Economic Geology and Mineral Resources
Economic Geology and Mineral Resources tests ore-forming processes, ore classification, grade and tonnage, and the distribution of Karnataka's mineral deposits. Expect questions on reserves versus resources, gangue, and specific local deposits.
Core rules
- An ore is a rock from which a mineral or metal can be extracted economically; gangue is the unwanted material.
- Magmatic, hydrothermal, sedimentary, residual and metamorphic processes concentrate ore minerals.
- Grade is the concentration of the valuable element; tonnage is the amount of ore.
- A reserve is economically mineable; a resource is potentially available but not necessarily economic.
- Karnataka's key deposits include Hutti gold (Raichur), Bellary–Hospet iron ore, Sandur manganese, Nuggihalli chromite and lateritic bauxite.
Worked example
A deposit contains 2 million tonnes of ore grading 1.5% copper. Calculate the contained copper. Reasoning: contained metal = ore tonnage × grade = 2,000,000 t × 0.015 = 30,000 t Cu. This is contained metal, not recoverable metal; recovery and dilution would reduce the saleable amount.
Traps
- Do not treat resources and reserves as identical.
- Convert percentages correctly: 1.5% = 0.015, not 0.15.
- A high-grade deposit may still be uneconomic if recovery or transport costs are high.
- Kolar Gold Fields ceased underground operations in 2001; Hutti remains an active gold mine.
Karnataka link
Bellary–Hospet haematite ores and Kudremukh magnetite are major iron resources; Sandur is known for manganese; Nuggihalli for chromite.