Like other igneous rocks, the glossy glass originates from ... It appears as a dark glassy rock that’s typically black, although it can take on hues of green, brown, and other colors due to ...

Obsidian is perhaps best known in its role as the dark black blade atop ancient spears ... origin is what classes rainbow obsidian as an igneous rock. Lava destined to become obsidian cools ...

Igneous intrusions are a type of rock feature. They form when molten rock cools below the surface of the Earth. Join Isla and Connor as they explore igneous rock landscape features at Traprain Law ...