Understanding Copper Oxides & Sulfides

• Hayden Locke, CEO of Marimaca Copper, demystifies copper oxides and sulphides.
• Copper mineralization for deposits starts as primary sulfide mineralization. Over time, exposure to surface water and air turns some of these minerals into oxides.
• Oxides can often be dissolved in weak acid, making copper recovery efficient. Sulfides, on the other hand, don't leach, so they require a different process.
• Oxides ultimately produce a high-grade copper cathode, while sulfides result in a concentrate which needs further processing at smelters.
• Oxide projects generally have lower capital costs, allowing for potentially smaller scale operations. However, recovery rates and ore grade can affect profitability. The capital intensity for sulfide projects tends to be higher.
• Sulfide projects often come with by-product credits like gold or silver. While it's possible to extract these from oxide deposits, it typically requires a secondary leaching process and is less common.

Copper deposits come in two main types - oxides found near the surface and sulfides found deeper underground. While both contain copper, their geological origins and extraction methods differ significantly. Understanding these differences is key for investors evaluating copper mining projects.

Understanding Oxides

Copper oxides form when sulfide minerals are exposed to oxygen and water. This weathering process enriches copper content compared to the original sulfide deposit. Oxides are typically found within a few hundred meters of the surface, but can run deeper along fractures and faults that allow oxidizing water to penetrate.

The copper in oxides is soluble, allowing direct extraction through leaching rather than physical separation. Oxide projects require less grinding, simpler processing, and lower capex compared to sulfides. However, they lack potentially valuable by-product credits like gold and silver. Global copper supply is dominated by sulfides, but standalone oxide projects can be attractive at smaller scales.

Sulfide Copper Characteristics

Sulfide extraction is more complex, requiring physical separation via froth flotation after fine grinding. This produces a copper concentrate rather than pure cathode copper. Smelting and refining are then needed to upgrade into finished copper metal, adding costs. But sulfides provide credits from by-product metals which can significantly improve project economics.

Key Factors for Investors

For investors, oxide projects offer faster payback and lower risk due to simpler metallurgy and processing. But sulfide projects provide greater scale, resources, and metal diversification. Recent technological advances may allow economic recovery of copper from low-grade sulfide deposits, though oxides will remain the cheaper option for smaller projects.

Understanding where in the weathering profile a copper deposit lies is critical. Oxide caps can mean early cash flow, allowing projects to self-fund sulfide development underneath. But deep sulfide-only deposits require patient capital and strong technical expertise. Geology, mineralogy, metallurgy, processing plans, and resulting economics can differ radically between oxides and sulfides.

Key factors investors should examine include:

• Ore types - ratio of oxides vs sulfides, with detailed mineralogy. Enriched oxides are ideal for early operations.
• Processing plans - acid heap leaching for oxides vs grinding and flotation for sulfides. Capex and opex differ considerably.
• Recoveries - typically 70-85% for oxides using leaching, over 90% for sulfides via flotation/concentrate.
• Scale - oxides sufficient for standalone projects at ~50,000 tonnes copper p.a. Sulfides need large scale to be economic.
• Infrastructure - oxides can be processed on site, sulfides often require concentrator, smelter, transport.
• By-products - sulfides provide credits from gold, silver, molybdenum etc. Oxides are often just copper.
• Geo-metallurgy - changes in mineralogy with depth can significantly impact project plans and economics.

With copper fundamentals strong, both oxide and sulfide projects have potential. But investors need to dig into the details to properly evaluate opportunities. Geology and mineral processing drive key project metrics and financial outcomes. While copper is copper, not all deposits are created equal. Understanding the critical technical differences between oxides and sulfides allows properly assessing project risks and upside.

Conclusion

Copper presents opportunities for investors, with demand projected to grow on the back of green energy and electrification trends. Both oxide and sulfide deposits have roles to play. While sulfide operations drive global production thanks to scale and by-product credits, nimble oxide projects can offer faster returns on investment. By diving into the technical details and grasping key geological differences, investors can cut through the hype and accurately evaluate risks and upside. Understanding copper mineralogy provides the clearest lens for separating promising ventures from risky speculations. While copper's future shines bright, investors must approach projects with eyes wide open.

About Marimaca Copper

Marimaca Copper is a TSX-listed company with an exciting copper discovery - the Marimaca Copper Project in Chile's Antofagasta region. This is the only major new copper discovery globally in the past 5 years and is considered low risk with significant exploration potential. Marimaca's vision is to create value for shareholders by realizing the full potential of Marimaca, which could become one of the most significant recent copper-oxide discoveries, as well as exploring for other large-scale deposits in the region. The Marimaca deposit challenges accepted exploration wisdom as an intrusive-hosted system unlike the typical volcanic-hosted deposits nearby. Its prime coastal location near excellent infrastructure enables potentially low-cost development. As one of the most important new copper projects in Chile in the past decade, Marimaca is a high profile development opportunity in a country with limited new copper exploration success.