A monoclinic mineral, BaMn8 O16 ; cryptomelane group;
pseudotetragonal; massive, botryoidal, stalactitic, or prismatic with
deeply striated faces; commonly associated with pyrolusite.
CF:romanechite
A dam built of reinforced concrete, mass concrete, or masonry in which the
water pressure is resisted by a sloping slab or vault carried by
buttresses. Hammond
A pump used for mining and quarrying, as in muddy and gritty water.
Standard, 2
Recessed masonry that carries the heel post of a lock gate.
Hammond
A churn drill in which hollow rods replace the steel wire rope. The
drilling fluid is pumped down the inside of the rods, and the chipping and
fluid return to the surface on the outside. Nelson
Eng. Old abandoned workings. Fay
A drill support consisting of a cylinder of about 2-in (5.1-cm) bore in
which the piston is actuated by compressed air controlled by a twist-grip
control valve. This valve is also used to release the air pressure to
allow the piston to be lowered. The control valve also regulates the
feeding pressure on the drill. The length of feed of the Holman Airleg is
39 in (99 cm), overall length 57 in (145 cm), and weight 25 lb (11.4 kg).
A vent hole near the top of the cylinder allows the air to escape when the
piston travels past it, so as to warn the operator that the limit of feed
has been reached. The leg is then readjusted for drilling to be resumed.
The leg gives good support to the drill at all heights within reasonable
limits, and one person can comfortably handle a drill when mounted in this
way. Mason
Holman counterbalanced drill rig
A drill rig consisting of a rail-track carriage on which is mounted a
counterbalanced boom 10 ft (3 m) in length. For two-drill mounting, a
crossbar is attached to the boom, and drill cradles can be fixed over or
under the bar by swinging it through 180 degrees . For a four-drill
mounting, two additional vertical columns are used; these are jacked to
the floor and the drill carriage clamped to the track. The crossbars can
be clamped to any required position on the vertical columns. Mason
A dust trap in which the dust and chippings created during percussive
drilling are drawn back through the hollow drill rod and out through the
rear of the machine and along a hose to a metal container with filter
elements. The appliance requires a special type of drilling machine, rods,
and bits. See also:dust trap
A method of sintering iron ore. Sintering is carried out in a series of
pans, 11 ft 6 in (3.5 m) square, with robust chromium vanadium steel grate
bars, which have a life of 5 to 6 years. Advantages include low fuel
consumption and absence of moving parts in the sintering zones.
Osborne
A device that takes samples with a scoop rotating on an axle mounted on a
heavy frame that rests firmly on the bottom. The device is lowered open
with the entire weight taken by a shackle on a balanced arm. Closure is
not effected on touching bottom. On hoisting, the pressure of water on a
vane attached to the balanced arm tips a lever allowing a pin to slip out,
releasing the shackle. The weight is then transferred to a rope rotating
around a large drum. This in turn rotates a small pulley and drags the
sampling hemisphere through the bottom via a second pulley to which it is
attached by a light wire. The maximum volume of the sample is 5« L, and in
practice, usually about 3 to 4 L are collected. Hunt
A sampling device using force provided by a vacuum chamber (containing air
at atmospheric pressure) to suck in a sediment sample. On striking the
bottom, the chamber is put into communication with the outside. Water
pressure forces the sample into the collecting tube. The pressure chamber
itself is a strong brass tube closed at the upper end by a lid and held
firmly in position by a clamp. A sampling tube is fixed below the chamber
and extends upward into it. Between the upper and lower parts of the
central tube is a plug held in position by retaining hooks through slots
in the wall of the lower tube. When the device strikes the bottom, a mouth
tube rises, disengaging the plug, which flies up the tube. The water then
forces material up into the collecting tube. Hunt
An orthorhombic mineral, Li2 (Fe,Mg)3 Al2 Si8
O22 (OH)2 ; amphibole group, with Mg/(Mg+Fe2+ ) =
0.1 to 0.89 ; in granite pegmatites.
An epoch of the Quaternary period, from the end of the Pleistocene,
approx. 10,000 years ago, to the present time; also, the corresponding
series of rocks and deposits. When the Quaternary is designated as an era,
the Holocene is considered to be a period. Syn:Recent
Said of the texture of an igneous rock composed entirely of crystals,
i.e., having no glassy part. Also, said of a rock with such a texture.
AGI
The point group with the highest symmetry of its crystal system.
CF:hemihedral; merohedral; crystallographic system.
Said of an igneous rock that is composed entirely of glass. AGI
Coalified remains of entire plants. Tomkeieff
a. A soft sandstone used to scrub a ship's decks. Webster 3rd
b. To scrub with a holystone. Webster 3rd
c. Eng. Limestone full of holes, white limestones of the Great Oolite near
Minchinhampton, Gloucestershire, used for megalithic monuments.
Arkell
d. Pumice or friable sandstone used to scrub a ship's deck.
N. of Eng. In the direction of, or toward, the shaft, as in an underground
mine. Outby. Fay
Pertaining to a type of crystalloblastic texture in a metamorphic rock in
which the essential mineral constituents are approx. of equal size.
CF:crystalloblastic; heteroblastic. AGI