Some ore deposits contain minerals that possess physical characteristics that can be measured by suitably sensitive instruments. Exploration based on the principles of physics is called geophysics. Exploration techniques utilize such physical properties as density, magnetic behavior, electrical conductivity, and radioactivity. Six basic geophysical exploration methods--gravity, seismic, magnetic, electromagnetic, electric, and radiometric-are commonly employed in the search for minerals.
Certain minerals distort the earth's magnetic field, and where sufficiently large concentrations of such minerals occur, variations can be measured by magnetometers mounted in aircraft, in ground vehicles, or positioned at stations on the ground. Magnetite iron ores have been found in many areas of the world using the airborne magnetometer.
In one case in the western United States, a very large iron deposit has recently been discovered beneath several hundred feet of barren volcanic flow rock erupted over the ore deposit. Magnetic copper skarn, magnetic nickel ore, and asbestos-bearing serpentine associated with certain magnetic intrusive rocks have been found, using the magnetometer. Some geophysicists propose the use of the magnetometer to detect gold placer deposits, because of their common association with black sands largely consisting of the mineral magnetite.
This passage comes from the Anatomy of a Mine web site produced by the United States Geological Survey (USGS).
1) A magnetometer tests which of these physical properties of a mineral?
2) How many basic geophysical exploration methods are commonly used to search for minerals?
3) According to this article, in order to search for ores, the magnetometer instrument can be used on which of these vehicles?
4) Which of these has NOT been found using a magnetometer?
Now, go to the ore deposit model that your teacher has set up in the classroom. Sketch the grid that you see on top of the file folder. Make sure you have the same number of squares as you see on the folder! Now use your magnetometer to find any ores that might be in this area. Put an "X" on squares where there seems to be a magnetic disturbance (if a disturbance seems to be in more than one square, do mark all of the squares in which you find the disturbance). Be sure to also mark in that square whether or not the disturbance was "north" or "south". Sketch: