The magma itself is a horrifying soup of molten rock, dissolved gases (like water vapor and carbon dioxide), and crystals that haven’t melted yet. Imagine boiling a pot of spaghetti, but the spaghetti is solid rock and the boiling water is liquid fire. That’s magma. When it reaches the surface, we call it lava, but don’t be fooled—it’s still angry spaghetti.
And here’s a shocker: igneous rocks make up about 95% of the Earth’s upper crust. That means every time you walk on a sidewalk, you’re probably stepping on ancient, cooled-down lava. Your driveway? Basalt, an extrusive rock from Hawaiian volcanoes. Your granite counter? A billion-year-old magma chamber that went to sleep. You are literally living on a former planet-wide melting pot.
The Elemental Party: Silicon, Oxygen, and a Cast of Thousands
At the atomic level, igneous rocks are mostly oxygen and silicon. Yes, the same oxygen you breathe and the same silicon that runs your smartphone. In fact, about 74% of the Earth’s crust is oxygen and silicon, holding hands to form the mineral quartz. That means your computer chip and a mountain are distant cousins.
But don’t let the simple recipe fool you. Throw in some iron and magnesium, and you get dark, heavy rocks like basalt that form the ocean floor. Add a dash of aluminum and potassium, and you get light-colored, buoyant rocks like granite that make up continents. The difference between a mountain and a molehill? One extra mineral in the kitchen.
Igneous Rock Formation Chart
