Magnetic surveys are particularly useful for delineating ore bodies containing which minerals?

Magnetic surveys are particularly useful for delineating ore bodies containing which minerals?

• A. Quartz and calcite.
• B. Hematite and chalcopyrite.
• C. Gypsum and halite.
• D. Feldspar and mica.

Answer: (B)

Magnetic surveys work by detecting variations in the Earth’s magnetic field caused by minerals with magnetic or magnetizable properties in the subsurface. Ore bodies that contain iron-bearing minerals create noticeable magnetic contrasts against surrounding rocks, making them easier to delineate with a magnetometer. Hematite, an iron oxide, contributes to magnetic responses, and chalcopyrite—a copper-iron sulfide—is often found with iron-bearing minerals, enhancing the magnetic signature of the ore body. This combination provides a clearer anomaly that helps map the extent of the ore body. The other mineral groups listed are not known for producing strong magnetic anomalies in typical surveying conditions. Quartz, calcite, gypsum, halite, feldspar, and mica are largely non-magnetic or magnetically weak, so they don’t generate the pronounced magnetic contrasts that magnetics rely on.

Magnetic surveys work by detecting variations in the Earth’s magnetic field caused by minerals with magnetic or magnetizable properties in the subsurface. Ore bodies that contain iron-bearing minerals create noticeable magnetic contrasts against surrounding rocks, making them easier to delineate with a magnetometer. Hematite, an iron oxide, contributes to magnetic responses, and chalcopyrite—a copper-iron sulfide—is often found with iron-bearing minerals, enhancing the magnetic signature of the ore body. This combination provides a clearer anomaly that helps map the extent of the ore body.

The other mineral groups listed are not known for producing strong magnetic anomalies in typical surveying conditions. Quartz, calcite, gypsum, halite, feldspar, and mica are largely non-magnetic or magnetically weak, so they don’t generate the pronounced magnetic contrasts that magnetics rely on.