How are Igneous Rocks Made?
Igneous rocks are made from melted rock, which is called magma. Rock can get hot enough to melt into magma during a volcano eruption, but it can also cool underground. The more slowly the magma cools the bigger the crystals inside the rock will be.
What Kinds of Rock are Igneous?
- Granite: A hard igneous rock made of large crystals. Granite is used for things like the fronts of buildings, gravestones and worktops because it can be polished into a shiny, smooth surface.
How are Metamorphic Rocks Made?
Like sedimentary rocks, metamorphic rocks are formed from other rocks. These can be sedimentary or igneous. Rocks become metamorphic when they change due to heat or pressure. This can happen when the earth moves or when they are close to magma. Chemical changes then take place, forming metamorphic rocks.
The crystals in metamorphic rocks are layered, which means that they can easily be split apart.
What Kinds of Rock are Metamorphic?
- Slate is made from shale, which changes underground. It is water-resistant and splits in flat layers. Slate is a good material for roof times or surfaces that need to be very flat, like writing slates or snooker tables.
- Marble is formed out of limestone. It is a hard crystalline rock and has many uses, from building to sculpture. Marble can even be ground down and used in soaps and cleaning products.