Due to goldfields being highly mineralized, it can be challenging to find what you’re looking for when you’re out hunting for gold-nuggets or other precious metals. Those fields can contain lots of conductive junk and rocks that are often less valuable.
While most people overlook the conductivity of minerals when they’re out in the field, there are some rocks and minerals that conduct at least some electricity. Because of this, your metal detector is likely to pick up on these as well. But what rocks and minerals exactly will set off your metal detector?
Let’s go through a few of them so you can identify them on your next trip.
Manmade rocks
Unfortunately, not everything you find will be a winner. You may actually come across a great deal of trash while you’re out hunting. That trash will sometimes come in the form of manmade rocks, of which there are many, so it is best to know what you’re looking at when you’re looking at it.
Slag
These are man-made metallic by-products that come from metal smelting that has oxidized over time. They’re often encased with surrounding rock and usually look similar to meteorites as they appear melted on the surface. Slags contain high iron content, meaning they stick to a magnet and will register on a metal detector.
Human-made conglomerate
These are the result of man-made metal items like nails and cans that have been disposed of into water and have corroded over time. They attract surrounding objects and other minerals to form a conglomerate. They are most often found on beaches or by bodies of water and since they are made up of metal oxides, your detector will absolutely pick them up.
Natural/Native metals
Natural metals include ore-bearing rocks, which are metals that are naturally formed and held inside of rocks. These may also be native metals, which exist in their pure, metallic form in nature, such as gold, platinum, aluminum, copper, and lead.
Michigan copper float is made up of copper sediments that were deposited as a result of glacial movements. This type of copper is easily identifiable by its bright green crust color, high density, and malleability. Due to copper being highly-conductive, Michigan copper float will easily set off your metal detector.
Hot Rocks
These are rocks that contain iron-bearing minerals. These minerals can include iron oxides like magnetite, maghemite, hematite, lepidocrocite, and limonite. There are two types of hot rock you’ll most commonly get a reading on from your metal detector, such as:
Negative Hot Rock
A negative hot rock is typically magnetite or often contains magnetite. They are usually dark or black in color, and in some cases, will have rust stains. They’ll be identified easily as they are pretty heavy and a magnet can attract them easily.
When your metal detector identifies a negative hot rock it will produce a “boing” sound. The detector tends to respond more as you move it away from the negative hot rock instead of when hovered directly over it. Unlike the sharp “zip” sound of a metal target, the sound of negative hot rocks is quite distinctive.
Positive Hot Rock
These are the second type you’ll find most commonly and are highly mineralized rocks, small, and mostly found right on the surface. Usually, they’ll have a reddish coloring to them, but can also be yellow or brown.
They are the most challenging to deal with since they give off a sharp sound just like that of a gold nugget or other metal targets. As such, it can be pretty frustrating when you’re hunting in a highly mineralized field as it’s hard to differentiate between positive hot rocks and valuable metals.
Meteorites
The most common types of meteorites that you’ll encounter include stony, iron, and stony-iron. All three varieties contain a substantial amount of iron and nickel minerals. This makes them easily attracted to a magnet and detectable by a metal detector.
Conclusion
While it can be a bit frustrating to encounter other materials while you’re trying to find gold or more valuable metals, there’s no need to despair. Most detectors have helpful identification features that will help you sort through what might not be worth your while. Regardless, any time you spend hunting is time spent doing what you love.
With the right detector and enough experience, you’ll be able to differentiate between these other rocks and minerals and what you’re looking for.
