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"Hot Rocks"
Can Be A Major Problem For Some People Using A Metal
Detector, And Cool Collectables To Others.
Metal Detectors Respond To The
Presences of A Magnetic Field. Natural
Occurring Magnetic Minerals Can Cause Problems For
Anyone Using A Metal Detector. Rocks Can, And
Are, Dug Up By Metal Detector Users. Most Of
These Rocks Can Be Avoided With The Proper Use Of A
Quality Metal Detector Designed To Avoid
These Minerals Properly.
From A Different Point Of View, A High-Performance
Metal Detector, Properly Designed For Detecting In
Highly Mineralized Environments, Offer
Circuitry-Detection-Control To The Point That Offers
A Mineral Collector, Rock Hound, Meteorite
Collector, Gold Nugget Prospector, Copper Nugget
Prospector, Silver Nugget Prospector, etc.., The
Perfect Machine To Detect Such Targeted Treasures.
Mineralized Rocks
/ "Hot Rocks"
Casanova's Reference Material "Hot Rock" is
a
coined phrase given to mineralized rocks, by the metal
detecting industry, that causes a metal detector to
respond.
Mineralized
rocks can be detected by a metal detector because they
are different in magnetism than the
surrounding body of ground contents.
Negative - Hot Rocks
Such as
Magnetite, tend to give a "booing" sound when the
searchcoil is passed over them. The greater the
difference between the rock and the surrounding
ground, the louder the "booing" detection sound from a
metal detector. An Iron Oxide.
Positive +
Hot Rocks
Such as
Maghemite, tend to sound just like any other metal
target. Positive hot rocks can give the same detection
sound as a nugget and can give a "zip-zip" sound.
Positive hot rocks will test any prospectors patience.
An Iron Oxide. Commonly used in
magnetic tape, for example in the magnetic layer of
audio tape, floppy disk, digital tape, etc.. The
particles can be magnetized to represent data.
Magnetic Minerals
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Magnetism occurs
when there is an imbalance in the structural
arrangement of iron ions. Iron is found in two
principle ionic states; called ferrous and ferric
ions. The ferrous ion has a charge of positive-two;
the ferric ion has a charge of positive-three. The two
ions have different atomic radii. The higher-charge of
the ferric-ions pulls the electrons surrounding the
ion in tighter, making for a smaller radii. This fact
can lead to the different ions being placed in
separate positions in a crystal structure. Electrons
that move from the ferrous to the higher positively
charged ferric-ions create a slight magnetic field.
The minerals
that are magnetic, range in magnetic strength from
being capable of lifting small steel objects to barely
turning the needle on a compass.
A few minerals
may not be magnetic, but are still attracted to
magnets. Once a specimen is established as magnetic,
identification becomes a rather routine exercise.
A Quality Compass
As
A Field Test Tool - Magnetism is somewhat of an
unreliable property; as not all specimens may
demonstrate magnetism. While the presence of magnetism may
all but clinch an identification, the lack of
magnetism should not generally exclude typically
magnetic minerals. A high-quality compass needle is a good test-device for testing magnetism, as is a magnet on a
string that might sway near the specimen.
The Common
Minerals That Demonstrate Magnetic Properties
Strong
Attach To
Magnets
Weak
In Regards To A Metal
Detector, All Of The Above Become An
Issue To The Professional Metal Detector
User When Searching In Ground-Buried
Searching Applications. |
| Magnetite; A Natural Magnet
Magnetite is a mineral with a
defined element structure.
There Is A Combination Of Two Different
Metal Ions Occupying A Specific
Location Within The Structure.
The Metal Fe +2, And, The Metal Fe +3,
Are Two Different Metal Ions Within
Specific Locations Of The Structure.
The Two Different Metals Causes A
Transfer Of Electrons Between Them
In A Defined Direction (Vector). This Electric Vector
Generates A Magnetic Field.
This Magnetic Field Is What Is
Detected By A Metal Detector.
A Common Name For Magnetite Is "Lode
Stone". Magnetite Will Stick
To A Magnet.
Another Common Name For Magnetite Is
"Black Sand".
Gold Prospecting Note.
Gold Nuggets And "Black Sand" Are
Commonly Found Together In Many
Parts Of The World. Gold
Nugget Prospectors Can Use A Magnet
To Pull Black Sand From Their Gold
Pan Concentrates, Leaving The Gold
Dust Behind.
PHYSICAL CHARACTERISTICS
Color is black
Luster is metallic to dull
Transparency: Crystals are
opaque
Crystal Habits most commonly
found massive or granular
Hardness is 5.5 - 6.5
Specific Gravity is 5.1+
(average for metallic minerals)
Streak is black
Chemical Formula Fe++Fe+++2O4
Empirical Formula Fe3+2Fe2+O4
Associated Minerals are
talc and chlorite (schists),
pyrite and hematite.
Other Characteristics:
Magnetism stronger in massive
examples than in crystals,
striations on crystal faces (not
always seen)
Notable Occurrences include
South Africa, Germany, Russia and
many localities in the USA
Best Field Indicators:
magnetism (Magnet Sticks To
Magnetite; Compass Response; Crystal
Habit and Streak
Environment Common accessory
mineral in igneous and metamorphic
rocks. Can be biogenically
produced by a wide variety of
organisms |
by Gene Casanova
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