Although we can not directly observe the core of the earth, there are instruments which can detect and record seismic wave vibrations on the ground and within the Earth which are generated by earthquakes and other plate movements. The energy released during an earthquake is measured in vibrating rocks by seismic instruments which record the intensity and type of vibration as wave patterns. Some waves appear to pass through solids, liquids or gases while other types of waves are stopped by liquid states. Based on data from such instruments, it is suggested that the outer portion of the core of the Earth is a liquid magma.

Other methods of obtaining information about minerals from the earth's core are derived from meteoric evidence, material found at the surface, drilling and gravity studies.