Geological Characteristics of Gold in the Central African Republic

Deposit Types

• Orogenic (lode) gold: Hosted in quartz veins and shear zones within Precambrian greenstone belts and metasedimentary sequences.
• Alluvial and eluvial deposits: Widely distributed in riverbeds, terraces, and floodplains, especially in the south-west (Mambéré, Lobaye, Sangha, Kadeï).
• Lateritic cover deposits: Gold concentrated in weathered regolith and lateritic soils above basement rocks.
• Hydrothermal systems: Associated with regional shear deformation and hydrothermal alteration in Neoproterozoic rocks.

Purity and Grades

• Gold from alluvial gravels is generally high purity (90–98%, 21–23 karats), reflecting natural mechanical concentration.
• Primary quartz veins can show grades from 2–5 g/t, though artisanal miners often target richer pockets.
• Limited modern exploration means grade variability is not fully constrained.

Associated Minerals

• Sulfides: pyrite, arsenopyrite, chalcopyrite occur in primary lode deposits.
• Heavy minerals in alluvials: magnetite, ilmenite, cassiterite, zircon often accompany placer gold.
• Trace platinum-group elements (PGE) have been reported in some alluvial sites.

Major Geological Zones

• Bandas Greenstone Belt: Hosts orogenic gold mineralization in quartz veins and altered schists.
• Dekoa Belt: Another greenstone-derived system with lode-type gold.
• Southwestern Rivers (Mambéré, Lobaye, Kadeï, Sangha): Rich in artisanal alluvial operations.
• Ndassima Mine (Ouaka region): The only known large-scale deposit, though geopolitically sensitive.

Exploration Potential

• The CAR shares geological continuity with West and Central African greenstone belts, yet remains largely under-explored.
• Potential exists for world-class orogenic deposits if systematically explored with modern methods.
• Alluvial zones suggest hidden primary sources that remain undiscovered.

Main Features (Summary Table)