The first type, igneous, is a kind of rock that is formed when lava cools, so is the fastest forming type of rock, occurring on the surface of our planet after a volcano erupts, as well as under ...

Metamorphic rocks form from a previously existing rock, be it igneous, sedimentary or even an older metamorphic rock. Rocks turn metamorphic when they are subjected to very high heat and pressure.

Intrusive rocks cooled slower, allowing the minerals to form crystals that can be detected by the eye. The most common intrusive igneous rock in the area is known as diabase.

Igneous rocks are formed from molten material that cools and crystallizes below the Earth’s surface; dikes occur when this rock pushes its way into existing joint fractures.

Visual inspection of the dark gray rock suggested that it was probably a fine-grained basaltic igneous rock formed by the crystallization of magma near the planet's surface.

While many rocks don’t burn, some of them do. It depends on what the rocks are made of – and that’s related to how they were formed. There are three main rock types: igneous, sedimentary and ...

This strip of igneous rock was formed when hot magma pushed upward through the Earth's crust during the Jurassic Period, somewhere between 192 and 186 million years ago.

Scientists made the determination by examining igneous rocks and determining there was an increase in Earth's magnetic field between one to 1.5 billion years, corresponding with the time they ...

The scientists had thought the rock, formed roughly 3.5 billion years ago, might be sedimentary, formed as mud and sand deposited in a lakebed.

The researchers determined that it is likely igneous (formed by the solidification of magma) and, unlike any other igneous rocks previously found on Mars, has a mineral composition most similar to ...

Visual inspection of the dark gray rock suggested that it was probably a fine-grained basaltic igneous rock formed by the crystallization of magma near the planet’s surface.