Earth Science: Rocks
Humans have mined rocks and minerals since the Stone Age, using them as raw materials. Gems are frequently used for jewelry because of their form, color, and luster.
The study of the origin, characteristics, and composition of rocks is known as petrology, while mineralogy studies the origin, characteristics, and composition of minerals.
Minerals – Formation
Minerals, including metals and salts, are the solid building materials of the Earth. Minerals develop through an array of geological processes, such as sedimentation, volcanic eruptions, or chemical weathering.
Minerals are solid matter with a crystal line structure. They consist of both pure elements and chemical compounds, and are classified according to the way they were formed. The different types of formation classifications include igneous, sedimentary, metamorphic, and weathered minerals. Some minerals, such as garnet, can have multiple classifications because they can be formed in multiple ways.
Igneous minerals
Igneous minerals are formed when magma from the Earth’s mantle cools at a temperature of 2732T (1500°C), causing crystallization of the molten rock to the extent that no new minerals can emerge.
Examples of igneous materials include feldspar, quartz, and mica.
Sedimentary minerals
Many minerals are formed by sedimentation. Sedimentation can occur by evaporation, compression, and chemical reaction. Sedimentation by evaporation occurs when seawater evaporates and leaves minerals such as calcite, dolomite, anhydrite, gypsum, halite (rock salt), and potassium chloride.
Clay is formed by the compression of loose particles by increased temperature and pressure, along with chemical reactions. Sedimentary rocks cover nearly 75 percent of the Earth’s surface.
Metamorphic minerals
Metamorphic minerals are the result of changes in the original crystal lattice of other minerals. When high temperature 01 intense pressure is present, the original crystal lattice of minerals becomes unstable and the components will take the form of other structures to withstand the adverse conditions.
The group of metamorphic minerals includes graphite, talc, and garnet.
Weathered minerals
Weathered minerals are formed by changes in the chemical composition of minerals due to outside conditions.
Copper ores, when exposed to the air, oxidize and form malachite. Kaolinite is formed when clay is subjected to chemical decomposition above ground.