Appendix:Dictionary of Mining, Mineral, and Related Terms/N/2

noble
 * a. A term used to express great value or purity, as in a noble metal (e.g., platinum); or inertness, as in a noble gas (e.g., helium). See also: noble gas; noble metal.

b. An adj. usually modifying "metal" or "gas" and referring to those elements which do not normally combine with oxygen or other non-metallic elements under near-surface conditions; thus they commonly occur as native elements (or alloys). The metals usually included are gold, silver, platinum, palladium, ruthenium, iridium, rhodium, and osmium; the gases are helium, neon, argon, krypton, xenon, and radon. Other elements found in their native states, such as sulfur, copper, or mercury, are not noble because they spontaneously (even though slowly) oxidize.

noble gas
 * A rare inert gas: helium, neon, argon, krypton, xenon, and radon. Syn: inert gas. See also: noble.

nobleite
 * A monoclinic mineral, CaB (sub 6) O (sub 9) (OH) (sub 2) .3H (sub 2) O ; tabular or mammillary; transparent; formed by the weathering of colemanite and priceite in Death Valley, CA.

noble metal
 * A metal with marked resistance to chemical reaction, particularly to oxidation and to solution by inorganic acids. The list includes mercury and the precious and platinum-group metals. CF: base metal. See also: noble.

no-cut rounds
 * In blasting underground, drilling all holes straight into the face.

nodular
 * a. Composed of nodules; e.g., nodular bedding consisting of scattered to loosely packed nodules in matrix of like or unlike character.

b. Having the shape of a nodule, or occurring in the form of nodules; e.g., nodular ore such as a colloform mineral aggregate with a bulbed surface. c. Orbicular.

nodular cast iron
 * A cast iron that has been treated while molten with a master alloy containing an element, such as magnesium or cerium, to produce primary graphite in the spherulitic form. See also: iron.

nodular structure
 * See: orbicular structure.

nodule
 * a. A small, irregularly rounded knot, mass, or lump of a mineral or mineral aggregate, normally having a warty or knobby surface and no internal structure, and usually exhibiting a contrasting composition from the enclosing sediment or rock; e.g., a nodule of pyrite in a coalbed, a chert nodule in limestone, or a phosphatic nodule in marine strata. Nodules can be separated as discrete masses from the host material.

b. One of the widely scattered concretionary lumps of manganese, cobalt, iron, and nickel found on the floors of the world's oceans; esp. a manganese nodule. Etymol: Latin nodulus, small knot. CF: concretion. c. A rounded material accretion built of successive layers, of easily handled size. d. A small, rounded, irregularly shaped mass, as those of graphite in malleable cast iron.

nodulizing
 * a. The forming of rounded shapes by the application to fine coal of a gyratory, rotary, or oscillatory motion, without the use of pressure.

b. See: balling.

noise
 * a. Any undesired sound.

b. By extension, any unwanted disturbance such as undesired electric waves in any transmission channel or device. c. In gravity and magnetic prospecting, disturbances in observed data due to more or less random inhomogeneities in surface and near-surface material. d. In seismic prospecting, all recorded energy not derived from the explosion of the shot. Sometimes loosely used for all recorded energy except events of interest.

noise level
 * In observed or recorded data, the fluctuations not attributable to signals.

noise reduction rating
 * A measure of a hearing protector's effectiveness in reducing noise such as results from mining operations where drilling, cutting, blasting, etc. create high noise levels. Abbrev. NRR.

nolanite
 * A hexagonal mineral, (V,Fe,Ti) (sub 10) O (sub 14) (OH) (sub 2) ; rare; forms tabular prisms and plates; associated with uranium ores at Beaverlodge, SK, Canda, and with native gold and various tellurides at Kalgoorlie, Western Australia.

nominal area
 * Of a screen, the total area of the screen deck exposed to the flow of the material feed.

nominal bandwidth
 * In a filter, the difference between the nominal upper and lower cutoff frequencies. This difference may be expressed in cycles per second, as a percentage of the pass-band center frequency, or as the difference between the upper and lower cutoffs in octaves.

nominal capacity
 * A notional figure expressed in tons per hour used in the title of a flowsheet and in general descriptions of the plant, applying to the plant as a whole and to the specific project under consideration. It may be taken as representing the approximate tonnage expected to be supplied to the plant during the hour of greatest load.

nominal price
 * An estimate of the price for a future month date which is used to designate a closing price when no trading has taken place in that date. Also used for current price indications in similar circumstances in physical trading.

nominal screen aperture
 * a. A nominal mesh aperture used to designate the result of a screening operation.

b. A notional size at which it is intended to divide a feed by a screening operation. Syn: nominal screen size.

nominal screen size
 * See: nominal screen aperture.

nominal size
 * The limit or limits of particle size used to describe a product of a sizing operation.

nomogram
 * A type of line chart that graphically represents an equation of three variables, each of which is represented by a graduated straight line. It is used to avoid lengthy calculations; a straight line connecting values on two of the lines automatically intersects the third line at the required value. Syn: nomograph.

nomograph
 * See: nomogram.

nonangular unconformity
 * See: disconformity.

nonasphaltic pyrobitumen
 * Any of several species of pyrobitumens, including dark-colored, comparatively hard and nonvolatile solids, composed of hydrocarbons containing oxygenated bodies, infusible and largely insoluble in carbon disulfide. This includes peat, coal, and nonasphaltic pyrobitumen shales.

nonbanded coal
 * Coal that does not display a striated or banded appearance on the vertical face. It contains essentially no vitrain and consists of clarain or durain, or of material intermediate between the two.

non-Bessemer ore
 * Ore containing up to about 0.18% phosphorus.

noncaking coal
 * Coal that does not form cake; namely hard, splint, cherry, and durain coal.

noncaving method
 * Any of several stoping methods, including open stopes, sublevel, shrinkage, cut-and-fill, and square set.

noncoal mine
 * A mine in which the material being mined is incombustible or contains at least 65% by weight of incombustible material, and in which the underground atmosphere in any open workings contains less than 0.25% by volume of flammable gas.

noncoking coal
 * A bituminous coal that burns freely without softening or any appearance of incipient fusion. The percentage of volatile matter may be the same as for coking coal, but the residue is not a true coke.

noncombustible
 * Any material that will neither ignite nor actively support combustion in air at 1,200 degrees F (649 degrees C) when exposed to fire. See also: incombustible.

nonconformable
 * Pertaining to the stratigraphic relations shown by a nonconformity.

nonconformity
 * a. An unconformity developed between sedimentary rocks and older rocks (plutonic igneous or massive metamorphic rocks) that had been exposed to erosion before the sediments covered them. The restriction of the term to this usage was proposed by Dunbar & Rodgers (1957). Although the term is well known in the classroom, it is not commonly used in practice (Dennis, 1967).

b. A term that formerly was widely, but is now less commonly, used as a syn. of angular unconformity, or as a generic term that includes angular unconformity. Term proposed by Pirsson (1915).

nonconsumable-electrode arc melting
 * A method of arc melting in which a carbon or tungsten electrode is used and the sponge metal to be melted is fed into the arc at the proper rate.

noncore bit
 * See: plug bit.

noncore drilling
 * Drilling a borehole without taking core.

noncoring bit
 * A general type of bit made in many shapes that does not produce a core and with which all the rock cut in a borehole is ejected as sludge. Used mostly for blasthole drilling and in the unmineralized zones in a borehole where a core sample is not wanted. Also called blasthole bit; plug bit. CF: fishtail bit; roller bit. Syn: blind bit.

nondestructive testing
 * Methods of examination, usually for soundness, which do not involve destroying or damaging the material or part being tested. It includes radiological examination, magnetic inspection, etc. Also called nondestructive inspection.

nondiamond core drill
 * A rotary or percussive-type drill equipped with core-cutting tools or bits, the cutting points of which are not inset with diamonds.

nonel
 * See: nonelectric blasting.

nonelectric blasting
 * The firing of one or more charges using safety fuse, igniter cord, detonating cord, shock or gas tubing, or similar nonelectric materials to initiate a blasting cap. Syn: nonel. See also: gas detonation system; shock tube system.

nonelectric delay blasting cap
 * A detonator with an integral delay element and capable of being initiated by miniaturized or regular detonating cord.

nonferrous
 * Of, or relating to, a metal or compound that does not contain appreciable quantities of iron; ores that are not processed primarily for their iron content.

nonferrous alloy
 * Specif., an alloy containing no iron. Generically, any alloy that has as its base any element other than iron. Common commercial nonferrous alloys are based upon aluminum, copper, lead, magnesium, nickel, tin, and zinc.

nonferrous metallurgy
 * That branch of metallurgy that deals with the broad field of metals other than iron, or alloys other than of iron base. CF: ferrous metallurgy.

nonferrous metals
 * a. Classification of metals that are not commonly associated with alloys of iron, including base metals, precious metals, and light metals.

b. In singular form, an alloy that has as its base metal a metal other than iron, e.g., copper, lead, aluminum, etc.

nonflowing well
 * A well that yields water at the ground surface only by means of a pump or other lifting device. See also: artesian well.

nonfreezing explosive
 * Explosive to which 15% to 20% of nitroethylene glycol has been added. This acts as a freezing-point depressant and prevents freezing at ordinary temperatures. Polar or Arctic explosives are nitroglycerin explosives of this type.

nongraded sediment
 * a. In geology, detrital sediment, loose or cemented, containing notable amounts of more than one grade; e.g., loam or boulder clay. Syn: poorly sorted.

b. In engineering, sediment in which the constituent particles are all of nearly the same size.

nonhardening salt
 * Salt containing substantial quantities of impurities such as calcium and/or magnesium chloride, which are highly deliquescent and prevent caking.

nonluminous flame
 * Hydrogen, carbon monoxide, or aerated coal gas flames.

nonmagnetic rod
 * A drill rod made of brass, aluminum, or other metal unaffected by magnetism.

nonmagnetic steel
 * Steel alloyed with 12% or more of manganese, chromium, or nickel. Such an alloy cannot be removed from a passing stream of ore by an ordinary guard magnet. Magnetic permeability is below 1.05.

nonmetal
 * A chemical element (as boron, carbon, phosphorus, nitrogen, oxygen, sulfur, chlorine, or argon) that is not classed as a metal because it does not exhibit most of the typical metallic properties. An element that, in general, is characterized chemically by the ability to form anions, acidic oxides and acids, and stable compounds with hydrogen.

nonmetallic
 * a. Of or pertaining to a nonmetal.

b. Said in general of mineral lusters other than metallic luster. CF: submetallic luster. c. An industrial mineral; usually used in the plural.

nonmetallic armor
 * A tough outer covering or cable sheath of rubber, rubber compound, or thermoplastic, designed to protect cable conductors and insulation from abrasion or other damage from external sources.

nonmetallic mineral
 * a. In resource usage, "nonmetallic mineral" refers to the nonmetallic character of the product, not the mineralogy. Thus graphite is a nonmetallic mineral and molybdenite is "metallic" even though the minerals graphite and molybdenite are so similar in appearance that they may be confused in a casual inspection. Examples include: asbestos, barite, cement, feldspar, gem stones, helium, kyanite, perlite, salt, soda ash, and vermiculite, and even extending to mineral fuels. CF: metallic.

b. In mineral usage, the luster of a nonopaque mineral, which transmits light at least through the thinnest edges and in thin section.

nonmetallic minerals
 * Minerals are conveniently divided into metallic and nonmetallic groups, and then arranged in subdivisions according to the elements which form their main constituents. The nonmetallic minerals (carbon, diamond, coals, bitumen, asphalt, boron, sulfur, rock salt, etc.) lack the properties of the metallic minerals such as a bright metallic luster, hardness, density, and good conduction of heat and electricity.

non-metallic minerals
 * Rocks, minerals, and select naturally occurring and synthetic materials of economic value, exclusive of fuel and metallic ore minerals. The select materials include peat, mineral-derived materials such as lime and cement, and synthetic versions of gemstones, abrasives, graphite, and calcite. Generally, non-metallic minerals undergo no chemical or mineralogical alteration for and in their end-uses; are low-price, high-volume commodities such as construction materials; are higher-priced and large-volume commodities that are raw materials in the chemical and agricultural industry; and very high price but very low volume materials such as gemstones. A characteristic of non-metallic minerals is that, in most cases, they maintain their form and physical properties through processing to final end use. See also: industrial minerals.

non-Newtonian flow
 * Flow in which the relationship of the shear stress to the rate of shear strain is nonlinear; i.e., flow of a subsurface in which viscosity is not constant.

nonnitroglycerin explosive
 * Explosive containing TNT instead of nitroglycerin to sensitize ammonium nitrate; a little aluminum powder may also be added to increase power and sensitiveness. Straight TNT-ammonium nitrate explosives usually contain 15% to 18% TNT and 82% to 85% ammonium nitrate. TNT-ammonium nitrate explosives have densities between 1.0 g/cm (super 3) and 1.2 g/cm (super 3) and velocities of detonation between 3,200 m/s and 4,000 m/s. They are reasonably free from noxious fumes. This type of explosive is susceptible to moisture and should be used only in dry conditions unless packed in sealed containers. The main use of non-nitroglycerin explosives is in primary blasting in quarries and opencast mining, although they are used in some underground work, particularly in ironstone mining. The combination of high strength and relatively high velocity of detonation also makes them applicable for secondary blasting by plaster shooting.

nonpareil brick
 * An insulating brick.

nonpermissible explosive
 * An explosive that is not approved in law for use in gassy mines.

nonpolarizable electrode
 * Electrode in which the phenomenon of polarization cannot occur.

nonproductive formation
 * a. A rock unit that, because of its stratigraphic position, is presumed to contain no valuable mineral deposits.

b. A rock unit in which no minerals of interest are found.

nonrotating rope
 * A wire rope composed of 18 strands of 7 wires each; the inner 6 strands are left lay and outer 12 strands are right lay. It is esp. fabricated for use where loads are handled in free suspension, as in lifting of loads with a single line.

nonsegregating chute
 * A chute, usually used to charge stoker hoppers, so designed as to deliver coal in a mixed state rather than having the large lumps tend to be deposited separate from the fine.

nonselective mining
 * The object of nonselective mining is to secure a low cost, generally by using a cheap stoping method combined with large-scale operations. This method can be used in deposits where the individual stringers, bands, or lenses of high-grade ore are so numerous and so irregular in occurrence and separated by such thin lenses of waste that a selective method cannot be employed. Nonselective methods of stoping include caving, top slicing, some forms of open stoping, and shrinkage stoping under most conditions.

nonsequence
 * A diastem or other relatively unimportant sedimentary or stratigraphic interruption. CF: unconformity; paraconformity.

nonsignificant anomaly
 * An anomaly that is superficially similar to a significant anomaly but is unrelated to ore. Formerly called false anomaly.

nonsparking tool
 * Tool, made from beryllium-copper or aluminum-bronze, that produces no sparks, or low energy sparks, when used to strike other objects.

nonspin cable
 * A wire or fiber cable so constructed as to reduce twisting to a minimum.

nonspin differential
 * A differential that will turn both axles, even if one offers no resistance.

nonspinning rope
 * A rope wire consisting of 18 strands of 7 wires each, in 2 layers; the inner layer consists of 6 strands lang lay rope and left lay around a small hemp core, and the outer of 12 strands regular lay, right-hand lay. Will carry a load on a single end without untwisting.

nonstranded rope
 * A rope in which the wires are not laid up in strands but in concentric sheaths, and in opposite directions in the different sheaths, which gives the rope nonspinning properties. The outer sheaths are composed of specially shaped interlocking wires, and there is no hemp core in the rope.

nonstructural
 * A phase transformation not involving structural rearrangement, e.g., Curie point in magnetism.

nontabular deposit
 * A mineral deposit of irregular shape. See also: mass.

nontectonite
 * Any rock whose fabric shows no influence of movement of adjacent grains; e.g., a rock formed by mechanical settling. Some rocks are transitional between a tectonite and a nontectonite.

nontronite
 * A monoclinic mineral, Na (sub 0.33) Fe (super 3+) (sub 2) (Si,Al) (sub 4) O (sub 10) (OH) (sub 2) .nH (sub 2) O ; smectite group; expansive, a swelling clay; earthy; occurs in vesicles and veins in weathered basalt and as an alteration product of volcanic glass. Syn: pinguite. Formerly called chloropal; gramenite; morencite.

nonuniform flow
 * A flow the velocity of which is undergoing a positive or negative change. If the flow is constant it is referred to as uniform flow.

nonvitreous
 * A relative term as applied to ceramic products based on the water absorbing characteristics; i.e., brick, tile, etc., which absorb water in excess of that given by the specifications would be described as nonvitreous. See also: impervious; vitreous; semivitreous.

nonvitrified
 * See: nonvitreous.

nonweathering coal
 * Coal having a weathering index, as defined by U.S. Bureau of Mines standards, of less than 5%.

nonwetted
 * a. A term used in the flotation process and applied to certain metallic minerals that are not wetted with water but are easily wetted with oil.

b. As used by diamond-bit setters, a diamond inset in a metal or alloy that has not adhered to or wetted the surface of the diamond.

Norbide
 * Trade name for boron carbide, an artificial abrasive; chemical formula, BC. It is markedly harder than silicon carbide and second only to diamond.

nordite
 * An orthorhombic mineral, (La,Ce)(Sr,Ca)Na (sub 2) (Na,Mn)(Zn,Mg)Si (sub 6) O (sub 17) ; forms pale brown crystals on the Kola Peninsula, Russia.

norite
 * A coarse-grained plutonic rock containing basic plagioclase (labradorite) as the chief constituent and differing from gabbro by the presence of orthopyroxene (hypersthene) as the dominant mafic mineral. CF: hypersthenite.

norm
 * a. The theoretical mineral composition of a rock expressed in terms of normative mineral molecules that have been determined by specific chemical analyses for the purpose of classification and comparison; the theoretical mineral composition that might be expected had all chemical components crystallized under equilibrium conditions according to certain rules. Adj: normative. See also: normative mineral; norm system. CF: mode.

b. Optimum operating condition of one or more controlled characteristics in a process such as continuous ore treatment.

normal
 * a. Of or pertaining to a solution having a concentration of 1 g-equivalent weight of solute per liter of solution; commonly used term in analytical chemistry. See also: normal solution.

b. Used to designate aliphatic hydrocarbons, their derivatives, or alkyl radicals, the molecules of which contain a single unbranched chain of carbon atoms.

normal air
 * A mixture of dry air and water vapor, varying from 0.1% to 3% by volume (usually over 1% in mines).

normal arc
 * A term specif. intended to differentiate between the arcs that are commonly observed and the low-pressure skittering arcs.

normal calorie
 * The quantity of heat required to raise 1 g of water from 14.5 degrees C to 15.5 degrees C.

normal corrosion
 * When used in connection with galvanic corrosion, it may refer to corrosion of the anodic metal when there is no contact with the dissimilar metal.

normal depth
 * The depth of water in an open conduit that corresponds to uniform velocity for the given flow. It is a hypothetical depth under conditions of steady nonuniform flow, the depth for which the surface and bed are parallel; also termed the neutral depth.

normal dip
 * See: regional dip.

normal displacement
 * See: dip slip.

normal fault
 * A fault in which the hanging wall appears to have moved downward relative to the footwall. The angle of the fault is usually 45 degrees to 90 degrees . There is dip separation, but there may or may not be dip slip. CF: reverse fault; thrust fault. Syn: gravity fault.

normal field
 * as derived from a large-scale survey, worldwide or of continental scope. The normal field of the Earth varies slowly with time, and maps of it are as of a certain date.

normal fold
 * See: symmetrical fold.

normal haul
 * A haul whose cost is included in the cost of excavation, so that no separate charge is made for it.

normalized steel
 * Steel that has been given a normalizing heat treatment intended to bring all of a lot of samples under consideration into the same condition.

normalizing conveyor
 * A conveyor that moves material through a normalizing furnace under heat.

normally consolidated
 * Said of a soil deposit that has never been subjected to an effective pressure greater than the existing overburden pressure and one that is also completely consolidated by the existing overburden.

normal moisture capacity
 * See: field capacity.

normal pressure
 * Usually equal to the weight of a column of mercury 760 mm in height. Approx. 14.7 psi (101.4 kPa). Syn: standard pressure.

normal price
 * As applied to metal prices, it is the average over a long term--sometimes a period greater than the life of a mine. See also: basic price.

normal scale
 * See: effective temperature.

normal shift
 * In a fault, the horizontal component of the shift, measured perpendicular to the strike of the fault. See also: offset; shift.

normal solution
 * A solution made by dissolving 1 g-equivalent weight of a substance in sufficient distilled water to make 1 L of solution. See also: normal.

normal stress
 * The stress component at right angles to a given plane. See also: stress.

normal stress component
 * That component of the stress in a rock mass that acts perpendicular to the lode plane or any other reference plane.

normal temperature
 * a. Normal temperature and pressure are taken as 0 degrees C (273 degrees absolute) and 30 in (760 mm) of mercury pressure. Also called standard temperature.

b. As applied to laboratory observations of the physical characteristics of bituminous materials, it is 77 degrees F (25 degrees C).

normal theory
 * A theory claiming that the removal of a coal seam caused the overlying strata to fracture at right angles to the inclination of the beds. Subsidence observations do not support this theory. See also: dome theory.

normal travel-time curve
 * In fan shooting, a time-distance curve obtained along a profile in some nearby area that does not contain geologic structures of the type being sought.

normative
 * The adj. of norm.

normative mineral
 * A mineral whose presence in a rock is theoretically possible on the basis of certain chemical analyses. A normative mineral may or may not be actually present in the rock. See also: norm. Syn: standard mineral.

norm system
 * A system of classification and nomenclature of igneous rocks based on the norm of each rock. It is used in detailed petrologic studies rather than in ordinary geologic or mining work. Syn: CIPW system. See also: norm.

Norsk-Staal process
 * A process for the direct production of iron sponge. A mixture of carbon monoxide and hydrogen is used as the reducing agent. The equipment consists of three vertical ovens, for preheating, reducing, and cooling the charge, and apparatus for regenerating the spent gases. The ore is contained in a series of muffle trays, each tray holding about 3 tons of ore. These trays pass down through the preheating oven, where the ore is heated to 1,000 degrees C, and are then transferred to the reducing oven, where they are raised through and against the downward gas current, then transferred to the cooling shaft, and slowly lowered down it. The transfer of a tray from one oven to another is made without contact with air. The ore is preheated in the first oven by part of the gases from the reduction oven, and the sponge iron is cooled in the third oven to 50 degrees C by cold gas from a gas holder.

norstrandite
 * A triclinic mineral, Al(OH) (sub 3) ; cryptocrystalline; a constituent of strongly weathered soils, of laterites and bauxites.

north end
 * York. The rise side of the coal in North Yorkshire.

north-seeking pole
 * The end of a magnet that points approx. north. The other end is the south-seeking pole.

Norwalt separator
 * Trade name for a dense-medium washer for treating coal lump size down to about 1/8 in (3.2 mm). It comprises a shallow circular tank with a flat base and a conical inner shell containing the driving mechanism. The clean coal floats and passes over a weir while the shale sinks to the bottom and is conveyed to an outlet chute. Its capacity ranges from about 50 st/h (45.4 t/h) to over 500 st/h (454 t/h), depending on the size of the vessel.

Norwegian cut
 * A variation of the ordinary cut that may be said to represent a combination of the latter and the fan cut. The first drill holes are formed with a sharper angle toward the working face, which facilitates breaking. This type of cut has been employed successfully in headings of small section, the cut hole being blasted first, followed by the bench holes. In order to obtain the maximum possible advance the cut may also be deepened after blasting, during the first pause in working, e.g, the whole section then being broken out simultaneously.

nose
 * a. Scot. A point; a projecting angle of coal or other mineral. Also called ness.

b. The lead face of the crown of a diamond bit. c. A short plunging anticline without closure. d. To dip or run in the form of a geological nose.

nosean
 * An isometric mineral, Na (sub 8) Al (sub 6) Si (sub 6) O (sub 24) (SO (sub 4) ).H (sub 2) O ; sodalite group; occurs in silica- and lime-deficient igneous rocks. Formerly called noselite, nosin, nosite.

nose in
 * Eng. A stratum is said to nose in when it dips beneath the ground into a hillside in a V-form or nose form.

noselite
 * See: nosean.

nose out
 * a. Eng. A nose-shaped stratum cropping out.

b. To diminish by losing stratum after stratum and getting into the lower part of the measure; said of a coal seam.

nose pipe
 * The inside nozzle of a tuyere.

nosin
 * See: nosean.

nosite
 * See: nosean.

notch
 * a. An angular recess cut in the ends of a crossbar of a timber set to fit over a corresponding wedge in the upright posts. With the advent of steel arches, the craft of notching is becoming extinct. See also: Welsh notch.

b. Eng. See: let into. c. A small weir made for use in measuring flow in laboratory models of hydraulic structures. See also: measuring weir. d. A hollow formed by the undermining of a cliff, as a result of wave erosion and/or solution.

notch effect
 * Locally increased stress at that point in a structural load-bearing member where the section changes at a sharp angle.

notcher
 * A machine tool in a steel-fabrication shop used to strip the flanges from the ends of rolled steel joists.

notching
 * a. A method of excavating in a series of steps.

b. Cutting out various shapes from the edge of a strip, blank, or part.

notch sensitivity ratio
 * Alternative term for factor of stress concentration in fatigue or fatigue strength reduction factor.

not previously known to exist
 * These words refer to the time of the location and commencement of the tunnel and not to the respective times of the discoveries of the various veins in the tunnel.

Nottingham system
 * A longwall method of working coal seams in which the trams run on a rail track along the face and are hand loaded at the sides. It follows that the system can be adopted only in relatively thick seams where the trams can travel along the face without any roof ripping. The method is now replaced by face conveyors. Syn: Barry mining.

noumeite
 * See: garnierite.

novackite
 * A monoclinic mineral, (Cu,Ag) (sub 21) As (sub 10) ; pseudotetragonal; forms steel-gray granular aggregates; at Cerny Dul, Czech Republic.

novaculite
 * a. A dense, hard even-textured, light-colored cryptocrystalline siliceous sedimentary rock, similar to chert but characterized by dominance of microcrystalline quartz over chalcedony. It was formerly believed to be the result of primary deposition of silica, but in the type occurrence (Lower Paleozoic of the Ouachita Mountains, Arkansas and Oklahoma) it appears to be a thermally metamorphosed bedded chert, distinguished by characteristic polygonal triple-point texture. The origin of novaculite has also been ascribed to crystallization of opaline skeletal material during diagenesis. The rock is used as a whetstone. See also: Arkansas stone. Syn: razor stone; Turkey stone; ouachita stone.

b. A term used in southern Illinois for an extensive bedded chert. c. A general name formerly used in England for certain argillaceous stones that served as whetstones.

nowel
 * a. The inner part of a large mold, corresponding to the core in small work.

b. The bottom or drag of a molding flask, as distinguished from the cope.

noxious gas
 * A gas that is injurious to health.

nozzle brick
 * A tabular refractory shape used in a ladle, with a hole through which steel is teemed at the bottom of a ladle, the upper end of the shape serving as a seat for the stopper.

nozzleman
 * In metal mining, one who operates a hydraulic giant or monitor (nozzle) used to direct a high-pressure stream of water against a bank of gold-bearing gravel to erode and force the gravel into sluiceboxes, where the gold separates out and is caught by riffles (cleats). Syn: giant tender.

NPN process
 * A modification of the basic Bessemer process. The main feature is the shortening of the blow by increasing the pressure of the blast as much as possible. Normally, the melt is cooled by the addition of scrap or iron ore, but it is claimed that a fairly high temperature can be maintained without an undue increase of the nitrogen content, so that ladle skulls can be avoided.

NQ
 * A letter name specifying the dimensions of bits, core barrels, and drill rods in the N-size and Q-group wireline diamond drilling system having a core diameter of 47.6 mm and a hole diameter of 75.7 mm.

N rod bit
 * A Canadian standard noncoring bit having a set diameter of 2.940 in (74.7 mm). More commonly called a 2-15/16 N drill-rod bit.

N-truss
 * A bridge or roof truss that has parallel upper and lower chords and an arrangement of web members consisting of tension diagonals and compression verticals, with the vertical struts separating the panels. Also known as a Pratt truss. See also: Warren girder.

nubber
 * a. Mid. A block of wood about 12 in (30.5 cm) square, for throwing mine cars off the road in case the couplings or ropes break.

b. See: stopblocks.

nuclear-assisted mining
 * The use of a nuclear explosive for fracturing and fragmenting large volumes of ore underground into rubble chimneys, in preparation for block-cave-type mining or in-situ leaching.

nuclear log
 * See: radioactivity log.

nuclear magnetism log
 * Primarily a hydrogen log, useful for the following purposes: (1) provides valuable correlating curve to replace the S.P. in holes containing oil or invert muds; (2) provides a means of qualitatively distinguishing zones containing hydrocarbons from zones containing only water; (3) provides a means of measuring quantitatively what proportion of the total fluid-filled porosity in a formation is sufficiently free from the influence of chemical binding forces to be considered mobile and thus potentially recoverable; and (4) provides a means of estimating the permeabilities of formations.

nuclear magnetometer
 * See: nuclear resonance magnetometer.

nuclear powerplant
 * Any device, machine, or assembly thereof that converts nuclear energy into some form of useful power, such as mechanical or electric power. In a nuclear electric powerplant, heat produced by a reactor is used to make steam, and the steam drives a turbine generator in the conventional way.

nuclear reaction
 * A reaction involving the nucleus of the atom, such as fission, neutron capture, radioactive decay, or fusion; and distinct from a chemical reaction, which is limited to changes in the electron structure surrounding the nucleus.

nuclear resonance magnetometer
 * An instrument that measures the Earth's magnetic field, depending on the magnetic moment of the atom. Hydrogen atoms are generally used, and these can be in a compound such as water. Each hydrogen atom can be viewed as a tiny electromagnet whose strength and direction are determined by the revolution of the electron of the atom about its nucleus. In a magnetic field, atoms of hydrogen have a tendency to align themselves in opposition to the field. If the direction of the field is suddenly changed, there will be a moment pulling the atoms toward the new direction. But each atom is a midget gyroscope, and instead of shifting directly to the new field direction, it will precess about this direction. The frequency of this precession will be a function only of the strength of the magnetic field. Syn: nuclear magnetometer.

nucleation
 * The beginning of crystal growth at one or more points.

nucleometer
 * A Geiger counter employing 20 Geiger tubes to increase the sampling area and overcome the inefficiency of a 1-tube counter.

nucleon
 * A constituent of the atomic nucleus; i.e., a proton or a neutron.

nucleus
 * The central point about which matter accumulates to form a larger mass, esp. of a growing crystal or pearl. Plural: nuclei.

nuclide
 * Any species of atom that exists for a measurable length of time. A nuclide can be distinguished by its atomic weight, atomic number, and energy state. The term is used synonymously with isotope. A radionuclide is the same as a radioactive nuclide, a radioactive isotope, or a radioisotope.

Nuflex
 * Trade name for a nonrotating rope of 17 X 7 or 34 X 7 strand construction.

nugget
 * A large lump of placer gold or other metal. CF: heavy gold.

nugget effect
 * Anomalously high precious metal assays resulting from the analysis of samples that may not adequately represent the composition of the bulk material tested due to nonuniform distribution of high-grade nuggets in the material to be sampled.

nugget model
 * A constant variance model most often used in combination with one or more other functions when fitting mathematical models to experimental variograms.

nuisance dust
 * Dust with a long history of little adverse effet on the lungs; does not produce significant organic disease or toxic effect when exposures are kept at reasonable levels.

Nujol
 * In flotation, any of a group of nonionizing hydrocarbon oils that act as collector agents by smearing action, giving aerophilic quality to the surface they selectively coat.

Nullagine Series
 * Local name in Western Australia for the formation consisting essentially of pre-Cambrian rocks made up mainly of jasperoid quartzites and dolomite. Crocidolite asbestos occurs in this formation as cross-fiber seams in lodes in stratified ferruginous quartzites and shales with occasional bands of dolomite.

nullah
 * a. A term used in the desert regions of India and Pakistan for a sandy river bed or channel, or a small ravine or gully, that is normally dry except after a heavy rain.

b. The small, intermittent, generally torrential stream that flows through a nullah. Etymol: Hindi nala. See also: wadi; arroyo. Also spelled: nulla; nallah; nalla.

Numidian marble
 * A general name for marbles of cream, yellow, pink, and red color, found in northern Africa. The quarries were worked by the ancient Romans.

Nummulite limestone
 * A thick bed of limestone, of Eocene age, composed mainly of the remains of the foraminifer Nummulites. The formation stretches from the Alps through Iran to China. It is the stone of which the Great Pyramid is built.

Nusse and Grafer PIV/6 drilling machine
 * A rotary machine used for drilling the holes in combustible gases drainage. It is a two-speed, 150- to 250-rpm machine, drill-rod rotation being operated by a 6-hp (4.47-kW) motor. Traversing is done by a 2-hp (1.5-kW) motor, a pinion of which engages a toothed rack that runs the length of the drill frame. A forward drilling thrust of 4 st (3.6 t) is possible. The machine measures 10 ft (3 m) overall and weighs about 1,000 lb (454 kg). With an improved high-speed gearbox, 100 to 130 ft (30 to 40 m) of coal measures strata can be drilled in a shift.

nut coal
 * a. An abbrev. for chestnut coal. Also called nuts.

b. Prepared bituminous coal that passes through 2- to 3-in (5.1- to 7.6-cm) round holes and over 3/4-, 1-, or 1�-in (1.9-, 2.54-, or 3.2-cm) holes, depending on the screening practice. Anthracite, through 1-5/8-in (4.1-cm) and over 3/16-in (4.8-mm) round holes.

nutcracker
 * See: boulder buster.

NW
 * Letter name specifying the dimensions of bits, core barrels, and drill rods in the N-size and W-group wireline diamond drilling system having a core diameter of 54.7 mm and a hole diameter of 75.7 mm. The NW designation has replaced the NX designation.

NX
 * The NX designation for coring bits has been replaced by the NW designation. See also: NW.

nylon
 * A generic term for a group of synthetic fiber-forming polyamides. The polymer is melted, extruded, stretched, and finally processed to turn it into a textile yarn having a very high strength, great powers of energy absorption, and high resistance to abrasion and rotting. Its major uses in mining are as a reinforcement for conveyor belting and ventilation ducting.

nylon belt
 * A rubber belt containing nylon fiber reinforcing. It is stronger than cotton-duck belts of equivalent size and possesses better troughability and fastener holding strength. Nylon belt has the advantage of a long flex life, and the thinner carcass means easier bending.

nystagmus
 * An eye disease suffered by some miners, in which there is a spasmodic oscillatory movement of the eyeballs; in severe cases, the victim finds difficulty in walking straight. Bad lighting is generally believed to be the main cause, and is possibly aggravated by the workers lying on their sides in thin seams. See also: mining disease.