In geology, mineralization is the process by which economically important metal deposits, ore bodies or veins are formed through various geological processes. Mineralization can occur in magmatic crystallisation, hydrothermal precipitation, metamorphic reaction, sedimentation and supergene enrichment, and its result is the concentration of elements originally dispersed in rocks to exploitable levels.
The first scientific study of the process was carried out by W. J. Henwood, Fellow of the Royal Society, in Cornwall and continued by R. W. Fox, also a Fellow of the Royal Society. Their observations of Cornish tin and copper veins laid the foundation for vein-genesis research and for systematic study of the relationship between mineralization and wall-rock alteration.
The term can also refer to the replacement of organic matter in dead organisms buried in sediment by water-borne minerals such as calcium carbonate (calcite), iron oxide (hematite or limonite) or silica (quartz). This mineralization is an important mode of fossilisation, in which hard parts or soft tissues are progressively replaced by minerals and may preserve morphology or even microstructure.
Mineralization can also mean the product of the process. For example, mineralization may introduce a metal such as iron into a rock, which can then be described as iron-mineralized. The intensity, type and spatial distribution of mineralization are central to mineral exploration and resource evaluation.
Mineralization can be divided by origin into magmatic, hydrothermal, sedimentary, metamorphic and supergene types. Magmatic mineralization is associated with crystallisation and differentiation of mafic and ultramafic magmas and forms chromite, platinum-group element and vanadium-titanium magnetite deposits. Hydrothermal mineralization forms veins of gold, silver, copper, lead, zinc, tungsten and tin as ore fluids precipitate along fractures. Sedimentary mineralization includes sandstone-hosted uranium, sedimentary phosphate, banded iron formation and evaporite salts. Metamorphic mineralization is associated with metamorphic fluids and structural focusing, and supergene mineralization forms through weathering, oxidation and secondary enrichment.
Mineralization can also be described by commodity and mineral assemblage, such as copper, gold, uranium, lead-zinc and rare-earth mineralization. Intensity is commonly measured by grade, tonnage and continuity of the ore body, and mineralization anomalies are geochemical or geophysical signals used in exploration to delineate prospective areas.
Mineralization is not the same as an ore deposit. Mineralization is the process or phenomenon of element enrichment, whereas an ore deposit is a mineralized body that meets economic extraction requirements. A region may have widespread mineralization without an economically viable deposit, or local high-grade mineralization may form a small deposit. Deposit evaluation considers grade, reserves, mining conditions, metallurgical performance, market price and environmental impact.
Mineralization is closely associated with wall-rock alteration. Hydrothermal mineralization is commonly accompanied by silicification, sericitisation, chloritisation, carbonatisation and kaolinisation, and alteration assemblages can indicate fluid temperature, pH and composition and serve as exploration guides. Mineralization is also structurally controlled, with faults, shear zones, folds and breccia pipes providing pathways and precipitation sites for ore fluids.
Mineralization research combines field mapping, petrography, mineralogy, geochemistry, isotopic dating and fluid-inclusion analysis. Ore mineral assemblages, alteration zoning, trace elements and isotopes can be used to infer metal sources, fluid evolution, precipitation mechanisms and timing. Remote sensing, geophysics and geochemical exploration are used to delineate anomalies and targets.
Modern research also uses the mineral-system concept, which treats source, fluid pathway, depositional site, preservation and later modification as an integrated whole. This framework helps predict mineralization at regional scale and supports deep and green exploration.
Mineralization can create resources but can also cause environmental problems. Acid rock drainage, heavy-metal release and radioactive element enrichment from natural mineralization may exist before mining, and mining and processing can accelerate these processes. Understanding natural mineralization backgrounds helps distinguish anthropogenic contamination from geological baselines and supports environmental management and remediation.