Mineral : A homogenous, naturally occurring substance with a definable internal structure.
- They are found in varied forms in nature.
- Rocks are combinations of minerals.
- A particular mineral that formed from a certain combination of elements depends upon the physical and chemical conditions under which the material forms
- Because of this different minerals have different colour, hardness, crystal forms, lustre and density
Importance of minerals
- They are indispensable part of our lives.
- Life processes can’t occur without minerals.
- The food we eat contains minerals.
- Cars, buses are manufactured from minerals.
- The process of taking out minerals from rocks buried under the earth’s surface is called mining.
- Minerals that lie at shallow depths are taken out by removing the surface layer; this is known as open-cast mining.
- Deep bores, called shafts, have to be made to reach mineral deposits that lie at great depths. This is called shaft mining.
- Petroleum and natural gas occur far below the earth’s surface. Deep wells are bored to take them out, this is called drilling
- Minerals that lie near the surface are simply dug out, by the process known as quarrying.
Mode of Occurrence of Minerals
- In igneous and metamorphic rocks : The smaller occurrences are called veins and the larger occurrences are called lodes. Examples: tin, copper, zinc, lead, etc.
- In sedimentary rocks: In these rocks, minerals occur in beds or layers. Coal, iron ore, gypsum, potash salt and sodium salt are the minerals found in sedimentary rocks.
- By decomposition of surface rocks: Decomposition of surface rocks and removal of soluble constituents leaves a residual mass of weathered material which contains ores. Bauxite is formed in this way.
- As alluvial deposits: These minerals are found in sands of valley floors and the base of hills. These deposits are called placer deposits. Examples; gold, silver, tin, platinum, etc.
- In ocean water: Most of the minerals in ocean water are too widely diffused to be of economic importance.
- But common salt, magnesium and bromine are mainly derived from ocean waters
(i)Iron ore –
– Backbone of industrial development.
– Magnetite is the finest ore & has 70% iron.
– Hematite ore has 50 -60 % iron content .
– Limonite ore has 40 -60 % iron content .
– Siderite ore has 40 -50 % iron content
Production of iron ore showing state wise share
(ii) Manganese –
– Used in manufacturing of steel & ferro
-manganese alloy , bleaching powder , insectides & paints .
– 10 kg manganese required to manufactured 1 tone of steel .
– Largest producer – Orissa .
Production of manganese showing state wise share
Non – ferrous minerals
(i) Copper –
– Production of cu is critically deficient in India .
– Cu is malleable , ductile & a good conductor .
– Used in electrical cables & chemical industries .
– Malghat mines in MP produce 52% of copper .
– Khetri mines in Rajasthan is also famous for cu production .
(ii) Bauxite –
– It is a clay like substance .
– Bauxite deposits formed by decomposition of rocks rich in aluminium silicates .
– Aluminium combines the strength of metals with extreme lightness & with good conductivity & malleability.
– Largest producer – Orissa (45%)
Production of copper & bauxite
– Made up of a series of plates or leaves.
-It can be clear, black ,green or brown.
– Mica deposits r found in the northern edge of Chota nagpur plateau.
-Koderma Gaya – Hazaribagh belt of Jharkhand is the leading producer
– Found in association with rocks composed of calcium carbonates or calcium & magnesium carbonates.
– Found in sedimentary rocks.
-Raw material for cement industry.
– Essential for smelting iron ore in the blast furnace.
Production of limestone
Read the Second part of the lesson here.