Marble. Chalk. The Giant’s Causeway. All made of rock but all different. Learn all about the three different types of rock found on Earth with BBC Bitesize.

Obsidian is formed, in particular, by explosive volcanoes, not the tranquil types found in Hawaii. Its essential ingredient is the thick, gooey molten rock, or magma, that lies below these ...

As with other forms of obsidian, rainbow obsidian is both rock and glass. However, this isn’t the same kind of glass that’s used in your nice new French doors. It’s far more badass, because ...

Rocks turn metamorphic when they are subjected to very high heat and pressure. This alters the chemical and structural makeup of the minerals within the rock, changing it into a new metamorphic rock.

Archaeologists use obsidian to determine how far people traveled on ancient trade routes across Wyoming. Each obsidian flake ...

Cutting edge Obsidian – a type of volcanic glass – can produce cutting edges many times finer than even the best steel scalpels.