An eruptive iron ore occurring at Routivara, Sweden, and consisting of
magnetite (in part titaniferous), spinel, and smaller amounts of olivine,
pyroxene, apatite, and pyrrhotite. The ore contains about 14% titanic
oxide.
A body is said to be magnetized when it possesses or can be made to
possess that peculiar property whereby, under certain circumstances, it
will naturally attract or repel a similar body in accordance with magnetic
laws; e.g., drill rods become magnetized in use and will strongly attract
other iron or steel articles. Long
a. The phenomenon associated with a magnetic flux density at a point.
Theoretically, measured by the mechanical force on a unit magnetic pole in
an evacuated tunnel along the direction of the magnetic flux; the
magnetomotive force per centimeter in this direction. CTD
b. A force field, resulting from the flow of electric currents or from
magnetized bodies, that produces magnetic induction. ASM, 1
A process in which an ore containing pyrite is heated and the magnetic
iron oxide so formed is removed by a magnetic separator. In many cases the
iron oxide is extracted as gangue. Nelson
a. An instrument for measuring magnetic intensity. In ground magnetic
prospecting, an instrument for measuring the vertical magnetic intensity;
in airborne magnetic prospecting, an instrument for measuring the total
magnetic intensity. Also, an instrument used in magnetic observatories for
measuring various components of the magnetic field of the Earth.
AGI
b. A sensitive instrument for detecting and measuring changes in the
Earth's magnetic field, used in prospecting to detect magnetic anomalies
and magnetic gradients in rock formations.
See also:airborne magnetometer
a. A hexagonal mineral, Pb(Fe,Mn)12 O19 ; black;
ferrimagnetic; at Laangban, Sweden.
b. The mineral group hawthorneite, hibonite, magnetoplumbite, and
yimengite.
A form of transmission based on the principle that a magnetic field of
force is produced whose strength is varied so as to transmit a torque of
corresponding magnitude. With a system of this kind, control of any
particular operation is effected through the agency of the magnetorque
clutch, while the motor runs continuously at constant speed.
Mining
The characteristic of a material that is manifest by strain when it is
subjected to a magnetic field; or the inverse. Some iron-nickel alloys
expand; pure nickel contracts. ASM, 1
a. An electrical prospecting technique based on an application of telluric
currents in which the magnetic fields induced by the alternations in earth
currents would be measured simultaneously with the voltage fluctuations
between electrodes at the surface. The ratio between the amplitudes of
these alternating voltages and the associated magnetic fields would be
plotted as a function of frequency. Dobrin
b. An electromagnetic method of surveying, in which natural electric and
magnetic fields are measured. Usually the two horizontal electric-field
components plus the three magnetic-field components are recorded;
orthogonal pairs yield elements of the tensor impedance of the Earth. This
impedance is measured at frequencies within the range 10-5 Hz to
10 Hz. AGI
A monoclinic mineral, (Mg,Fe,Mn)2 (PO4 )F ; yellow.
A variety of chromite that contains magnesium. Alternate spelling of
magnesiochromite. Standard, 2
An orthorhombic mineral, (Mg,Fe,Mn)(Nb,Ta)2 O6 .
CF:columbite
Original form of magnesioferrite. Dana, 1
An isometric and tetragonal mineral, Mn5 As3 O9
(OH,Cl) ; green; forms crusts at Laangban, Sweden, and green to brown
selvages at Sterling Hill, NJ.
Compact mixture of oxides of iron and copper. Schaller
A softer sort of limestone, very dusty. Arkell
a. The road along which the principal ventilating current passes.
Peel
b. Underground ventilation channel directly connected with a shaft or
other entry to a mine. Pryor, 3
A single-track haulage system operated by a haulage engine with two drums,
each with a separate rope. The engine is usually located at the out end of
the system. The main rope is attached to the out end of the set of tubs,
and the tail rope passes around a sheave in, and is then attached to, the
rear end of the set. To draw the full set out, the main rope is wound in,
the tail rope being allowed to run free. To draw the empty set in, the
tail rope is wound in, the main rope being allowed to run free. The tail
rope is equal to twice the length of the haulage road. The main-and-tail
haulage is adopted when the gradient is irregular and the empty set will
not run in by gravity. See also:rope haulage
a. The refractory blocks forming the part of a horizontal gas retort
comprising the division walls and the roof that covers the retorts and the
recuperators. Dodd
b. General term for the central part of a furnace roof, particularly used
as a syn. for the crown of a glass tank furnace. Dodd
York. The heading that is driven slightly to the rise from the shaft.
Fay
Hard rock below alluvial deposits.