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 ...

Obsidian, Rhyolite and Granite are all examples of igneous rocks. Metamorphic rocks are formed under the surface of the earth from the metamorphosis that occurs due to intense heat and pressure ...

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 ...

This lustrous rock can be found in nature, but it's easily accessible in stores. Intense, mysterious, and psychically potent, the Obsidian crystal captivates as much as it can perplex the curious ...

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