3. Minerals

   It is mineral every inorganic material body whose molecules have the same chemical composition. Minerals are classified according to their hardness on a scale of ten different degrees (Mohs scale): 1. talc, 2. gypsum, 3. calcite, 4. fluorite, 5. apatite, 6. orthoclase, 7. quartz, 8. topaz, 9.corundum and 10.diamond. In the upper picture, we see that the softest is the talc (1) and the hardest is the diamond (10).

   4. Indicates if these sentences are true or false:

    5. Rocks

        They are compact and hard minerals which we obtain stones and soil. They consist of various mineral components.

       Rocks are divided into three groups: igneous or volcanic, sedimentary and metamorphic.

        - Magmatic or volcanic rocks are formed by the cooling of magma (liquid inside the Earth) due to volcanic activity. In the upper left picture, we see a volcano and how magma comes out as lava. Examples: granite and pumice.

        - Sedimentary rocks come from materials resulting from the breakdown of other rocks. The materials are deposited in rivers, seas and valleys and form strata that acquire the rocky and compact structure due to the pressure and increased temperature. In the upper right picture, we see horizontal strata. Examples: clay, sand, limestone, gypsum, rock salt and coal.

    - The metamorphic rocks derived from sedimentary which are transformed by these factors: the high temperatures inside the Earth, the high pressures and the gaseous emanations from the magma. Examples: marble, slate and graphite.