<p>Italy's Mount Etna provides a vivid image of one of the birthplaces of igneous rock during a night eruption. Igneous rock forms when magma cools and solidifies. (Lava is magma that has reached the Earth's surface.) Etna also shows off the etymology of igneous, from the Latin word for fire.</p>
Italy's Mount Etna provides a vivid image of one of the birthplaces of igneous rock during a night eruption. Igneous rock forms when magma cools and solidifies. (Lava is magma that has reached the Earth's surface.) Etna also shows off the etymology of igneous, from the Latin word for fire.
They form within the Earth and make up a large part of our planet.
• 2 min read
Rocks are so common that most of us take them for granted—cursing when we hit them with the garden hoe or taking advantage of them to drive in tent pegs on summer camping trips.
To geologists, a rock is a natural substance composed of solid crystals of different minerals that have been fused together into a solid lump.
The minerals may or may not have been formed at the same time. What matters is that natural processes glued them all together.
There are three basic types of rock: igneous, sedimentary, and metamorphic.
Extremely common in the Earth's crust, igneous rocks are volcanic and form from molten material. They include not only lava spewed from volcanoes, but also rocks like granite, which
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