Key Points
Key Points: Minerals
- Rocks are made of minerals; some rocks, like limestone, have one mineral, but most contain many minerals in different proportions.
- Though over 2000 minerals are identified, only a few are common and form most rocks.
- The properties of minerals (colour, hardness, crystal form, lustre, density) depend on the physical and chemical conditions of their formation.
- Geographers study minerals for their distribution and economic use, while geologists study their formation, age, and composition.
- Minerals are classified as metallic and non-metallic; ores are minerals from which metals are extracted (e.g., bauxite → aluminium).
Key Points: Distribution of Minerals in India
- Coal → Jharia (Jharkhand) – largest coalfield in India.
- Iron ore → Singhbhum (Jharkhand).
- Oil (onshore) → Digboi (Assam) – oldest oilfield in India.
- Oil (offshore) → Mumbai High (Arabian Sea) – largest domestic oil source.
- Map marking rule → Minerals are shown by small dots on maps.
Key Points: Conventional Sources of Energy > Natural Gas
- Natural gas is a fossil fuel found along with petroleum and mainly consists of methane (about 95%).
- It is used in different forms such as LPG (cooking gas), CNG (vehicle fuel) and PNG (piped gas for homes).
- Mumbai High is the largest producer of natural gas in India; other producing areas include Assam, Gujarat, Andhra Pradesh, Rajasthan, Tripura and Tamil Nadu.
- Natural gas is a cleaner and eco-friendly fuel as it emits less carbon dioxide and leaves no solid residue.
- It is non-renewable, highly inflammable, and requires costly infrastructure for extraction, storage and transport.
