There are three types of rocks: igneous, sedimentary and metamorphic.
What is a mineral? What is a rock?
Here there is a brief introduction to what is a mineral:
The summary of the most important things in the unit is here.....
After reading the story of Timanfaya in your book, pages 62 and 63, have a look to the real images of the Island of Lanzarote where the Timanfaya volcano is.