A dodo egg is a renewable food item that is randomly left behind by a dodo bird. Dodo eggs are large and oval in appearance with a light blue shell with a wavy pattern or darker areas.
As a result, rocks form quickly and mineral crystals are very small. Rhyolite is one type of rock that is formed when lava cools. It contains similar minerals to granite. However, as you can see in Figure 3.21, the mineral crystals are much smaller than the crystals in the granite shown in Figure 3.20.
Such rocks are known as ores and the residue of the rock after the mineral has been extracted is called tailing. The classification of rocks also depends on their mineral and chemical composition, texture and the process of formation. Rocks are therefore classified as igneous, sedimentary and metamorphic. A rock cycle defines how one rock form changes to another.