Editing Magnetometer (section)

===Coal exploration===
While magnetometers can be used to help map basin shape at a regional scale, they are more commonly used to map hazards to coal mining, such as basaltic intrusions ([[dike (geology)|dykes]], [[sill (geology)|sills]], and [[volcanic plug]]) that destroy resources and are dangerous to longwall mining equipment. Magnetometers can also locate zones ignited by lightning and map [[siderite]] (an impurity in coal).

The best survey results are achieved on the ground in high-resolution surveys (with approximately 10&nbsp;m line spacing and 0.5 m station spacing). Bore-hole magnetometers using a Ferret{{clarify|What is a Ferret in this context and how is it used?|date=January 2023}}can also assist when coal seams are deep, by using multiple sills or looking beneath surface basalt flows.{{citation needed|date=June 2011}}

Modern surveys generally use magnetometers with [[Global Positioning System|GPS]] technology to automatically record the magnetic field and their location. The data set is then corrected with data from a second magnetometer (the base station) that is left stationary and records the change in the Earth's magnetic field during the survey.<ref>{{cite report |author=Abraham, Jared D. |display-authors=etal |date=April 2008 |title=Aeromagnetic Survey in Afghanistan: A Website for Distribution of Data |url=http://pubs.usgs.gov/of/2007/1247/html/afghan_dataproc.html |publisher=United States Geological Survey |docket=OF 07-1247 |access-date=25 August 2011 |archive-date=26 October 2011 |archive-url=https://web.archive.org/web/20111026023808/http://pubs.usgs.gov/of/2007/1247/html/afghan_dataproc.html |url-status=dead }}</ref>