the earth forms extrusive igneous rocks. This is pumice, a rough, hole-filled igneous rock that cooled quickly and had gas trapped inside of it when it cooled (thus creating holes). Photo by Jay Merrill.


Liked learning a little bit about igneous rocks? Stay tuned for my long read blog post at the end of the month outlining all types of rocks!

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