A joint found in rocks that causes a plane of weakness known variously as
a rift or gain. This largely determines the shape of the blocks that may
be extracted from a quarry. Also called incipient joint. Syn:gain
A soil-sampling auger made by spirally twisting a flat steel ribbon to
form a tubelike, hollow-center, corkscrewlike device. Long
See:cup and cone
a. A surveying traverse whose accuracy can be checked by the fact that,
when it is closed, the angles should add up to 360 degrees , and which
ends at its starting point. Hammond
b. A surveying traverse that starts and terminates upon the same station
or upon a station of known position. CF:open traverse
The separation of solids from a washery slurry so that the water can be
returned to the plant and used continuously. Nelson
a. Pure stones, of desirable shapes.
b. Highest class of South African diamonds, as sorted at Kimberly.
Applied to rocks in which the joints are very close together. Fay
See:slip cleavage
A nipple, the length of which is about twice the length of a standard pipe
thread and without any shoulder. See also:nipple
Detailed analysis of a proven placer deposit that should determine: (1)
the volumetric measurements of both overburden and gravel; (2) the
estimation of the gold or other mineral contents; (3) the average value of
the area in pence, cents, carats, or other unit per unit of volume; and
(4) all possible information regarding the nature of the overburden and
gravel--i.e., whether it is clayey, free wash, etc.--as well as of the
bedrock. Griffith
Screened or classified between close maximum and minimum limits of size or
settlement. Pryor, 4
Consists of planks placed side by side along a continuous frame. Its use
is to prevent local crumbling of less compacted soils. Since crevices can
exist between planks, it should not be used with fine silts or liquid
soils, which can seep through these cracks. CF:skeleton sheathing;
tight sheathing. Carson, 1
a. In screening, choice of sieve sizes that are fairly close in mesh size
to restrict size range of each fraction of the material separated.
b. Sizing with screens.
The setting of timber sets and lagging very close together when shaft
sinking or tunneling through very loose ground or crushed coal in thick
seams. See also:cribbing; forepoling. Nelson
When calculating or plotting the distances, angles, or coordinates of a
closed traverse or one connecting two accurately located points, the
discrepancy between starting and finishing point. This error is adjusted
in proportion to the magnitude of the angles and distances involved, if it
is below a tolerable limit. See also:error of closure
Operating rope for opening and closing a grab. Hammond
Dense, laminated, brownish-red algal coal found in Irkutsk, Russia. It
consists of an accumulation of spheroidal algal colonies of different
sizes, among which are disseminated great numbers of desmid algae,
belonging to the living genus, Closterium. Tomkeieff
a. A closed anticlinal structure.
b. The difference in the relative position of the bottom and the collar of
a borehole expressed in horizontal distance in a specific compass
direction. Long
c. The relative inward movement of the two walls of a stope.
d. A cumulative measure of the various individual errors in survey
measurements; the amount by which a series of survey measurements fails to
yield a theoretical or previously determined value for a survey quantity.
AGI
e. Used in structural geology, esp. in connection with potential oil
structures, to designate the vertical distance between the highest point
of an anticlinal structure of an anticlinal structure or fold and the
lowest contour that closes around the structure. It is an approximate
measure of the capacity of a structural trap for oil and/or gas.
Stokes
f. A portion of brick to close, when required, the end of a course as
distinguished from a half brick. See:closure
An instrument for indicating the amount of closure that has taken place.
Wall closure in mines is measured by this instrument. Also called sag
meter. Spalding; Spalding
A group of ferromagnesian minerals in igneous rock, from a few inches to a
foot or more in size, commonly drawn out longitudinally, that may be a
segregation or an altered xenolith. AGI
Eng. Brattice constructed of a coarse, specially prepared canvas.
Fay