Geologic Survey with Magnetometer?

Projects General Guidance
1

For those that don't know, when mining companies are searching for Iron Ore deposits, they often use an Aerial Magnetic Survey, essentially looking for differences in the local magnetic field, generally a few 100 meters above ground level.

I would like to demonstrate this concept for a class. I'm thinking I could use, maybe square foot piece of steel, and as I move the magnetometer around the room it would read the change in the magnetic field. I understand that when calibrating the HMC5883l, you eliminate the "Hard Iron" sources and the "Soft Iron" sources. However I believe I would be trying to amplify the soft iron sources. Almost like a magnetic metal detector.

Does anyone have any insight on how I could use a magnetometer to demonstrate this process?

Thanks

2

An effective demonstration is to use the magnetometer as a compass, and watch the direction of "magnetic North" change as you bring magnetic materials near the sensor. You should be able to detect the influence of large steel plate from a few feet away.

For the magnetometer to work well as a compass, it must be calibrated. See this post: http://hobbylogs.me.pn/?p=17#more-17 or much better: Sailboat Instruments: Improved magnetometer calibration (Part 1)

3

about 30 years ago there was an article in EE magazine that did something similar.

A library search may find it.
It was pre internet so if available it will need a microfiche library search.