How are igneous rocks formed?

Even though geoligsts cannot actually see whats inside the earth, how did they know that the earth consists of layers?

What's the difference between magma and lava?

What are extrusive and intrusive rocks?

How do crystals form on igneous rocks?

What are minerals and their physical properties?

What are the other rock types?

What are the characteristics of igneous rocks?

How do geologists classify igneous rocks as extrusive or intrusive?

What does the texture tell us about igneous rocks?

What does colour tell us about igneous rocks?

Why do extrusive igneous rocks have very small crystals in them?

What's is the difference and similarities between Basalt and Obsidian?

What causes extrusive rocks to contain a large number of spaces in them?

What's the similarities between scoria and pumice?

Why do intrusive igneous rocks contain large crystals?

What are the three main minerals in granite?

What are some uses for Basalt and Dolerite?

What are some uses of Granite and
Scoria?

What are some uses of Pumice and Obsidian?