Which approach analyzes chemical composition of rocks, soil, or sediment to guide mining?

• A. Geochemical testing
• B. Electromagnetic survey
• C. Open pit
• D. Shaft

Answer: (A)

Geochemical testing is the approach that uses the chemical makeup of rocks, soil, or sediments to guide mining. By collecting samples across an area and precisely measuring the concentrations of elements, explorers look for anomalies—areas where element levels are unusually high or low compared with the surrounding material. These chemical signals point to concentrations of ore minerals underground even when surface rocks look ordinary. Lab techniques such as XRF or ICP-MS quantify elements, while field methods like soil sampling, rock chip sampling, and stream sediment surveys are common ways to gather data. The idea is to map how chemical elements vary across the landscape and then drill into the most promising zones.

In contrast, an electromagnetic survey analyzes how the subsurface responds to electric and magnetic fields to reveal physical properties like conductivity or magnetism, not chemical composition. Open pit and shaft refer to mining methods or access strategies, not to how the subsurface chemistry is mapped.