Ingredients of the Earth Crust
In our daily life, we use different kinds of materials and products that are made of tin, iron, copper, porcelain and others. We get all our necessary metals, nonmetals, metalloids and their compounds from earth, air or water. The part of air, water or earth from where we get all of these is called mine.
Minerals are found from the mines. Minerals may be solid like iron or copper mineral and liquid like petroleum or mineral oil. They may also be gaseous like natural gas.
Bangladesh abounds in natural gas which is used for cooking, the fuel of vehicles, power generation or as raw materials in various industries. Middle- Eastern countries have petroleum minerals and South Africa has mines of gold and diamond. So, different countries have different minerals which contribute to the development of that particular country as well as the whole world.
These solid, liquid and gaseous minerals are called mineral resources.
Points to remember:
- The substances available above and underneath the soil from which we get necessary metals and nonmetals to make various products are called minerals.
- The places where these minerals are found are called mines.
Position of Minerals
It was earlier idealized that minerals are only available beneath the surface but this concept is changed now. Some minerals are also available on the surface.
The sulfur mineral is available beneath the earth’s surface. The sand of Cox’s Bazar sea beach, Bangladesh contains zircon, the mineral of zirconium and hematite, the iron mineral, bauxite etc. are available on the surface of various places. Halogen minerals are available in the sea-water.
Different mineral substances get mixed up to make some hard particles which again combine together into a substance which is called rocks. On the basis of the way of their formation, rocks are of three types:
(i) Igneous rock (ii) Sedimentary rock and (iii) Metamorphic rock.
Igneous rock. Sedimentary rock and Metamorphic rock
(i) Igneous Rock
The molten mixture of different substances that pour out from the volcanoes is called magma. When magma cools down and solidiﬁes then it is called igneous rock. It is the source of many minerals.
(ii) Sedimentary Rock
As an effect of weather and climate, wind, rainfall, fog storms etc. clay and sands from the earth’s crust is washed or ﬂown away which is further gathered in some places as sediment. Then the different particles in that sediment organize themselves in layers and transform into a rock which is called sedimentary rock.
Example: sandy stone.
(iii) Metamorphic Rock
At various temperature and pressure, the igneous and sedimentary rocks transform into a new kind of rock which is called metamorphic rock.
Formation of different layers of subsurface rocks
Rocks are organized in different layers underground. Gravitation force, pressure, temperature and natural force etc. help to form different layers of rock underground.
Layers of rocks
The minerals from which metals and nonmetals can be extracted proﬁtably are called ores.
For example, galena (PbS) is the ore of lead as from it the metal lead is proﬁtably extracted. Iron can be extracted from pyrites (FeS2). Where aluminium cannot be proﬁtably extracted from bauxite. Hence, bauxite is called the mineral of aluminium but not the ore of aluminium.
Thus, we can say, all ores are minerals but not all minerals are ores.
*References- Wikipedia, NCTB Books