a. Any member of the trigonal mineral group, XY3 Z6 (BO (sub
3) )3 Si6 O18 (OH,F)4 where X is Na partially
replaced by Ca, K, Mg, or a vacancy, Y is Mg, Fe2+ , Li, or Al,
and Z is Al and Fe3+ ; forms prisms of three, six, or nine sides;
commonly vertically striated; varicolored; an accessory in granite
pegmatites, felsic igneous rocks, and metamorphic rocks. Transparent and
flawless crystals may be cut for gems.
b. The mineral group buergerite, dravite, elbaite, ferridravite,
liddicoatite, schorl, and uvite.
Introduction of, or replacement by, tourmaline. AGI
A channel-type, steel-arch support consisting of three elements or
sections set close to the face of a tunnel. These elements overlap and
yield by sliding one upon the other under the constraint of bolted clamps.
The center or crown element is usually foreset to give temporary
protection until the complete arch is erected. See also:Usspurwies arch;
steel arch; steel support. Nelson
An endless chain supported by trolleys from an overhead track or running
in a track at (above, flush with, or under) the floor with means for
towing trucks, dollies, or cars.
See:grader
a. See:tour
b. A misnomer for derrick and an incorrect spelling of tour. Long
A swing-jib or other type of crane mounted on top of a tower, the base of
which may sometimes move on rails. These cranes are esp. effective on
congested sites. See also:monotower crane; swing-jib crane.
Hammond
In anthracite coal mining, one who operates a hoist to raise loaded mine
cars from the surface of a mine to the top of the breaker, where the coal
is dumped, crushed, and prepared for market. DOT
A cableway excavator designed specif. for levee work, but which is used
extensively in the stripping of overburden, spoil, or waste in surface
mining. The unit is basically an excavator with towers either fixed or
movable. With the headtower located on the spoil pile and the tail tower
on the unexcavated wall, it is possible to dig pits of almost unlimited
width.
A front-end loader whose bucket is lifted along tracks on a more or less
vertical tower. Nichols, 1
A device utilizing a rotating field of magnetic force to induce a vigorous
rotary movement in a small magnetized bar totally enclosed in a polythene
or glass tube, and placed in the liquid to be stirred. Osborne
The unit of survey of the U.S. Public Land Survey system, representing a
piece of land that is bounded on the east and west by meridians approx. 6
miles (9.6 km) apart (exactly 6 miles at its south border) and on the
north and south by parallels 6 miles apart, and that is normally
subdivided into 36 sections. Townships are located with reference to the
initial point of a principal meridian and base line, and are normally
numbered consecutively north and south from a base line (e.g., township 14
north indicates a township in the 14th tier north of a base line). The
term township is used in conjunction with the appropriate range to
indicate the coordinates of a particular township in reference to the
initial point (e.g., township 3 south, range 4 west indicates the
particular township that is the 3rd township south of the base line and
the 4th township west of the principal meridian controlling the surveys in
that area). Abbrev. (when citing specific location): T. AGI
One of the imaginary boundary lines running east and west at 6-mile
(9.6-km) intervals and marking the relative north and south locations of
townships in a U.S. public land survey. CF:range line
Dusts poisonous to body organs, tissue, etc. They include ores of
beryllium, arsenic, lead, uranium, radium, thorium, chromium, vanadium,
mercury, cadmium, antimony, selenium, manganese, tungsten, nickel, and
silver (principally the oxides and carbonates). Hartman, 2
In geochemical exploration, a collective term for the abnormal colors and
morphological features of a plant caused by a poisonous element in the
nutrient solution. Hawkes, 1
Water that is discharged from active or abandoned mines or other areas
affected by mineral exploration or surface mining and reclamation
operations that contains a substance that through chemical action or
physical effects is likely to kill, injure, or impair biota commonly
present in the area(s) to which it might be exposed.
See:tossing
a. A concentration of a substance that is detectable, but too minute for
accurate quantitative determination. AGI
b. A quantity of precipitation that is insufficient to be measured by a
gauge. AGI
c. A sign, evidence, or indication of a former presence; specif. a mark
left behind by an extinct animal, such as a trace fossil. AGI
d. The record of the output of one geophone group with time after the
shot, displayed on paper, film, or magnetic tape. AGI
e. The intersection of a geological surface with another surface, e.g.,
the trace of bedding on a fault surface, or the trace of a fault or
outcrop on the ground. CF:trend; strike. AGI
f. A very small quantity of a chemical constituent or component, esp. when
not quantitatively determined because of extremely low concentrations.
g. To follow the lode on the surface, and to lay it open by long pits.
Fay
h. Recording on the seismogram of a single seismometer station.
Schieferdecker
A procedure used in seismic reflection where reflection times from all
traces, or sometimes alternate traces, are plotted at the reflecting point
positions (midway between shot and detector). When no correction has been
made for "normal moveout," the plotted times appear to lie along arcs that
are convex upward and straddle the shot positions symmetrically.
CF:center-trace time
a. An element that is not essential in a mineral, but that is found in
small quantities in its structure or adsorbed on its surfaces. Although
not quantitatively defined, it is conventionally assumed to constitute
significantly less than 1.0% of the mineral. Syn:accessory element;
guest element. AGI
b. An element that occurs in minute quantities in plant or animal tissue
and that is essential physiologically. Syn:minor element; microelement.
AGI
An element or compound that has been made radioactive so that it can be
followed (traced) easily in industrial and biological processes. Radiation
emitted by the tracer (radioisotope) pinpoints its location. Abbrev., tcr.
Lyman; Zimmerman