2.2.5 Geophysical Surveys
In a geophysical survey, instruments are used to measure the physical properties of rocks such as their magnetism, electrical conductivity, density and radioactivity.
Several types of portable instruments may be used to take these measures. The data can be collected directly on foot or by flying over the land in a helicopter or airplane.
The data are then recorded on a map to detect any geophysically anomalous rocks.
 |
|
|
 |
Source | |
 |
||
A magnetic survey, for example, reveals rocks that contain magnetic minerals such as magnetite, pyrrhotite, chromite and ilmenite.
An electric or electromagnetic survey identifies rocks rich in conductive minerals such as chalcopyrite, pyrite, sphalerite and graphite.
 |
 |