Question

Which one of the following minerals are formed by the decomposition of rocks, leaving a residual mass of weathered material?

• A. Coal
• B. Bauxite
• C. Gold
• D. Zinc

Answer 1

The correct option is B

Bauxite

Answer: The correct answer is option (b) – Bauxite

Bauxite

• Aluminium is obtained from Bauxite.
• India’s bauxite deposits are mainly found in the plateau region of Bilaspur-Katni, Maikal hills and Amarkantak plateau.
• Due to the decomposition of a wide variety of rocks rich in aluminium silicates, bauxite deposits are formed.
• Aluminium has great malleability, good conductivity. It is extremely light and combines the strength of iron.

Formation of Minerals

• Minerals are usually found in “ores”.
• An accumulation of any mineral mixed with other elements, is described with the help of the term ore.
• To make sure that extraction of minerals are economically viable, the mineral content of the ore must be in adequate concentration.
• The relative ease with which mineral ores may be mined is determined by the type of structure and formation in which they are found.
• This also helps in determining the cost of extraction.

Coal

• In India coal was mainly formed over 2 main geological ages. Some were formed about 55 million years ago are the tertiary deposits, some were formed during the Gondwana period, around 200 million years ago.
• West Bengal – Jharkhand (Damodar Valley) is the major source of Gondwana coal in India, these are metallurgical coal.
• Bokaro, Raniganj, Jharia are the important coalfields.
• Wardha, Son, Mahanadi and Godavari valleys are the other important locations for coal deposits in India.
• Nagaland, Arunachal Pradesh, Assam, Meghalaya are the North Eastern states where tertiary coals are located.