Economic Geology and Mineral Resources
What the exam tests
Economic Geology and Mineral Resources covers ore-forming processes, identification of ore minerals, and the distribution and uses of Kerala's mineral resources.
Core rules
- Ore minerals: oxides (hematite Fe₂O₃, magnetite Fe₃O₄, bauxite, chromite), sulphides (galena PbS, sphalerite ZnS, chalcopyrite CuFeS₂, pyrite FeS₂), carbonates such as siderite, and native gold.
- Deposit types: magmatic segregation (chromite), hydrothermal veins (gold–quartz), residual lateritic (bauxite), placer (beach and stream sands), sedimentary (coal, limestone).
- Kerala: ilmenite, rutile, zircon, monazite and sillimanite in the Chavara–Neendakara heavy-mineral sands; bauxite from laterite in Kasaragod and Kannur; kaolin (china clay) in Kollam district; limestone from Quilon beds; graphite in southern khondalites.
- Gangue is the waste mineral; grade is the concentration of the valuable element; a reserve must be economically extractable.
Worked example
An ore body of 500 tonnes contains 0.6% monazite. Mass of monazite = 500 × 0.006 = 3 tonnes. If the cut-off grade were 1%, the same body would not be classed as ore at all - grade, not total mass, decides ore status.
Traps
Treating every mineral occurrence as ore. Confusing reserves with resources. Naming monazite without stating the element it is worked for (thorium, with rare earths). Describing beach sand as a rock rather than a placer concentration.