Cliffs made of magnetite are naturally magnetic and can cause compass needles to spin wildly.

Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe3O4. It is the most magnetic of all the naturally occurring minerals on Earth. When magma containing magnetite cools, the mineral grains align themselves with the Earth's magnetic field before the rock solidifies. This process, known as thermoremanent magnetization, effectively freezes a record of the magnetic field in time.Naturally magnetized pieces of magnetite are called lodestones. These were used by ancient civilizations, such as the Greeks and Chinese, to create the first compasses. In places like the Magnet Mountain in the Ural Mountains of Russia or the Iron Mountain in Missouri, the concentration of this mineral is high enough to significantly deflect modern magnetic compasses. This phenomenon is known as a local magnetic anomaly.Geologists use these magnetic rocks to study paleomagnetism, which provides evidence for plate tectonics. By analyzing the orientation of the magnetic minerals, researchers can determine where a landmass was located relative to the magnetic poles millions of years ago. For instance, studies of the Deccan Traps in India have used magnetite alignment to track the subcontinent's 50-million-year journey across the Indian Ocean.The strength of the magnetic field in these cliffs can vary based on the purity of the magnetite and the intensity of the Earth's field at the time of cooling. While modern GPS navigation is unaffected by these minerals, traditional maritime and aviation magnetic compasses still require 'deviation' corrections when traveling near large ore deposits. This ensures that the magnetic pull of the earth's crust does not lead the vessel into dangerous waters.