Sand is one of the most abundant substances on earth. Sand consists of very small pieces of rock. If the sand grains are larger than two millimetres, it is called gravel.
Sand is formed over the course of many years from rocks that weather. Most sand is made of quartz, a mineral. Other sand comes from the rocks of volcanoes.
However, sand also comes from animals or plants. Mussels, for example, have a shell made of a substance that eggshells are also made of. Small pieces of shell or even the remains of coral often make up part of sand, especially on beaches or even in riverbeds.
There are different types of sand: the grains of desert sand are round and have a smooth surface. You can see this well under the microscope. When the wind blows them around, they grind against each other. The grains of sand from the sea, on the other hand, are angular and have a rough surface.
But sand is not only found in deserts, on coasts and on the seabed. There is a proportion of sand in every soil. If the earth contains a lot of sand, it is called a sandy soil. These are quite common in Europe.