Ratio of magnetic induction (B) to the inducing field of magnetic
intensity (H). With magnetic intensity lines of force per square
centimeter in air, and flux density lines in a substance placed in that
field, B/H is the magnetic permeability. When this is less than 1.0, the
substance is diamagnetic; above 1.0, paramagnetic; and when high,
ferromagnetic. Pryor, 3
A drain or inspection plug magnetized for the purpose of attracting and
holding iron or steel particles in a lubricant. Nichols, 1
The orientation of the constituent minerals within the rocks of the
Earth's crust conforming to the Earth's magnetic field as it existed at
the time the strata were deposited. See also:core orientation
Long
a. Either of two points on the Earth's surface where the lines of magnetic
force are vertical; an end of the axis of the Earth's magnetic polarity,
not coincident with a geographic pole, and continually changing its
position. The north magnetic pole is in northern Canada.
Standard, 2
b. Either of two nonstationary regions on the Earth that sometimes move
many miles in a day, toward which the isogonic lines converge, and at
which the dip is + or -90 degrees . Webster 3rd
c. The area on a magnetized part at which the magnetic field leaves or
enters the part. It is a point of maximum attraction in a magnet.
ASM, 1
See:magnetic method
See:pyrrhotite
Any process by which the output of a detector-amplifier system is recorded
on a magnetic recording medium. The advantages of such a system are that
the resulting records may be played back and converted into conventional
records with phase shifting, mixing, etc., between traces and with
filtering variations. Most modern magnetic recording is in digital form.
AGI
Heating ferrous iron ore in the presence of air in order to oxidize the
iron content, present in whatever form, to the magnetic oxide so that in a
subsequent operation it can be separated from the gangue by means of a
magnetic separator. Also, roasting a hematitic ore with scrap iron to
reduce it to magnetite. Osborne
A feeder that uses magnetized, power-operated rolls for separating and
delivering objects.
Branch of science that deals with magnetic phenomena. Osborne
a. The separation of magnetic materials from nonmagnetic materials, using
a magnet. This is an esp. important process in the beneficiation of iron
ores in which the magnetic mineral is separated from nonmagnetic material;
e.g., magnetite from other minerals, roasted pyrite from sphalerite, etc.
Newton, 1; Henderson
b. The use of permanent magnets or electromagnets to remove relatively
strongly ferromagnetic particles from paramagnetic and diamagnetic ores.
Pryor, 2
a. A device used to separate magnetic from less magnetic or nonmagnetic
materials. The crushed material is conveyed on a belt past a magnet.
ASM, 1
b. For medium solids recovery. A device in which medium solids are caused
to adhere, by magnetic means, to a conveying belt or drum, while a current
of water removes nonmagnetic particles that contaminate the medium.
BS, 5
A worldwide disturbance of the Earth's magnetic field, commonly with
amplitude of 50 to 200 gammas. It generally lasts several days, and is
thought to be caused by charged particles ejected by solar flares.
Magnetic prospecting usually has to be suspended during such periods.
AGI
A measure of the degree to which a substance is attracted to a magnet; the
ratio of the intensity of magnetization to the magnetic field strength.
See:susceptibility
The gamma (Gamma ), which equals 10-5 Oe (7.9577 X 10-4
A/m). AGI
See:declination
A geophysical instrument similar to the gravimeter in that absolute values
are not measured, but only the differences in vertical magnetic force
between field stations and a selected base station. Nelson
a. That property of iron, steel, and some other substances, by virtue of
which they exert forces of attraction and repulsion according to fixed
laws. Crispin
b. The science that is concerned with the conditions and laws of magnetic
force. Crispin
a. An isometric mineral, 8[FeOFe2 O3 ] ; spinel group; forms
series with jacobsite and with magnesioferrite; crystallizes in octahedra;
metallic; black; strongly ferrimagnetic; an accessory mineral in many
igneous rocks; a common detrital mineral; a major mineral in banded iron
formations and magmatic iron deposits; an ore of iron.
Syn:black iron ore; lodestone; magnetic iron ore; octahedral iron ore.
See also:iron ore
b. The mineral series magnesioferrite, magnetite, maghemite, franklinite,
jacobsite, and trevorite in the spinel group. Syn:iron series
An igneous rock consisting essentially of magnetite and having an iron
content of 65% to 70% or more. Apatite may accompany the magnetite.
Johannsen
A dunite high in content of titaniferous magnetite and containing shreds
of biotite. Holmes, 2