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.
Each rock is made up of one or more different minerals. For example, granite. might be composed of the minerals quartz, orthoclase feldspar, mica, and hornblende. Limestone is an example of a rock that consists of only one kind of mineral: calcite. Although there are 2000 or more kinds of minerals in the earth, only about a dozen.