Appendix:Dictionary of Mining, Mineral, and Related Terms/N/1

N

A Diamond Core Drill Manufacturer's Association letter name for a range of diamond drill fittings intended to be used together with the appropriate casing having an inside diameter of 81 mm or somewhat less.

nablock

A rounded mass, as of flint in chalk, or of ironstone in coal.

nacre

The hard, iridescent internal layer of various mollusk shells, having unusual luster and consisting chiefly of calcium carbonate in the form of aragonite deposited as thin tablets normal to the surface of the shell and interleaved with thin sheets of organic matrix. Syn: pearly; mother-of-pearl.

nacreous

Adj. Applied to the luster of certain minerals, usually on crystal faces parallel to a good cleavage, the luster resembling that of pearls.

nacrite

A monoclinic mineral, Al (sub 2) Si (sub 2) O (sub 5) (OH) (sub 4) ; kaolinite-serpentine group; differs from other kandites, such as triclinic kaolinite and monoclinic dickite, in the stacking order of its layers (polytypy); fine-grained, massive; commonly associated with hydrothermal alteration.

nadir

a. The point on the celestial sphere that is directly beneath the observer and directly opposite the zenith.

b. The point on the ground vertically beneath the perspective center of an aerial-camera lens.

nadorite

An orthorhombic mineral, PbSbO (sub 2) Cl ; an uncommon secondary mineral; in resinous to adamantine crystals in some base-metal deposits.

naetig

Industrial diamond having a grain in all directions instead of in regular layers. CF: feinig.

nagyagite

A possibly orthorhombic mineral, Pb (sub 5) Au(Te,Sb) (sub 4) S (sub 5-8); occurs with other tellurides in lamellar, soft, heavy, lead-gray crystals; one perfect cleavage but may form anhedral masses. Syn: black tellurium.

nahcolite

A monoclinic mineral, NaHCO (sub 3) ; forms small, white, highly soluble, prismatic crystals; in nonmarine evaporite deposits; esp. abundant in parts of the Green River lake beds of Colorado.

naif

adj. Said of a gemstone having a true or natural luster when uncut; e.g., of the natural, unpolished faces of a diamond crystal. Also spelled naife.

nail

a. See: shooting needle.

b. A slender piece of metal, one end of which is pointed, the other end having a head, either flattened or rounded. It is a common means of fastening together several pieces of wood or other material by striking the head with a hammer. The term penny as applied to nails refers to the number of pounds per 1,000 nails; e.g., six-penny nail means 6 lb (2.7 kg) per 1,000; three-penny means 3 lb (1.4 kg) per 1,000, etc.

nailhead spar

A composite variety of calcite having the form suggested by the name.

naked

See: bare; blank hole.

name of lode

The name by which a lode is designated in the notice of location, and subsequent addition thereto is immaterial. The same vein or lode may have different names in different mining locations.

nanotesla

See: gamma.

Nansen bottle

An oceanographic water-sampling bottle, made of a metal alloy that is little reactive with seawater, equipped with a rotary valve at each end so that when it is rotated at depth the valves close and lock shut, entrapping a water sample and setting the reversing thermometers. This bottle is named for its designer, Fridtjof Nansen.

nantokite

An isometric mineral, CuCl ; granular, massive; cubic cleavage; adamantine luster; an uncommon secondary mineral in copper deposits.

naphtha

a. An archaic term for liquid petroleum.

b. Designates those hydrocarbons of the lowest boiling point (under 250 degrees C) that are liquid at standard conditions, but easily vaporize and become flammable. They are used as cleaners and solvents.

naphtha gas

Illuminating gas charged with the decomposed vapor of naphtha.

naphthode

Concretion of bituminous limestone rich in carbonaceous matter.

Napierian logarithm

A natural logarithm.

napoleonite

A variety of hornblende.

nappe

a. A sheetlike, allochthonous rock unit, which has moved on a predominantly horizontal surface. The mechanism may be thrust faulting, recumbent folding, or both. The term was first used for the large allochthonous sheets of the western Alps, and it has been adopted into English. The German equivalent, decke, is also sometimes used in English. Etymol: French, cover sheet, tablecloth. Syn: decke. See also: klippe.

b. Belg. See: aquifer.

napthoid

Liquid petroleumlike product found in cavities of igneous rocks and assumed to be a product of thermal distillation of bituminous substances contained in the country rocks.

narrow

a. A roadway driven in the solid coal with rib sides. All roadways when opening out a pillar method of working are narrow. See also: working the whole.

b. N. of Eng. A gallery, or roadway, driven at right angles to a drift, and not quite so large in area.

narrow gage

A railway gage narrower than the standard gage of 4 ft 8-1/2 in (1.44 m).

narrow place

Aust. Working place that is less than 6 yd (5.5 m) wide; these are paid for by the yard in length.

narrow stall

A stall driven in solid coal, usually from 6 to 9 ft (1.8 to 2.7 m) wide; it has rib sides in coal. See also: rib-side; solid road.

narrow work

a. The driving of narrow stalls to form coal pillars as the first stage in the pillar-and-stall method of working.

b. A system of mining in which narrow coal roadways, called endings, are driven along the strike of the seam, from 12 to 15 yd (11.0 to 13.7 m) apart, to a limit line. The long narrow coal pillars between the endings are extracted on the retreat. It has been adopted in parts of Yorkshire and Lancashire, England. See also: endings; main endings. c. All work for which a price per yard of length driven is paid, and which, therefore, must be measured. Any dead work. d. Penn. Headings, chutes, crosscuts, gangways, etc., or the workings previous to the removal of the pillars. e. A working place in coal only a few yards in width.

narrow working

See: bord-and-pillar method; narrow work.

nascent

Just formed by a chemical reaction, and therefore very reactive. Nascent gases are probably in an atomic state.

Nasmyth hammer

A steam hammer, having the head attached to the piston rod, and operated by the direct force of the steam.

Na-spar

See: soda spar.

National coarse thread

The screw thread of common use, formerly known as the United States Standard thread.

National Electrical Code

A set of rules to guide electricians when installing electrical conductors, devices, and machinery.

national grid

Gr. Brit. A system of rectangular coordinates used by the Ordnance Survey and based upon the Transverse Mercator Projection (which is also known as the Gauss Conformal Projection).

national grid coordinates

Gr. Brit. Coordinates, referred to the National Grid of the Ordnance Survey, which are specified in meters and consist of two components, an Easting and a Northing.

Nationalization Act

The Coal Industry Nationalization Act, 1946, which brought all coal mines in the United Kingdom under public ownership. It was passed through Parliament in JuIy 1946 and put into operation on January 1, 1947.

National Physical Laboratory

British government organization that, among other things, tests and certifies calibration of scientific glassware, weights, and measures. Abbrev. NPL.

native

a. Occurring in nature, either pure or uncombined with other substances. Usually applied to metals, such as native mercury, native copper. Also used to describe any mineral occurring in nature in distinction from the corresponding substance formed artificially.

b. Adj. Applied to earth materials occurring in elemental form; e.g., nugget gold, metallic copper. Syn: native element.

native copper

a. Metallic copper, sometimes containing a little silver and bismuth, that occurs as a metasomatic deposit filling cracks and forming the cement of sandstone and conglomerate. Such deposits have been found in the Keweenaw Peninsula, Lake Superior, MI, USA; Chile; Queensland, Australia; and Zimbabwe. Native copper is also found in the upper workings of copper mines.

b. A mineral in the form of particles and nuggets of very pure metallic copper associated (but not alloyed) with small amounts of silver and arsenic minerals. It is found in small amounts in many copper ores but occurs in commerical quantities in only one place in the world, the Upper Peninsula in Michigan. See also: copper.

native element

Element that occurs in nature uncombined, such as nugget gold, metallic copper, etc. See also: native.

native mercury

See: quicksilver.

native nickel-iron

See: awaruite; josephinite.

native water

See: formation water.

natrite

A monoclinic mineral, NaCO (sub 3) ; occurs in very soluble, white, granular masses; a rare mineral in the alkalic complexes of the Kola peninsula, Russia.

natrium

See: sodium.

natrochalcite

A monoclinic mineral, NaCu (sub 2) (SO (sub 4) ) (sub 2) (OH).H (sub 2) O; bright emerald-green; forms steep pyramidal crystals; a secondary copper mineral at Chuquicamata, Chile.

natrojarosite

A trigonal mineral, NaFe (super 3+) (sub 3) (SO (sub 4) ) (sub 2) (OH) (sub 6) ; alunite group; in earthy masses and minute scales; a common alteration product in pyrite-bearing deposits. Formerly called utahite.

natrolite

].16H (sub 2) O ; zeolite group, which may contain appreciable calcium; dimorphous with tetranatrolite; forms acicular to slender prismatic crystals in cavities and veins, esp. in mafic and alkaline igneous rocks. Syn: laubanite.

natromontebrasite

A triclinic mineral, (Na,Li)Al(PO (sub 4) )(OH,F) ; amblygonite group; in granitic pegmatites associated with other lithium minerals. Formerly called fremontite.

natron

A monoclinic mineral, Na (sub 2) CO (sub 3) .10H (sub 2) O ; very soluble; forms earthy or granular crusts and efflorescences; in nonmarine evaporites and on lavas.

natrona

See: sodium sesquicarbonate.

natron granite

Granite abormally high in soda, presumably from the presence of a soda-rich orthoclase or of anorthoclase. It is also called soda granite.

nattle

Eng. To make a slight rattling or tapping noise. Said of a mine when movement or settling is taking place.

natural air crossing

An air crossing in which two airways are separated by rock in its natural state.

natural asphalt

Asphalt before crushing or refining, as mined or quarried in the case of natural rock asphalt, or surface-excavated in the case of lake deposits.

natural carbon

Carbon found in a shape that has not been artificially modified. Also called natural stone.

natural cement

A hydraulic cement produced by pulverizing and then heating naturally occurring rock (cement rock) containing appropriate proportions of limestone, clay, magnesia, and iron. Ignition temperatures are usually lower than for portland cement. Final pulverizing is necessary as with portland cement.

natural coke

Coke made by natural processes, usually by the intrusion of an igneous dike. See also: cinder coal; clinker; coke coal; cokeite.

natural convection

See: convection.

natural diamond

This abrasive is the densest form of crystallized carbon, the hardest substance known. It occurs most commonly as well-developed crystals in volcanic pipes or in alluvial deposits. Bort (boart or borts) sometimes refers to all diamonds not suitable for gems, or it may refer to off-color, flawed, or impure diamonds not fit for use for gems or most other industrial applications, but suitable for the preparation of diamond grain and powder for use in lapping or the manufacture of most diamond grinding wheels. This type of bort is also called crushing bort or fragmented bort.

natural Earth current

Electric current in the Earth not due to human activity.

natural face

A name given to the X direction as pencilled on Z sections of unfaced quartz and whose position is determined by X-ray measurements or etching. The name is also given to the artificial prism face (parallel to 1120) thus located, and produced by sawing the section in the YZ plane. Also applied to the natural growth faces on faced raw quartz crystals.

natural floatability

See: inherent floatability.

natural frequency

The frequency of free oscillation of a system. For a multiple-degree-of-freedom system, the natural frequencies are the frequencies of the normal modes of vibration.

natural frequency of a foundation

The frequency of free vibration of a complete soil-foundation oscillating system. This frequency must differ distinctly from that of any machinery carried by the foundation if resonance is to be avoided.

natural frequency vibrating conveyor

A vibrating conveyor in which the rate of free vibration of the trough on its resilient supports is approx. the same as the rate of vibration induced by the driving mechanism.

natural gamma radiation detector

This is a type of sensor that measures bursts of high-energy electromagnetic waves that are emitted spontaneously by some naturally occurring radioactive elements, such as potassium-40, thorium-232, and uranium-238, that are commonly present in shales and clays.

natural gamma-ray logging

A process whereby gamma rays naturally emitted by formations traversed by a borehole are measured. A tool containing a radiation detector is lowered into the borehole and gamma ray measurements are transmitted to the Earth's surface. The signals are utilized to produce a record of gamma rays detected in correlation with the depth of the detector in the borehole. The record thus obtained in the form of a curve indicating relative number per unit of time of natural gamma rays at different depths, is a conventional natural gamma-ray log, sometimes simply called a gamma-ray log.

natural gas

A mixture of the low-molecular-weight paraffin series hydrocarbons methane, ethane, propane, and butane, with small amounts of higher hydrocarbons; also frequently containing small or large proportions of nitrogen, carbon dioxide, and hydrogen sulfide, and occasionally small proportions of helium. Methane is almost always the major constituent. Natural gas accompanying petroleum always contains appreciable quantities of ethane, propane, butane, as well as some pentane and hexane vapors, and is known as wet gas. Dry gas contains little of these higher hydrocarbons. The exact composition of natural gas varies with locality. The heating value of natural gas is usually over 1,000 Btu/ft (super 3) unless nitrogen or carbon dioxide are important components of the gas. See also: gas; sour gas.

natural glass

A vitreous, amorphous, inorganic substance that has solidified from magma too quickly to crystallize. Granitic or acid natural glass includes pumice and obsidian; an example of a basaltic natural glass is tachylite.

natural logarithm

A logarithm with e as a base.

naturally bonded molding sand

A term used by foundrymen to refer to a sand that, as mined, contains sufficient bonding material for molding purposes.

natural ore

a. In iron mining, the term given to naturally occurring high-grade iron ore; consists of: (1) soft ore, such as porous hematite and limonite (goethite) with minor magnetite and manganese oxides; and (2) hard ores, such as compact, fine-grained, steel-gray hematite, specular hematite, magnetite, or martite. Syn: direct shipping ore.

b. Iron ore that contains moisture, in contrast to "dry ore" that has been dried but not calcined. c. A term used in the U.S. Lake Superior mining district to indicate iron ore formed by natural processes, as distinguished from iron ore products (such as pellets) produced artificially from hard, low-grade ores of the taconite type. Published prices for natural ores from this district usually specify iron content as "natural," meaning that the analysis is based on gross weight including moisture. Syn: lump ore; silicious ore; high-silica ore; wash ore; heavy-media ore; manganiferous ore; natural ore concentrate; lean ore; paint-rock ore; Mesabi non-Bessemer ore.

natural ore concentrate

See: natural ore.

natural paper

Brownish paperlike deposit formed from the filaments of Conferva.

natural resin

See: resin.

natural sand

Sand derived from a rock, in which the grains separate along their natural boundaries. This includes unconsolidated sand or a soft sandstone where little pressure is required to separate the individual grains.

natural scale

Applied to a drawing made to equal vertical and horizontal scales.

natural slope

The maximum angle at which loose material in a bank or spoil heap will stand without slipping. See also: angle of rest; angle of slide.

natural splitting

In mine ventilation, a practice that allows the airflow to divide among the branches of its own accord and without regulation, in inverse relation to the resistance of each airway. CF: controlled splitting.

natural stress relief

The failure of the skin rock of an excavation by crushing, shear, or plastic flow. It can occur on free surface rock with explosive force. See also: arching.

natural ventilating pressure

a. In a mine, air returning from the workings to the surface via the upcast shaft can be of a higher temperature than the air in the downcast shaft because of heat added to the ventilation current from the strata exposed in the mine. Thus, even in a mine with the fan stopped, the upcast air density is less than the downcast air density. This lack of balance in the two vertical air columns produces a pressure difference across the shaft bottom doors known as natural ventilating pressure.

b. The ventilating pressure that produces natural ventilation.

natural ventilation

The ventilation produced in a mine as a result of a difference in density of the air in the upcast and downcast shafts, brought about by natural causes. Natural ventilation is feeble, seasonal, and inconstant.

nauckite

A variety of resin.

naumannite

An orthorhombic mineral, Ag (sub 2) Se ; pseudocubic; black; lustrous; forms heavy, sectile granular masses; also in thin plates; epithermal; a major source of silver in some deposits.

nautical chart

A representation on a horizontal plane, and according to a definite system of projection, of a portion of the navigable waters of the Earth, including the shorelines, the topography of the bottom, and aids and dangers to navigation; it may be derived from hydrographic, topographic, or aerial surveys, or a combination thereof.

nautical measure

One nautical mile or knot equals 6,080.20 ft (1,853.248 m); 3 nmi equal 1 league; and 60 nmi equal 1 degree of longitude (at the equator).

nautical mile

Any of various units of distance, used for sea and air navigation, based on the length of a minute of arc of a great circle of the Earth and differing because the Earth is not a perfect sphere: (1) a British unit that equals 6,080 ft or 1,853.2 m; also called Admiralty mile; (2) a U.S. unit, no longer in official use, that equals 6080.20 ft or 1,853.248 m; and (3) an international unit that equals 6,076.1033 ft or 1,852 m; used officially in the United States since July 1954.

navajoite

A monoclinic mineral, (V,Fe) (sub 10) O (sub 24) .12H (sub 2) O ; rare; weakly radioactive; soft; a fibrous mineral with a silky luster; associated with corvusite, hewettite, tyuyamunite, rauvite, steigerite, and limonite.

Navier's hypothesis

An assumption in the design calculation of beams. It states that the stress at any point due to bending is assumed as being proportional to its distance from the neutral axis.

NCB

The National Coal Board of the United Kingdom.

NCB boring tower

A boring tower developed by the National Coal Board of the United Kingdom to make test drillings for coal from positions off the coast. When drilling is in progress, the tower is resting on the seabed. The base is divided into four airtight sections, which are filled with water when the tower is in position for drilling. The water is pumped out to give buoyancy when the tower is refloated for towing to a new drilling site. The tower is designed to withstand gales of 80 mph (128 km/h) and waves of 30 ft (9.1 m) from crest to trough, and it can be used in any depth of water up to 120 ft (36.6 m). The overall height of the tower is 189 ft (57.6 m), and its total weight is about 570 st (517 t). It has reached over 3,000 ft (915 m) drilling depth with core recovery. The first borehole was put down in the Firth of Forth, Scotland.

NCB recorder

This butane combustible gases recorder has a small flame of burning butane gas, which is controlled to give constant heat output with varying ambient temperature and humidity, and with varying butane gas pressure. The heat output is measured by means of a group of thermocouples in a chimney above the flame. The presence of methane in the atmosphere, which has access to the flame via suitable gauzes, increases the voltage generated by the thermocouples. These changes are recorded on a rotating chart calibrated in percentage methane.

neap tide

In oceanography, a high tide occurring at the moon's first or third quarter, when the sun's tidal influence is working against the moon's, so that the height of the tide is below the maximum in the approximate ratio of 3:8.

nearest neighbor interpolation method

A method of assigning a sample value to a point in space. The value assigned is equal to the value of the spatially nearest sample data point. This method is sometimes used as a computer equivalent of the polygonal method of interpolation.

near-gravity material

A washability term popularly defined as the percentage of material in the raw coal within + or -0.1 of the separating specific gravity.

near-mesh

Near-sized; grains close in cross section to a specified screening mesh, which tend to blind apertures and slow down sizing. Syn: near-mesh material.

near-mesh material

Material approximating in size to the mesh aperture.

neat

Cement slurries containing no aggregate, such as sand or gravel. Syn: neat cement.

neat cement

A slurry composed of any cement and water. Syn: neat cement.

neat lines

The excavation lines of a tunnel within which the rock removed is paid for at the agreed contract rate. See also: overbreak.

nebulite

A type of mixed rock whose fabric is characterized by indistinct, streaky inhomogeneities or schlieren and in which no sharp distinction can be made between the component parts of the fabric. Adj: nebulitic.

neck

a. A lava-filled conduit of an extinct volcano exposed by erosion; also called chimney rock or plug. See also: plug.

b. A pipe of igneous rock crossing bedding planes. c. The narrow entrance to a room next to the entry, or a place where the room has been narrowed on account of poor roof. d. A narrow stretch of land, such as an isthmus or a cape. e. A narrow body of water between two larger bodies; a strait.

needle

a. A piece of copper or brass about 0.5 in (1.3 cm) in diameter and 3 ft or 4 ft (0.9 m to 1.2 m) long, pointed at one end, and turned into a handle at the other, tapering from the handle to the point. It is thrust into a charge of blasting powder in a borehole, and while in this position the borehole is tamped solid, preferably with moist clay. The needle is then withdrawn carefully, leaving a straight passageway through the tamping for the miner's squib to shoot or fire the charge.

b. A timber set on end to close an opening for the control of water; it may be either vertical or inclined; a form of stop plank. c. A small metal rod for making the touchhole in the powder used for blasting. d. A hitch cut in the side rock to receive the end of a timber. e. A needle-shaped or acicular mineral crystal.

needle bearing

An antifriction bearing using very small-diameter rollers between wide faces.

needled

Pocketed, as when face bars are set with the face end of the bar pocketed into the coal adjacent to the roof.

needle instrument

Any surveying instrument controlled by a magnetic needle. See also: compass.

needle ore

a. Iron ore of very high metallic luster, found in small quantities, which may be separated into long, slender filaments resembling needles.

b. See: aikinite.

needles

Elongated crystals, tapering at each end to a fine point, as those typical of martensite.

needle traverse

In a survey with a dial (compass), use of a magnetic needle to read the bearing of lines. Opposite is fast needle traverse or work, and refers to the use of a dial as in traversing with a theodolite, where proximity of iron might deflect the needle. Systems can be combined, using needle readings where iron is absent. Also called swinging needle traverse; loose needle traverse.

negative crystal

a. A birefringent crystal in which the refractive index of the extraordinary ray is less than that of the ordinary ray.

b. A cavity within a crystal bounded by the crystal faces of that crystal. See also: inclusion; three-phase inclusion.

negative element

A large structural feature or portion of the Earth's crust, characterized through a long period of geologic time by frequent and conspicuous downward movement (subsidence, submergence), extensive erosion, or an uplift that is considerably less rapid or less frequent than those of adjacent positive elements.

negative elongation

Lathlike, rodlike, or acicular crystals in which the slow polarized light ray lies across the long direction of the crystal. CF: positive elongation. Syn: length fast.

negative moment

See: hogging moment.

negative rake

a. The orientation of a cutting tool in such a manner that the angle formed by the leading face of the tool and the surface behind the cutting edge is greater than 90 degrees . Syn: drag rake. See also: gouge angle.

b. Describes a tooth face in rotation whose cutting edge lags the surface of the tooth face. CF: rake.

negligence

In a legal sense, a failure upon the part of a mine operator to observe for the protection of the interests of the miner that degree of care, precaution, and vigilance that the circumstances justly demand, whereby the miner suffers injury.

neighborite

An orthorhombic mineral, NaMgF (sub 3) ; insoluble; forms rounded grains or pseudo-octahedral crystals; associated with dolomite and quartz in oil shale within the Green River Formation, UT.

nekton

A biological division made up of all the swimming animals found in the pelagic division.

Nelson Davis separator

A cylindrical dense-medium washer developed in the United States. It uses a magnetite water suspension as medium. The bath resembles a drum in shape, its longitudinal axis being horizontal; within the stationary outer casing there is a rotor divided into compartments. Raw coal is fed near the top of the separator, and separation takes place as the rotor revolves. The machine produces clean coal and shale; the magnetite is recovered. It can handle coal up to 10 in (254 mm) in size, the lower limit being about 1/4 in (6.4 mm). Magnetite consumption runs at about 1/2 lb/st (0.25 kg/t) of feed. See also: Leebar separator.

nelsonite

A rock composed essentially of ilmenite and apatite, with or without rutile. The ratio of ilmenite to apatite varies widely. CF: ilmenitite.

nematoblastic

Pertaining to the texture of a recrystallized rock in which the shape of the grains is threadlike. See also: fibroblastic.

neokerogen

Organic debris deposited among marine sediments and modified by bacterial action in such a way as to form the source material of petroleum, or, under certain conditions, to form the kerogen of oil shales.

neolite

A silky, fibrous, stellated, green, hydrous magnesium-aluminum silicate.

Neolithic

In archaeology, the last division of the Stone Age, characterized by the development of agriculture and the domestication of farm animals. Correlation of relative cultural levels with actual age (and, therefore, with the time-stratigraphic units of geology) varies from region to region. Adj: pertaining to the Neolithic.

neomesselite

See: messelite.

neomineralization

Chemical interchange within a rock whereby its mineral constituents are converted into new mineral species; a type of recrystallization.

neomorphic

Said of the mineral grains of a rock that have been regenerated by zones of secondary growth in crystalline continuity. The new material may have been deposited from solutions or from molten fluids.

neoprene plug closure

The function of the neoprene plug is to provide a completely waterproof seal at the open end of the detonator. Moisture penetration could cause desensitization of the explosive charge in the detonator, and in the case of copper-tubed detonators, moisture could produce a potentially dangerous chemical reaction between the lead azide and the copper.

nepheline

A hexagonal mineral, (Na,K)AlSiO (sub 4) ; feldspathoid group; greasy luster; forms glassy crystals, colorless grains, coarse crystals with prismatic cleavage, or masses without cleavage; occurs in alkalic igneous rocks; an essential constituent of some sodium-rich rocks, e.g., nepheline syenite. Formerly called nephelite; eleolite.

nepheline syenite

A plutonic rock composed essentially of alkali feldspar and nepheline. It may contain an alkali ferromagnesian mineral, such as an amphibole (riebeckite, arfvedsonite, barkevikite) or a pyroxene (acmite or acmite-augite); the intrusive equivalent of phonolite. Sodalite, cancrinite, hauyne, and nosean, in addition to apatite, sphene, and opaque oxides, are common accessories. Rare minerals are also frequent accessories. Syn: foyaite; eleolite syenite; midalkalite.

nephelinite

A fine-grained or porphyritic extrusive or hypabyssal rock, of basaltic character, but primarily composed of nepheline and clinopyroxene, esp. titanaugite, and lacking olivine and feldspar.

nephelinitoid

A nepheline-rich groundmass in an igneous rock; the glassy groundmass in nepheline rocks.

nephelinization

The process of introduction of or replacement by nepheline.

nephelometry

The measurement of the cloudiness of a medium; esp. the determination of the concentration or particle sizes of a suspension by measuring, at more than one angle, the scattering of light transmitted or reflected by the medium. CF: turbidimetry.

nephrite

An exceptionally tough, compact, fine-grained, greenish or bluish variety of amphibole (specif. tremolite or actinolite) constituting the less rare or valuable kind of jade. Syn: kidney stone; greenstone.

neptunian dike

A dike filled by sediment, generally sand, in contrast to a plutonic dike filled by volcanic materials. See also: sand dike.

neptunian theory

See: neptunism.

neptunism

The theory, advocated by A. G. Werner in the 18th century, that the rocks of the Earth's crust all consist of material deposited sequentially from, or crystallized out of, water. Etymol: Neptune, Roman god of waters. CF: plutonism. Syn: neptunian theory.

neptunite

A monoclinic mineral, KNa (sub 2) Li(Fe,Mn) (sub 2) Ti (sub 2) Si (sub 8) O (sub 24) ; forms red to black prismatic crystals; occurs in late stages of reduced, silica-deficient environments; e.g., alkaline igneous rocks and veins in serpentinite. See also: mangan-neptunite.

neritic

Pertaining to the shallow seas; for accumulations of shells, but sometimes for the whole environment of deposition on the continental shelf.

neritic zone

That part of the sea floor extending from the low tide line to a depth of 200 m.

Nernst film

In ion exchange, the diffusion-layer supposed to surround a bead of resin. This static film is reduced, or diffusion through it is accelerated, if agitation of the ambient liquor is increased, if temperature is raised, or if concentration of ions in solution is made greater.

nero-antico

A black marble found in Roman ruins, probably from the Taenarian peninsula, Greece.

nesquehonite

An orthorhombic mineral, Mg(HCO (sub 3) )(OH).2H (sub 2) O ; forms low-temperature efflorescences, particularly as an alteration product of lansfordite. Named for a coal mine at Nesquehoning, PA.

ness

A British term used esp. in Scotland for a promontory, headland, or cape, or any point or projection of the land into the sea; commonly used as a suffix to a place name, e.g., Fifeness. Also called nose.

nest

a. A concentration of some relatively conspicuous element of a geologic feature, such as a nest of inclusions in an igneous rock or a small, pocketlike mass of ore or mineral within another formation.

b. A fitting of the next-smaller-size casing inside the casing already set in a borehole, or of one tube inside another.

nested variogram model

A model that is the sum of two or more component models, such as nugget, spherical, etc. Adding a nugget component to one of the other models is the most common nested model, but more complex combinations are occasionally used.

net

a. Scot. Strapping used for lowering or raising horses in shafts.

b. A plane of points each with identical point surroundings. CF: space lattice; lattice.

net calorific value

The heat produced by combustion of unit quantity of a solid or liquid fuel when burned, at a constant pressure of 1 atm (0.1 MPa), under conditions such that all the water in the products remains in the form of vapor. Net heat of combustion at constant pressure is expressed as Q (sub p) (net).

net-corrected fill

Net fill after making allowance for shrinkage during compaction.

net drilling time

The amount of excavated material to be removed from a road section, after completing fills in that section. �@ A�U ��U �<� � � e DICTIONARY TERMS:net drilling time The rotating time actually spent The rotating time actually spent in deepening a borehole.

net fill

The fill required, less the cut required, at a particular station or part of a road.

nether

The lower part of, as in nether roof; opposite of the term "upper."

nether roof

a. The strata directly over a coal seam. The props set at the face hold only the nether roof. E.g., if the props carry a load of 20 st (18.1 mt) each and are set 4 ft (1.2 m) apart each way, the supported weight is 1.5 st/ft (super 2) (14.6 t/m (super 2) ). See also: underweight; absolute roof; overarching weight; immediate roof.

b. In mine subsidence, the immediate roof of limited depth, such as timber might be expected to support.

nether strata

The roof and strata immediately above the coal.

net slip

On a fault, the distance between two formerly adjacent points on either side of the fault, measured on the fault surface or parallel to it. It defines both the direction and relative amount of displacement.

net texture

See: network structure.

Nettleton method

An indirect means of density determination in which a closely spaced gravity traverse is run over some topographic feature, such as a small hill or valley. When the profile of observed values is plotted, the gravitational effect of the feature itself is calculated at each observation point along the profile and removed from the observed value for that point. The calculation is repeated a number of times, different densities being assumed for each computation. The density value at which the hill is least conspicuous on the gravity profile is considered to be most nearly correct.

net unit value

The difference between the gross unit recoverable value and the cost of mining, treating, and marketing ore; in other words, the net operating profit. See also: gross recoverable value; gross unit value.

network

a. Esp. in surveying and gravity prospecting, a pattern or configuration of stations, often so arranged as to provide a check on the consistency of the measured values.

b. In ventilation surveys, the multiple development openings, haulage ways, and working faces that constitute the ventilation system of a mine.

network deposit

See: stockwork.

network structure

A structure in which one constituent occurs primarily at the grain boundaries, thus partially or completely enveloping the grains of the other constituent. Syn: net texture.

Neuenburg saw

A plow consisting of a 2-in (5.1-cm) steel plate 6 ft by 20 in (1.8 m by 50.8 cm) of seven pieces hinged together to follow floor rolls; picks on the face edge cut in both directions. The minimum workable seam is 14 in (35.6 cm) on gradients of 35 degrees to 70 degrees . Maximum face length is 80 yd (73.2 m). The machine is used in the Ruhr.

neuk

The tailgate corner of a face behind the face conveyor tension end.

Neumann lamellae

Straight, narrow bands parallel to the crystallographic planes in the crystals of metals that have been subjected to deformation by sudden impact. They are actually narrow twin band, and are most frequently observed in iron.

neuropteris

A large tree-fern of the coal forest, with trunks about 2 ft (0.6 m) thick, containing several cylinders of wood inside the stem instead of one column of wood as in modern trees.

neutral atmosphere

Atmosphere in which there is neither an excess nor a deficiency of oxygen.

neutral axis

The line of zero fiber stress in any given section of a member subject to bending; it is the line formed by the intersection of the neutral surface and the section.

neutral equilibrium

A body is said to be in neutral equilibrium if on being slightly displaced it remains in its new position; e.g., a ball placed on a horizontal surface or a cone supported on its side on a horizontal surface.

neutralize

To add either an acid or alkali to a solution until it is neither acid nor alkaline.

neutral lining

Furnace lining of neutral refractories.

neutral point

a. A neutral point in a wye-connected alternating-current power system means the connection point of transformer or generator windings from which the voltage to ground is nominally zero, and which is the point generally used for system grounding.

b. In titration, the point at which hydrogen ions and hydroxyls are approx. balanced, each at about 1 times 10 (super -7) molar. Since color-change-indicating dyes do not all react at this point, selection for a given titration must be made with regard to the required point of change.

neutral pressure

The hydrostatic pressure of the water in the pore space of a soil. See also: pore-water pressure; pore pressure; neutral stress.

neutral refractory

a. A refractory that is neither strongly basic nor strongly acid, such as chrome, mullite, or carbon.

b. A refractory that is resistant to chemical attack by both acid and basic slags, refractories, or fluxes at high temperatures.

neutral salt

A salt in which all the hydrogen of the hydroxyl groups of an acid is replaced by a metal.

neutral salt effect

Reduction of ionization of a weak acid or base by addition of ionizing salt that contains one of the ions already present; form of common ion effect.

neutral stress

The stress transmitted by the fluid that fills the voids between particles of a soil or rock mass; e.g., that part of the total normal stress in a saturated soil caused by the presence of interstitial water. Syn: pore pressure; pore-water pressure; neutral pressure.

neutral surface

The longitudinal surface of zero fiber stress in a member subject to bending; it contains the neutral axis of every section.

neutral zone

A strain-free area. CF: compression zone; tension zone.

neutron

An uncharged elementary particle with a mass that nearly equals that of the proton. An isolated neutron is unstable and decays with a half-life of about 13 min into an electron, a proton, and a neutrino. Neutrons sustain the fission chain reaction in a nuclear reactor.

neutron density

The number of neutrons per cubic centimeter.

neutron-gamma log

A radioactivity log employing both gamma and neutron-log curves. The neutron log should respond best to porous fluid-filled rock and the gamma best to shale markers.

neutron log

Strip recording of the secondary radioactivity arising from the bombardment of the rocks around a borehole by neutrons from a source being caused to move through the borehole. Used, generally in conjunction with other types of logs, for the identification of the fluid-bearing zones of rocks. See also: radioactivity log; neutron logging.

neutron logging

A radioactivity logging method used in boreholes in which a neutron source provides neutrons that enter rock formations and induce additional gamma radiation, which is measured by use of an ionization chamber. The gamma radiation so induced is related to the hydrogen content of the rock.

Nevadan orogeny

Late Jurassic-Early Cretaceous diastrophism in Western North America.

nevyanskite

A former name for iridosmine. See also: iridosmine.

Newark Supergroup

Continental strata of Lower Jurassic or Upper Triassic age in the Eastern United States, consisting essentially of red sandstone, shale, arkose, and conglomerate, some 14,000 to 18,000 ft (4.3 to 5.5 km) thick. The series includes black shales with fish remains, thin coal seams in Virginia and North Carolina, and basaltic flows and sills.

Newaygo screen

A slanting screen in which the material to be screened passes down. The screen is kept in vibration by the impact of a large number of small hammers.

newjersite

Variety of resin.

Newlyn datum

The mean sea level now used as the British Ordnance Datum for leveling. It was determined as the result of several years' observations at Newlyn, Cornwall, England, and differs at various places by more than 0.3 m from levels based on the Liverpool datum, which it supersedes.

Newmann hearth

A modified Scotch hearth in which poking or rabbling is done mechanically.

new miner training

In mining, mandatory training given the miners having no previous mining experience; includes instruction in the statutory rights of miners and their representatives, use of self-rescue devices and respiratory devices where appropriate, hazard recognition, emergency procedures, electrical hazards, first aid, walk around training, and other health and safety aspects of the tasks to which the person will be assigned. CF: refresher training; task training.

new sand

Newly mixed, but not unused, molders' sand.

new scrap

The material generated in the manufacturing process of articles for ultimate consumption; it includes defective castings, clippings, turnings, borings, drosses, slags, etc., that are returned directly to the manufacturing process or sold directly for reprocessing.

Newtonian fluid

Term marking the distinction, made in mineral processing that involves agitation, between a truly viscous (Newtonian) liquid and one in which shear or apparent viscosity (pseudoviscosity) varies with the dimensions of the containing system and the speed of agitation. The latter type of fluid is said to be non-Newtonian.

Newton's law of gravitation

See: law of gravitation.

New York rod

A leveling rod marked with narrow lines, ruler fashion.

N-frame brace

A diagonal brace in a square set.

ngavite

A chondritic stony meteorite composed of bronzite and olivine in a friable, breccialike mass of chondrules.

niccolite

A former name for nickeline. Also spelled nicolite. Syn: arsenical nickel; copper nickel.

Nicholls' technique

A technique used in the determination of elastic constants of rock in situ. Longitudinal and shear waves are generated in rock by small explosive charges in shallow drill holes. Accelerometers and strain gages are employed to measure arrival times for both waves. From wave velocities and measured density, Poisson's ratio, modulus of elasticity, modulus of rigidity, Lame's constant, and bulk modulus can be calculated.

nickel

a. An isometric mineral, elemental Ni; hard; metallic; silver-white; a native metal, esp. in meteorites; also alloyed with iron in meteorites.

b. A silvery white, hard, malleable, ductile, somewhat ferromagnetic element. Symbol: Ni. It takes on a high polish and is a fair conductor of heat and electricity. Used for making stainless steel and other corrosion-resistant metals and is chiefly valuable for the alloys it forms. Also used extensively in coinage, in desalination plants for converting sea water into fresh water, and in making nickel steel for armor plate and burglar-proof vaults.

nickel antimony glance

Sulfantimonide of nickel, crystallizing in the cubic system. Also called ullmannite.

nickel bloom

A green hydrated and oxidized patina on rock outcrops indicating the existence of primary nickel minerals; specif. annabergite (a nickel arsenate). The term is also applied to zaratite (a nickel carbonate) and to morenosite (a nickel sulfate). See also: annabergite.

nickel carbonyl

A volatile compound of nickel, Ni(CO) (sub 4) , formed by passing carbon monoxide over the heated metal. The compound is decomposed into nickel and carbon monoxide by further heating. It is used on a large scale in industry for the production of nickel from its ores by the Mond process.

nickel glance

See: gersdorffite.

nickel green

See: annabergite.

nickeliferous

Containing nickel.

nickeline

a. A hexagonal mineral, 2 ; commonly contains antimony, cobalt, iron, and sulfur; one of the chief ores of nickel. Formerly called: niccolite; nickelite; arsenical nickel; copper nickel; kupfernickel.

b. The mineral group breithauptite, freboldite, imgreite, langisite, nickeline, sederholmite, sobolevskite, stempflite, and sudburyite.

nickel iron

a. A mineral, NiFe, containing about 76% nickel and found in meteorites. Isometric.

b. The native alloy of nickel with iron in meteorites. See also: kamacite; taenite.

nickelite

A former name for nickeline. See also: nickeline.

nickel ocher

An early name for annabergite.

nickelous oxide

a. NiO; green, becoming yellow. Found in nature as the mineral bunsenite. Soluble in acids and in ammonium hydroxide; insoluble in water; sp gr, 6.6 to 6.8. NiO absorbs oxygen at 400 degrees C forming Ni (sub 2) O (sub 3) which is reduced to NiO at 600 degrees C. Used in nickel salts and in porcelain painting.

b. Isometric; green to black; molecular weight, 74.71; melting point, 1,990 degrees C; sp gr, 6.67. Used for painting on china.

nickel oxide

Comprises the two nickel oxides, nickelous oxide (NiO) and nickelic oxide (Ni (sub 2) O (sub 3) ) , which are used extensively as colorants in glasses, glazes, and enamels. The use of nickel oxide in enamels is generally in the ground coat, in which it is used with cobalt and manganese. It is also used in cover coat enamels to give what is known as a daylight shade for reflector units. Nickelic oxide imparts a color to glass which is dependent upon the character of the alkali present. Nickelous oxide is used in glazes to produce blues, greens, browns, and yellows. Nickel oxide is also one of the principal components of certain type of ferrites, e.g, the nickel-zinc ferrite. See also: nickelous oxide.

nickel plating

The deposition of a coating of metallic nickel by electrolysis.

nickel pyrite

See: millerite.

nickel-skutterudite

An isometric mineral, NiAs (sub 2-3) ; isostructural with skutterudite; tin white; in intermediate-temperature hydrothermal veins, particularly in association with Co, Ni, Fe arsenides, sulfarsenides, and native silver. Syn: white nickel.

nickel vitriol

See: morenosite.

nicking

a. The cutting of a vertical groove in a seam to liberate coal after it has been holed or undercut.

b. Used in wire-rope terminology to describe the internal crosscutting of wires within a rope. c. The chipping of coal along the rib of an entry or room, which is usually the first indication of a squeeze. d. A vertical cutting or shearing one side of a face of coal. Also called cut; cutting.

nickings

Newc. The small coal produced in making a nicking. See also: bug dust; makings.

nicol

a. Nicol prism.

b. Any apparatus that produces polarized light, e.g., Nicol prism or Polaroid. See also: polar; polarizer.

nicolite

A former name for nickeline. See also: nickeline.

Nicol prism

A special prism for producing polarized light, made from two pieces of Iceland spar (calcite) cemented together with Canada balsam. Light entering the prism is split into two polarized rays; of these, the ordinary ray is totally reflected at the balsam layer while the extraordinary ray is able to pass through the prism. In a petrological microscope two Nicol prisms are incorporated. See also: polarizing prism.

Niggli's classification

a. A classification of igneous rocks on the basis of their chemical composition, similar in some respects to the norm system. It was proposed in 1920 by the Swiss mineralogist Paul Niggli.

b. A classification of ore deposits, the major groups being plutonic, or intrusive, and volcanic, or extrusive. It was proposed in 1929.

night emerald

See: evening emerald.

night pair

Corn. Miners who work underground during the night. The night shift.

night shift

The coal miners' shift from about 12:00 p.m. to 8:00 a.m. It may be a coal-winning shift, but in general it is a preparation or maintenance shift.

nigritite

A product of the coalification of fix bitumens rich in carbon; insoluble or only slightly soluble in organic solvents. It is subdivided into polynigritite, humonigritite, exinonigritite, and keronigritite.

nil

Nothing; zero. Often used in reporting gold and silver assays.

nine-inch straight

A standard 9-in by 4-1/2-in by 2-1/2-in (22.9-cm by 11.4-cm by 6.4-cm) straight brick.

nine-point sample

Final sample taken for test when a small quantity of finely ground mineral is required for assay. A suitable quantity of dry material is thoroughly mixed on glazed cloth or paper, if necessary, being rolled lightly with a round bottle to break down any floccules. It is then flattened to a disk and eight equal segments are marked out diametrically with a spatula. Approx. equal quantities are taken from each segment and from the center, making the nine points of withdrawal.

ningyoite

An orthorhombic mineral, (U,Ca,Ce) (sub 2) (PO (sub 4) ) (sub 2) .1-2H (sub 2) O ; rhabdophane group; occurs in an unoxidized zone of the Ningyo-toge Mine, Tottori prefecture, Japan.

niobite

See: columbite.

niobium

A shiny, white, soft, and ductile metallic element. Symbol, Nb (niobium) or Cb (columbium). The name niobium was adopted by the International Union of Pure and Applied Chemistry. Many chemical societies and government organizations refer to it as niobium, but most metallurgists, metals societies, and commercial producers still refer to the metal as columbium. Found in niobite (or columbite), niobite-tantalite, pyrochlore, and euxenite. Used as an alloying agent in carbon and alloy steels, in nonferrous metals, and in superconductive magnets. Syn: columbium.

niobium boride

One of several compounds that have been reported, including the following: NbB (sub 2) ; melting point, 3,050 degrees C; sp gr, 7.0; thermal expansion, 5.9 X 10 (super -6) parallel to a and 8.4 X 10 (super -6) parallel to c; NbB, melting point, 2,300 degrees C; sp gr, 7.6; Nb (sub 3) B (sub 4) melts incongruently at 2,700 degrees C; sp gr, 7.3.

niobium nitride

One of three nitrides that have been reported: NbN, Nb (sub 2) N , and Nb (sub 4) N (sub 3) . During reaction between niobium and N (sub 2) at 800 to 1,500 degrees C the product generally consists of more than one compound. Most of the phases are stable at least to 1,500 degrees C.

nip

a. Where the roof and the floor of a coal seam come close together pinching the coal between them. CF: want.

b. The contact ends of a cable for quick attachment to a power cable. c. The device at the end of the trailing cable of a mining machine used for connecting the trailing cable to the trolley wire and ground. d. To move a machine along a track by sliding the nip along the trolley wire. e. The seizing of material between the jaws or rolls of a crusher. f. See: angle of nip. g. To cut grooves at the end of a bar, to make it fit more evenly. h. An undercutting notch in rock, particularly limestone, along a seacoast between high- and low-tide levels produced by erosion or possible solution.

niperyth

See: penthrite.

nipple

A tubular pipe fitting usually threaded on both ends and under 12 in (30.5 cm) in length. Longer pipe is regarded as cut pipe. See also: close nipple.

Ni-resist

A cast iron consisting of graphite in a matrix of austenite. It contains 3.0% carbon, 14.0% nickel, 6.0% copper, 2.0% chromium, and 1.5% silicon; it has a high resistance to growth, oxidation, and corrosion.

nital

See: Boylston's reagent.

niter

An orthorhombic mineral, 4 ; water soluble; has a cooling salty taste; a product of nitrification in most arable soils in hot, dry regions, and in the loose earth forming the floors of some natural caves. CF: nitratine. Syn: saltpeter. Also spelled nitre.

niter cake

Crude sodium sulfate, a byproduct in the manufacture of nitric acid from sodium nitrate.

nitrate

a. A salt of nitric acid; e.g., silver nitrate or barium nitrate.

b. A mineral compound characterized by a fundamental anionic structure of NO (sub 3) (super -) . Soda niter, NaNO (sub 3) , and niter, KNO (sub 3) , are nitrates. CF: carbonate; borate. c. Salts formed by the action of nitric acid on metallic oxides, hydroxides, and carbonates. Readily soluble in water and decompose when heated. The nitrates of polyhydric alcohols and the alkyl radicals explode violently.

nitratine

A trigonal mineral, NaNO (sub 3) ; rhombohedral cleavage; water soluble with a cooling taste; occurs only in very arid regions. Formerly called soda niter.

nitrification

The formation of nitrates by the oxidation of ammonium salts to nitrites (usually by bacteria) followed by oxidation of nitrites to nitrates. It is one of the processes of soil formation.

nitro

An abbrev. for nitroglycerin or dynamite.

nitrocalcite

A monoclinic mineral, Ca(NO (sub 3) ) (sub 2) .4H (sub 2) O ; water soluble; soft; occurs as an efflorescence, e.g., on walls and in limestone caves. Syn: wall saltpeter.

nitrocellulose

Nitric acid esters of cellulose formed by the action of a mixture of nitric and sulfuric acids on cellulose. The cellulose can be nitrated to a varying extent, ranging from two to six nitrate groups in the molecule. Nitrocellulose having a low nitrogen content, up to the tetranitrate, is not explosive. They dissolve in ether-alcohol mixtures and in so-called lacquer solvents, such as butyl acetate. A nitrocellulose having a high nitrogen content is guncotton, an explosive. The principal nitrocellulose plastic is celluloid. Syn: cellulose nitrate.

nitrocotton

A chemical combination of ordinary cotton fiber with nitric acid. It is explosive, highly inflammable, and in certain degrees of nitration, soluble in nitroglycerin.

nitrogelatin

See: gelatin dynamite.

nitrogen

Colorless, tasteless, odorless, relatively inert element. Symbol, N. Nitrogen makes up 78% of the air, by volume. From this inexhaustible source it can be obtained by liquefaction and fractional distillation. Used in the production of ammonia and nitric acid, as a blanketing medium in the electronics industry, as a refrigerant, in annealing stainless steel, in drugs, and for forcing crude oil from oil wells.

nitrogen fixation

a. Extracting nitrogen from the air in commercial quantities for use in agriculture or industry.

b. In a soil, the conversion of atmospheric nitrogen to a combined form by the metabolic processes of some algae, bacteria, and actinomycetes.

nitroglycerin

CH (sub 2) NO (sub 3) CHNO (sub 3) CH (sub 2) NO (sub 3) ; pale yellow; flammable; explosive; thick liquid; soluble in alcohol; soluble in ether in all proportions; slightly soluble in water; melting point, 13.1 degrees C; and explosion point, 256 degrees C. Used as an explosive, in the production of dynamite and other explosives, as an explosive plasticizer in solid rocket propellants, and as a possible liquid rocket propellant. Molecular weight, 227.09; triclinic or orthorhombic when solid; sp gr, 1.5918 (at 25 degrees C, referred to water at 4 degrees C); soluble in methanol and in carbon disulfide; very soluble in chloroform; and slightly soluble in petroleum ether. This highly explosive liquid is made by mixing sulfuric acid and nitric acid in a steel tank and then adding glycerin. Its great shattering effect has made it esp. suitable for shooting oil wells. Because of its sensitiveness to shock, liquid nitroglygerin is dangerous to transport and unsuitable for use in mining and quarrying operations. Syn: glycerol trinitrate; trinitrate glycerol; trinitrin; explosive oil.

nitroglycerin explosive

An explosive containing, principally, nitroglycerin, nitrocotton, and inorganic nitrates, with a suitable combustible absorbent giving a balanced composition.

nitroglycerin powder

Explosive usually characterized by a low nitroglycerin content, up to 10% , and a high ammonium nitrate content of 80% to 85%, with carbonaceous material forming the remainder of the composition. This composition produces a powdery consistency and, consequently, nitroglycerin powders have relatively poor water-resistance properties, so that they should be used only in dry conditions. Their storage properties are fairly good, but this is largely dependent on the protection given after manufacture, for example, in the methods of cartridging and packing. The main application of these explosives is in quarrying and mining where the ground to be blasted is relatively soft.

nitrohydrochloric acid

See: aqua regia.

nitrolite

An excellent and cheap explosive in powder form, consisting of the constituents ammonium nitrate + trotyl + nitroglycerin + silicon.

nitromagnesite

A monoclinic mineral, Mg(NO (sub 3) ) (sub 2) .6H (sub 2) O ; water soluble; white; an efflorescence in limestone caverns.

nitromuriatic acid

See: aqua regia.

nitrostarch explosive

Nitrostarch explosives have been used to a limited extent for over 50 years. When these explosives were first introduced, nitrostarch was the principal explosive ingredient in their composition. Of recent years, because of the trend toward the low-sensitivity, noncap sensitive nitrocarbonitrates and ammonium nitrate-oil mixtures, certain grades of explosives are being produced with low amounts of sensitizers. Some of these explosives today contain a very large percentage of ammonium nitrate, and nitrostarch is used only in small quantities to act as a sensitizer.

nitrosubstitution

The act or process of introducing by substitution the nitryl radical, NO (sub 2) , in place of one or more replaceable hydrogen atoms, such as in an organic compound. Nitrosubstitution compounds are used in the manufacture of some explosives.

nitrosulfuric acid

An exceedingly corrosive mixture of one part by weight of nitric acid and two parts by weight of sulfuric acid. Used in the manufacture of nitroglycerin.

nitrous oxide

A gas with the chemical formula, N (sub 2) O ; molecular weight, 46; sp gr, 1.6. This gas is produced by the blasting of certain nitroglycerine explosives, esp. if there is incomplete detonation. It is also produced in the exhaust of diesel locomotives. It is used as an anesthetic in dentistry and is commonly known as laughing gas.

niveau surface

See: equipotential surface.