A colloquial term for geology of igneous and metamorphic rocks, as opposed
to soft-rock geology. AGI
A mine in hard rock; esp. one difficult to drill, blast, and square up.
Hess
A worker competent to mine in hard rock. Usually used to indicate an
expert miner as compared with one fit only to mine in soft rocks.
Hess
Solid minerals, as distinguished from oil and gas, esp. those solid
minerals found in hard rocks. Williams
Mining that takes place in igneous and metamorphic rock by means of
drilling and blasting to extract the ore. SME, 1
A term used in Florida for pebbles and boulders of a hard massive
homogeneous light-gray phosphorite, showing irregular cavities that are
usually lined with secondary mammillary incrustations of calcium
phosphate. It is essentially equivalent to the term "white-bedded
phosphate" that is used in Tennessee. AGI
A technique utilizing a machine called a boring machine to bore large
horizontal openings in rock or coal.
a. A commercial term for the larger sizes of dull, hard coal, in contrast
to brights. BS, 4
b. See:durain
c. In the United States, this term is used for anthracite.
Tomkeieff
See:seat earth
Any solder that melts only at a red heat; used in soldering silver, etc.
Fay
See:handpicking
A name applied to both corundum and andalusite. Fay
Due to the arrangement of the molecules within some mineral crystals, such
as diamond, the substance is found to be harder in certain planes or
directions in relation to the axes of the mineral crystals. These hard
planes are referred to as hard vectors. CF:soft vector
Long
Water that does not lather readily when used with soap, and that forms a
scale in containers in which it has been allowed to evaporate; water with
more than 60 mg/L of hardness-forming constituents, expressed as CaCO (sub
3) equivalent. See also:hardness; total hardness of water;
temporary hardness of water. CF:soft water
a. A term used in slate quarrying to describe the third direction at right
angles to both slaty cleavage and rift, in which there is no tendency to
split. It is known as the hard way and designated locally as the sculp.
b. In granite quarrying, the direction at right angles to both rift and
run is called the hard way or head grain. See also:cutoff; tough way.
Sometimes spelled hardway. AIME, 1
Georgia bauxite containing less than 1% ferric oxide. Fay
A dust collector for belt conveyors used at the loading station. The
delivery pulley of the main gate conveyor is used to drive a scraper
chain. The latter is arranged to run at half the belt speed by means of
chains and sprockets, and the scraper chain runs at the bottom of a long
hopper to the point where the coal is delivered into the trams. The
underbelt fines are collected on the scraper chain after having been
released from the belt by means of a snub pulley. The whole arrangement is
housed in a sheet-steel cover to which rubber flaps are attached. Side
spillage and the escape of dust over the side of the trams is prevented by
means of rubber flaps. Mason
A heavy electric rotary drilling machine for blasting work in mine
tunneling. It consists of a chassis mounted on continuous tracks,
turntable, boom, drilling machines, and various controls, and can be
operated by two people. Nelson
A method for producing direct from ore an iron in the form of either
sinter or pig that is suitable for charging in steel furnaces. Ore,
limestone, and carbon in the form of coal, coke, or oil coke in the
proportions of 40:8:5 are dried, crushed to about 1/16 in (1.6 mm),
intimately mixed, and fed into the upper end of a sloping rotary kiln.
Osborne
Generally, any airborne particulate matter that is fibrogenic (harmful to
the respiratory system), carcinogenic (capable of causing cancer),
radioactive, or toxic. Hartman, 2
A hypothesis based largely on the dome theory, which states that there is
a certain harmless depth below which mining could be carried on without
risk of damage to the surface. Subsidence observations at present working
depths do not support this theory. Nelson