Earth

Rocks

The 2000 known minerals can form an endless number of combinations and give life to an extremely high number of rocks. The processes that lead to the creation of a rock do not separate the different minerals the rock consists of. As a consequence, it is difficult to find rocks consisting of one single mineral. We will see that rocks are a mixture of different minerals; only those minerals that are present in a higher quantity identify the type of rock. For example granite is a magmatic rock that consists of many minerals, but especially quartz, feldspars and mica are always present in a large quantity. 

The process that leads to rock formation is fundamentally important, therefore rocks are classified according to how they were formed:
 

• magmatic or igneus rocks derive from the cooling of a mass of minerals in melted state (magma). Those minerals are mixed with gas substances during a process called magmatic process
• sedimentary rocks consist of rock fragments that have been accumulated during a process called sedimentary process
• metamorphic rocks are rocks that underwent modifications during geologic ages. The process that describes these changes is called metamorphic process.