Gold Deposits
Definition & Formation
Gold deposits are concentrations of native gold or gold-bearing minerals formed through geological processes including hydrothermal activity, placer deposition, and erosion. They are classified into:
- Vein deposits (hard-rock)
- Placer deposits (alluvial/eluvial)
- Orogenic gold deposits
Key Geological Indicators
- Quartz veining
- Chloritization and silicification
- Presence of sulphide minerals (pyrite, arsenopyrite)
- Structural controls: faults, folds, and shear zones
Notable Global Regions
- Yilgarn Craton (Western Australia)
- Kalgoorlie-Super Pit
- Carlin Trend (Nevada, USA)
- Johannesburg Basin (South Africa)
Emerging & Hypothetical Deposits
- Suburban/Submerged Potential: Recent analysis suggests potential for undiscovered gold beneath urban and submerged areas due to historical river systems and sediment transport.
- See: Port Phillip Bay & Melbourne: Submerged and Buried Gold Potential Report
- Key points from OzGeology (2026):
- Geological parallels to offshore deposits suggest significant potential beneath Port Phillip Bay and Melbourne.
- Submerged and buried alluvial channels may contain residual gold concentrations.
- Exploration hindered by urban infrastructure but geologically plausible based on regional tectonic history.
Extraction Methods
- Open-pit mining
- Underground mining
- Heap leaching
- Carbon-in-pulp (CIP)
Economic & Environmental Impact
- Driver of colonial expansion (e.g., Gold Rushes)
- Environmental concerns: acid mine drainage, heavy metal contamination, land subsidence.