a. Of a traverse, the amount by which the computed position of the last
point of the traverse fails to coincide with the initial point; i.e., the
length of line necessary to close the traverse. Frequently, also, the
ratio of the linear error of closure to the perimeter (also known as the
error of the survey). Seelye, 2
b. Of angles, the amount by which the sum of the measured angles fails to
equal the true sum. Seelye, 2
c. Of azimuths, the amount by which the measurement of the azimuth of the
first line of a traverse, made after completing the circuit, fails to
equal the initial measurement. Seelye, 2
d. Of a level circuit, the amount by which the last computed elevation
fails to equal the initial elevation; or the amount by which the
differences of elevation in a circuit fail to add up (algebraically) to
zero. Seelye, 2
e. Of a horizon, the amount by which the sum of the angles measured around
the horizon differs from 360 degrees . Seelye, 2
f. Of a triangle, the amount by which the sum of the three angles of a
triangle differs from the true sum; i.e., 180 degrees plus the spherical
excess. Seelye, 2
See:bornite
Said of a rock formed by the solidification of magma; i.e., either an
extrusive or an intrusive rock. Most writers restrict the term to its
extrusive or volcanic sense. AGI
See:erythrite
A monoclinic mineral, 2[Co3 (AsO4 )2 .8H2 O] ;
forms a series with annbergite and with hoernesite; occurs in soft pink to
crimson crystals, globular or reniform masses, or earthy encrustations as
a weathering product of cobalt ores in the oxidized parts of
nickel-arsenic-silver-bearing veins; used as ore indicator for cobalt and
possibly silver. Syn:erythrine
cobalt ocher; peachblossom ore.
See:eriochalcite
a. Eng. A second or additional shaft by which miners may get out of the
mine in case of accident to the other shafts. Also an upcast; escape pit;
escapeway.
b. A wasteway for discharging the entire flow of a stream.
Seelye, 1
A shaft driven esp. to permit egress from the mine in case of emergency.
BCI
An opening through which the miners may leave the mine if the ordinary
exit is obstructed. Fay
a. A long, more or less continuous cliff or relatively steep slope facing
in one general direction, breaking the continuity of the land by
separating two level or gently sloping surfaces, and produced by erosion
or by faulting. The term is often used synonymously with scarp, although
escarpment is more often applied to a cliff formed by differential
erosion. AGI
b. A steep, abrupt face of rock, often presented by the highest strata in
a line of cliffs, and generally marking the outcrop of a resistant layer
occurring in a series of gently dipping softer strata; specif. the steep
face of a cuesta. CF:cuesta
A mixture of two parts magnesium and one part dried sodium carbonate; used
as a reagent for determining sulfur in coal or coke. Hackh
See:aeschynite
A tetragonal mineral, CuFeSe2 ; chalcopyrite group; forms a series
with chalcopyrite; is metallic brass yellow; variably magnetic; with
chalcopyrite, clausthalite, and naumannite in dolomite veins, Eskeborn
adit, Tilkerode, Harz Mountains, Germany.
A trigonal mineral, Cr2 O3 ; hematite group; easily confused
with hematite and magnetite; in a chromium-bearing tremolite skarn at the
Outokumpu Mine, Finland.
A classifier of the free-settling type in which the settled material is
removed by dragging it up an inclined plane by means of a continuous belt
of flat blades or paddles. It is continuous in its operation.
Liddell
A broad bench or terrace bordering a canyon, esp. in the plateau areas of
the southwestern United States.
A conglomerate or breccia with rapid lateral passage through grit to fine
sandstone; cement usually ferruginous with some lime and alumina.
Characteristically developed amid variegated clays of Etruria Marl group
of Upper Coal Measures in the English Midlands. Arkell
A mineral component of a rock that is necessary to the classification and
nomenclature of the rock, but that is not necessarily present in large
amounts. CF:accessory mineral
An alkali gabbro primarily composed of plagioclase, hornblende, biotite,
and titanaugite, with lesser amounts of alkali feldspar and nepheline.
Essexite grades into theralite with a decrease in potassium feldspar and
an increase in the feldspathoid minerals. Its name is derived from Essex
County, MA. AGI
A yellow-brown or reddish-brown transparent gem variety of grossular
garnet containing iron. Syn:cinnamon stone; hyacinth; jacinth.
See:hessonite
A massive variety of apatite found in Estramadura, Spain. A phosphate ore.
Hey, 1; English