Minerals

Minerals have an important place in human evolution and expansion of civilizations. People primitive stone age flint tools used. With about 10 000 years ago, they learned the technique of extraction of copper from its natural minerals, and invented bronze, an alloy of copper and tin, which marked the starting of the Bronze Age. Since the early Iron Age, with 3 300 years ago, people have found more and more ways to use the materials found in the earth's crust, and modern industry continue to depend on the exploitation of mineral wealth of the earth.

It is important to know what they are, how they form and how to distinguish them when looking for new reservoirs. Scientists have identified about 3 000 minerals, of which only 100 are common. Minerals are defined as inorganic . They are usually solid, except for mercury, which is mercury in its natural state and is liquid.

Two elements, oxygen and silicon, representing 74% of the mass of the earth crust. Another six elements  are another 24, 27%. Taken together, these eight elements represent almost 99% of the earth's crust.

The most common minerals are silicates, silicon and oxygen chemical combinations, and often containing one or more of the other six common elements. Slicatii common include quartz, feldspar called micelles and group, all three, in different proportions, the main components of various types of granite. Quartz formed by erosion of granite, often accumulates on the coast and is the main constituent of sandy beaches.

Common minerals such as feldspars, quartz and mica are minerals that form rocks. This distinguishes them from minerals which occur in small amounts. Calcutta, mineral-forming limestone, is another important mineral composed of eruptive rock.

Because there are so many minerals in their natural state, mineralogy had to establish a systematic approach to identifying, based on the differences between physical and chemical properties of each mineral. The properties studied can be simple, such as color and durittea until the properties are complicated chemical analyzes.

Some minerals, such as azurite (blue) and malachite (green) can be identified based on color. But color can often introduce in error because many minerals can occur in varied colors. These variations may be due to dirt, heat, light, irradiation and wear.

The scratches of a mineral powder is produced. Sometimes the color that differs from that of the mineral powders. For example, black powder mineral hematite is red, while magnesium powder, which is similar to hematite is black.

Hardness is another method of differentiation of minerals. Minerals are ordered on the Mohs scale from 1 to 10. Talc, a soft mineral, is on position 1 on this scale, while the diamond, the hardest natural Sustiva, ranked 10.

Other minerals such as chromite  foartze quickly separates and settles at the base of the magma. There they form deposits called igneous separations.

The liquid that remains is becoming increasingly concentrated. A parete he creeps into the cracks of new rocks, forming large crystals, called petmatice deposits. Another part is stored in crevices of rocks located in the immediate vicinity. Finally, riman only liquids generically called hidroternmale solutions. These solutions often rich in rare elements can move fairly large distances before forms deposits in cavities and fissures, called veins and valves.

Other mineral deposits are formed by the action of rivers, seas and winds that erode and indepartreaza soft rock fragments such as sand or clay rocks. In such heavy ore deposits often become concentrated and compressed into hard rocks such as sandstone.

Iron is sometimes stored in rocks underwater formnd so-called iron ore. In the tropics occurs UZN different kind of chemical action caused by heavy rains that action delete rocks containing aluminum silicates. Silicates are removed, creating rich ore bauxite (aluminum ore). Rainwater Alste acid dissolve metals in rocks VCAR are redeposited at a greater depth.

Exploitation of metal deposits is fpacea randomly once. Today is utilizeazpa scientific methods. Geological map shows the most attractive zonwele determined ajurtorul often with pictures taken from aircraft or satellites. Geologists interptreteza these maps and photographs, learning about rocks and valuable information about their structures.