Mineralogy & Petrology
Petrology essays require understanding rock-forming processes quantitatively: igneous petrology (Bowen's reaction series; fractional crystallisation; melt generation — solidus and liquidus; MORB vs OIB vs arc magma geochemistry — spider diagrams normalised to primitive mantle); metamorphic petrology (P-T paths; metamorphic facies — zeolite, greenschist, amphibolite, granulite, eclogite; isograds; index minerals — chlorite, biotite, garnet, kyanite, sillimanite in pelitic metasediments); sedimentary petrology (diagenesis — compaction, cementation, dissolution; QFL ternary diagrams for provenance analysis; porosity and permeability for reservoir characterisation). Students frequently confuse rock types, misidentify minerals from thin section descriptions, or fail to apply phase diagrams correctly.