Resource Dictionary

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Halite
Rock salt
Hanging wall
The wall or rock on the upper or topside of an ore deposit.
Haulageway
Any underground entry or passageway that is designed for transport of mined material, personnel, or equipment, usually by the installation of track or belt conveyor.
Head grade
The average grade of ore fed into a mill.
Head section
A term used in both belt and chain conveyor work to designate that portion of the conveyor used for discharging material.
Headframe
The structure surmounting the shaft which supports the hoist rope pulley, and often the hoist itself.
Heading
A vein above a drift. An interior level or airway driven in a mine. In longwall workings, a narrow passage driven upward from a gangway in starting a working in order to give a loose end.
Heap leaching
A process whereby valuable metals, usually gold and silver, are leached from a heap, or pad, of crushed ore by leaching solutions percolating down through the heap and collected from a sloping, impermeable liner below the pad.
Hectare
An area of land equivalent to 10,000 square meters or 2.47 acres.
Hedging
Taking a buy or sell position in a futures market opposite to a position held in the cash market to minimize the risk of financial loss from an adverse price change.
Hematite
An oxide of iron, and one of that metal's most common ore minerals.
High grade
Rich ore. As a verb, it refers to selective mining of the best ore in a deposit.
High-grader
One who steals rich ore, especially gold, from a mine.
Hogsback
A sharp rise in the floor of a seam.
Hoist
The machine used for raising and lowering the cage or other conveyance in a shaft.
Hoisting
The vertical transport coal or material.
Holding company
A corporation engaged principally in holding a controlling interest in one or more other companies.
Horizon
In geology, any given definite position or interval in the stratigraphic column or the scheme of stratigraphic classification; generally used in a relative sense.
Hornfels
A fine-grained contact metamorphic rock.
Horse
A mass of waste rock lying within a vein or orebody.
Horseback
A mass of material with a slippery surface in the roof; shaped like a horse's back.
Horst
An upfaulted block of rock.
Host rock
The rock surrounding an ore deposit.
Hydraulic
Of or pertaining to fluids in motion. Hydraulic cement has a composition which permits it to set quickly under water. Hydraulic jacks lift through the force transmitted to the movable part of the jack by a liquid. Hydraulic control refers to the mechanical control of various parts of machines, such as coal cutters, loaders, etc., through the operation or action of hydraulic cylinders.
Hydrometallurgy
The treatment of ore by wet processes, such as leaching, resulting in the solution of a metal and its subsequent recovery.
Hydrothermal
A process where water heated by pressure and magma to high degrees interacts with the country rock to either precipitate (leach) minerals into deposits, or even cause metamorphic reactions leading to concentrations of mineralization.