WHERE DO THESE METALS COME FROM?
Introduction
Haban comes to Guwahati with his father from a remote village. He sees people getting into a strange house like objects which move along the road. He also sees a “kitchen” dragging a number of houses along with it. He is amazed and asked his father “Why don’t our houses move like the one we saw in Guwahati, Ba?” Ba replies, “These are not houses, they are buses and trains. Unlike our houses these are not made of bricks and stones, metal like iron and alluminium are used in making these. They do not move on their own. They are driven by an engine which needs the energy to work.”
We use different things in our daily life made from metal. Can you list a number of items used in your house made of metals? Where do these metals come from?
You have studied that the earth’s crust is made up of different minerals embedded in the rocks. Various metals are extracted from these minerals after proper refinement.
Minerals are an indispensable part of our lives. Almost everything we use, from a tiny pin to a towering building or a big ship, all are made from minerals. The railway lines and the tarmac (paving) of the roads, our implements and machinery too are made from minerals. Cars, buses, trains, aeroplanes are manufactured from minerals and run on power resources derived from the earth. Even the food that we eat contains minerals. In all stages of development, human beings have used minerals for their livelihood, decoration, festivities, religious and ceremonial rites.
A bright smile from toothpaste and minerals
Toothpaste cleans your teeth. Abrasive minerals like silica, limestone, aluminium oxide and various phosphate minerals do the cleaning. Fluoride which is used to reduce cavities comes from the mineral fluorite. Most toothpastes are made white with titanium oxide, which comes from minerals called rutile, ilmenite and anatase. The sparkle in some toothpaste comes from mica. The toothbrush and tube containing the paste are made of plastics from petroleum. Find out where these minerals are found?
All living things need minerals
Life processes cannot occur without minerals. Although our mineral intake represents only about 0.3 percent of our total intake of nutrients, they are so potent and so important that without them we would not be able to utilise the other 99.7 percent of foodstuffs.
Activity:
1. Dig a little deeper and find out how many minerals are used to make a light bulb?
2. Dig a little deeper and collect “Nutritional Facts” printed on food labels.
Source: This topic is taken from NCERT TEXTBOOK
WHAT IS A MINERAL?
Geologists define a mineral as a “homogenous, naturally occurring substance with a definable internal structure.” Minerals are found in varied forms in nature, ranging from the hardest diamond to the softest talc. Why are they so varied?
You have already learnt about the rocks. Rocks are combinations of homogenous substances called minerals. Some rocks, for instance, limestone, consisting of a single mineral only, but the majority of the rock consists of several minerals in varying proportions. Although over 2000 minerals have been identified, only a few are abundantly found in most of the rocks.
A particular mineral that will be formed from a certain combination of elements depends upon the physical and chemical conditions under which the material forms. This, in turn, results in a wide range of colours, hardness, crystal forms, lustre and density that a particular mineral possesses. Geologists use these properties to classify minerals.
Study of Minerals by Geographers and Geologists
Geographers study minerals as part of the earth’s crust for a better understanding of landforms. The distribution of mineral resources and associated economic activities are of interest to geographers. A geologist, however, is interested in the formation of minerals, their age and physical and chemical composition
Source: This topic is taken from NCERT TEXTBOOK