Answer the following questions in about 150 words each. (a) Give an account of the geology and the process of formation of…

(a) Aluminium mineral deposits. India’s bauxite deposits are chiefly residual products of lateritization, in which aluminous rocks such as granites, gneisses, schists and volcanic rocks are subjected to prolonged tropical chemical weathering. Leaching removes silica, alkalis and ferric oxides, while aluminium concentrates as gibbsite, boehmite and diaspore in laterite crusts. Uplift, erosion and repeated weathering cycles control thickness and grade. The Eastern Ghats belt in Odisha, Jharkhand, Andhra Pradesh and Telangana hosts the largest lateritic bauxite occurrences; Gujarat and Madhya Pradesh contain important lateritic deposits. Karstic bauxite forms in limestone solution features where aluminous clays are enriched, especially in Jharkhand, whereas lateritic bauxite forms as a residual cap over crystalline rocks. Economic bauxite generally requires Al₂O₃ above 40 per cent and SiO₂ below 5 per cent, with low impurities, because silica raises alumina losses and caustic consumption in Bayer processing. These deposits underpin India’s aluminium industry and export earnings.

(b) Iron-titanium oxides in igneous rocks. Iron-titanium oxides are common accessory or dominant minerals in mafic and ultramafic igneous rocks, especially layered intrusions, ophiolites, basaltic cumulates and komatiites. The principal minerals are ilmenite (FeTiO₃), magnetite (Fe₃O₄), ulvöspinel (Fe₂TiO₄) and hematite (Fe₂O₃), with titanomagnetite forming a solid-solution series between ulvöspinel and magnetite; oxidation state, expressed as fO₂, controls the relative stability of magnetite, ilmenite and hematite. They commonly occur with chromite, olivine, pyroxene, plagioclase, apatite, zircon and platinum-group elements, and may carry vanadium, nickel and rare earths. Textures reveal their history: oxide cumulate layers, oikocrystic magnetite enclosing silicates, resorbed xenocrysts, brecciated oxide bands, and oxide-silicate reaction rims. On cooling, exsolution produces ilmenite lamellae in magnetite, and oxidation may develop hematite rims or lamellae. In India, such associations are important in the Eastern Ghats, Deccan traps and ophiolitic melange belts, where oxide minerals may indicate chromite, V-Ti and PGE potential. Such textures are used to infer magma evolution, oxidation conditions and ore-forming processes.

(c) Prospecting, exploration and sampling. Prospecting is the early, regional search for mineral targets using geological mapping, remote sensing, geophysics and reconnaissance geochemistry; it is broad, low-cost and risk-oriented. Exploration is the detailed, deposit-scale investigation that tests a target by trenching, drilling, geotechnical work and resource estimation, moving from inference to bankable confidence. In the UNFC classification, prospecting corresponds broadly to G4 reconnaissance, while exploration generally spans G3 to G1, with G1 representing detailed, mine-planning grade data. Sampling links field evidence to assay results. Chip samples are taken from exposed outcrops or trenches; channel samples follow a fixed width along a face; bulk samples represent larger volumes for metallurgical or grade tests; core samples from drill holes provide continuous stratigraphy and grade control. Good sampling requires systematic or random spacing, composite intervals, avoidance of bias, proper splitting, crushing, grinding and preparation for chemical or instrumental assay, with geostatistical methods used to estimate continuity and uncertainty.

(d) Cosmic abundance and Oddo-Harkins rule. The Universe is dominated by hydrogen and helium, from Big Bang nucleosynthesis, with heavier elements produced by stellar nucleosynthesis, supernovae and neutron-star mergers. By mass, hydrogen and helium exceed 98 per cent, while oxygen, carbon, neon, iron, nitrogen and silicon are the principal “metals”. Earth’s crust differs sharply: oxygen, silicon, aluminium, iron, calcium, sodium, potassium and magnesium dominate through silicate differentiation in continental crust. The Oddo-Harkins rule observes that elements with even atomic numbers are usually more abundant than their odd-numbered neighbours, because even-even nuclei, with paired protons and neutrons, generally have higher binding energy per nucleon and are more stable. It is not universal; hydrogen, an odd-Z element, is far more abundant than helium by mass. Typical examples include iron (Z=26) being more abundant than manganese (Z=25) and cobalt (Z=27), oxygen (Z=8) than nitrogen (Z=7) and fluorine (Z=9), and silicon (Z=14) than aluminium (Z=13) and phosphorus (Z=15).

(e) Earthquake hazards and mitigation. Earthquakes generate direct and secondary hazards. Ground shaking damages buildings, bridges and lifelines; liquefaction can cause soft ground to flow, toppling structures; surface rupture breaks land, pipelines and roads; co-seismic landslides and rockfalls block valleys and rivers; undersea earthquakes may generate tsunamis that inundate coasts. Secondary effects include fires from gas leaks, collapse of unsafe structures, disruption of water and sanitation, and disease. Mitigation must be multi-layered. Seismic hazard zoning and land-use planning keep critical facilities away from active faults, liquefiable soils and steep slopes. Building codes such as IS 1893, with local bylaws and competent design, ensure ductile, base-isolated or seismic-resistant construction; retrofitting of old schools, hospitals and industrial plants reduces vulnerability. Early warning, community preparedness, drills, emergency planning and insurance improve resilience. The National Disaster Management Authority and state authorities must enforce codes, monitor construction and integrate risk into planning, because mitigation is cheaper than reconstruction.