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Magnetic Properties Of Rocks And Minerals


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Metal detectors detect items that are conductive in nature or magnetic - or both. Ground mineralization and most hot rocks are related to the magnetic property or magnetic susceptibility. There are a few hot rocks that are so because they are conductive, graphite being a good example. Most however are due to differences in magnetic susceptibility, with magnetite and maghemite being stand out examples.

The source material for this chart is very technical http://www.alaska-gold.com/RF003p0189.pdf

The chart however is fairly simple - bigger numbers mean greater magnetic susceptibility and greater likelihood ground containing the mineral or rock will cause issues with metal detectors.

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This chart has "massive" information, massive being the key word here. In simple terms, these samples are of one mineral each, formed thru a cooling process that deposited "pure" minerals but did not form crystals, the exception being the sedimentary rocks.

In the real world we have a much more complex set of rocks to deal with, some rocks being made up of many different minerals, such as magnetite in quartz or garnet, pyrite, feldspar,magnetite in schist, for example.

Massive samples are easy to identify but the more complex rock structures take a bit more knowledge and testing to identify, sometimes being made up from several different minerals. Sometimes these mineral groupings can be seen with the human eye and sometimes a loupe is required.

So, if you beep a rock and want to know why it beeped, break the rock to expose a clean surface and have a look with a loupe. It may not be a massive sample, but, might be many different minerals.

Also, the listings should have been - sedimentary, metamorphic then igneous.

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Them there minerals and hot rocks aint got a chance--- got me a ferrite ring and S.S. offered to help me install the magic upgrade. Expect some  bragging and numerous big nugget photos soon.

 

  Found the entire report interesting.  Thanks Steve

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