35 grade 1 The classifcation of an ore according to the desired material in it or according to value 2 In surveying the gradient of a traveling way sluice slope etc hardrock minerals L ocatable minerals that are nei ther leasable minerals coal oil phosphate etc nor saleable mineral materials sand and gravel etc Hardrock minerals include copper lead zinc magnesium nickel tungsten gold silver benton ite barite feldspar fuorspar and uranium haulageway The main transportation tunnel for deep mines in which rail tracks have been laid for mine cars highwall Unexcavated face of exposed overbur den and coal in a surface mine or in a face or bank on the uphill side of a contour mine excavation hopper cars Open freight cars with a foor sloping to one or more hinged doors for discharging bulk materials in situ gasifcation The gasifcation of underground coal deposits through partial combustion jumbo drill rig A drill carriage on which several drills of drifter type are mounted Drills are cut ting tools designed to form a circular hole in rock metal wood or other material In mining drills are used for exploration core drilling holes for explo sives etc leaching The action of percolating liquid thr ough or e to remove the soluble parts lignite See ranks of coal liquefaction The process of converting coal into a synthetic liquid fuel similar in nature to crude oil andor refned products such as gasoline locatable minerals Those minerals primarily me tallics that can be claimed and mined on public lands under the General Mining Law these do not include minerals such as coal oil phosphate so dium sulfur or sand and gravel lode deposit An ore deposit usually referring to a vein or veins of ore that can be mined as a unit Can also refer to a tabular deposit of a valuable mineral confned within defnite boundaries longwall miner A deep mining machine that uses a steel plow or rotating drum that is pulled me chanically backandforth across a long face of coal The loosened coal falls onto a conveyor for removal from the mine Longwall mining is highly productive and accounts for about 50 percent of total US underground coal production man car A vehicle used to transport miners to the working sections of a deep mine metallic minerals Minerals with a high specifc gravity and metallic luster such as gold silver copper titanium rutile tungsten uranium tin lead iron etc In general the metallic minerals are good conductors of heat and electricity metallurgical coal Various grades of coal suitable for carbonization to make coke for steel manufac ture methane A gas formed naturally from the decay of vegetative matter similar to that which formed coal The principal component of natural gas methane is frequently encountered in underground coal mining operations and is kept within safe lim its through the use of extensive mine ventilation systems In recent years coalbed methane has been recognized as an important energy resource and its production for this purpose has increased mine mouth power plant A steamelectric power plant built close to a coal mine Because of this proximity the coal is often delivered to the plant by tramway or covered conveyor minerals Scientifcally a naturally formed inor ganic solid element or chemical compound with a limited range in chemical composition and with an orderly internal atomic arrangement that de termines crystalline structure and physical prop erties Legally an organic or inorganic substance occurring naturally with characteristics and eco nomic uses that bring it within the purview of min eral laws a substance that may be obtained under the applicable laws from public lands by purchase lease or claim G L O SSA R Y