A substance with a distinctive, disagreeable odor put in the air current
to warn underground workers of fire or other emergency; ethyl mercaptan is
commonly used. Hess
A fire-warning device designed to be bolted to a flat surface that may
rise to a dangerous temperature. It consists of a cavity filled with 20 cm
3 of ethyl or butyl mercaptan alone or with other stench agents
and is sealed with a fusible plug in a brass container with a hexagonal
head, arranged to liberate the stench agent at any temperature chosen.
Tests in pits have shown that a strong smell could be detected 1.7 miles
(2.7 km) from the discharge point 25 to 30 min after the device operated.
Sinclair, 1
A monoclinic mineral, (Sr,Ba,Na)2 Al(CO3 )F5 .
a. The amount of work expected from a coal miner in a day or week.
See also:stint
b. See:pitch
c. Corn. Tourmaline and quarz veins in kaolinized granite.
d. U.K. Rubble; waste.
e. U.K. Extent or limit, as of a pitch or bargain.
N. of Eng. See:stenton
A connecting roadway between two adjacent roadways that may be used for
ventilation purposes. Also called air slit; crosscut; cross hole;
thirling; througher; spout. Syn:crosscut
breakthrough; pillar-and-stall. BS, 8
a. Fault; a small fault; a small fault in a stepped series of faults.
Mason
b. A small offset on a piece of core or in a drill hole resulting from a
sudden sidewise deviation of the bit as it enters a hard, tilted stratum
or rock underlying a softer rock. CF:kick
c. One of several terracelike or stairstep concentric configurations on
the crown of a diamond bit. See also:step-face bit
d. A treatment of one part of a sample in a sample divider (thus a pass
consists of one or more steps). BS, 3
e. The action of setting a lock gate into a vertical position.
Hammond
a. A mode of cutting gems in steplike facets. Standard, 2
b. A form of cutting employed for stones not deeply colored when they are
not cut as brilliants; a simple typical form is that of a stepped pyramid
with the apex sliced off. Also called trap cut. Hess
c. A style of cutting, widely used on colored gemstones, in which long,
narrow, four-sided facets form in a series or row parallel to the girdle
and decrease in length as they recede above and below the girdle, giving
the appearance of steps. The number of rows, or steps, may vary, although
it is usually three on both the crown and pavilion. Different shapes of
step cuts are described by their outline; e.g., rectangular or square step
cut. Syn:trap cut
A thin-nosed bit with diamonds set in several concentric terracelike rows
that form the outside wall. Long
a. One of a set of parallel, closely spaced faults over which the total
displacement is distributed. CF:fault zone
distributive fault. AGI
b. One of a series of low-angle thrust faults in which the fault planes
step both down and laterally in the stratigraphic section to lower glide
planes. Step faulting is due to variation in the competence of the beds in
the stratigraphic section. AGI
c. A series of parallel faults that, all inclined in the same direction,
gives rise to a gigantic staircase; hence these are called step faults.
Each step is a fault block and its top may be horizontal or tilted.
AGI
An orthorhombic mineral, Ag5 SbS4 ; soft; metallic; sp gr,
6.2 to 6.3; in veins; a source of silver. Syn:brittle silver ore;
black silver; goldschmidtine.
An early type of coal miners' lamp. It had a glass chimney surrounded by a
wire gauze about 2 in (5.1 cm) in diameter. The glass chimney was covered
by a perforated copper cap, and the air was fed to the flame from below
through small holes and wire gauze in a lateral extension of the oil
vessel. The lamp was unsafe; it passed flame when the velocity of the air
current exceeded about 8 ft/s (2.4 m/s). See also:safety lamp
Nelson
An extensive, treeless grassland area in the semiarid mid-latitudes of
southeastern Europe and Asia. It is generally considered drier than the
prairie which develops in the subhumid midlatitudes of the United States.
AGI
A system of longwall stalls in which the faces are carried forward in a
steplike formation, one stall about 5 yd (4.6 m) in advance of the next
stall. It is claimed to have advantages when the roof is friable.
See also:top holes
The term implies that mining at one face is stepped aside from that below
so as not to hinder the work at it. Syn:advance stope
Term used in dredging operations when the digging spud is dropped, the
other spud is raised, and the dredge is ready to begin a new cut.
Lewis
See:step vein
A special form of socket for use on locked-wire rope. Zern
To increase the voltage of (a current) by means of a transformer.
Webster 3rd
A vein alternately cutting through the strata of country rock and
conforming with them. Syn:step reef