Appendix:Dictionary of Mining, Mineral, and Related Terms/S/6

sial
 * a. A layer of rocks, underlying all continents, that ranges from granitic at the top to gabbroic at the base. The thickness is variously placed at 30 to 35 km. The name derives from the principal ingredients, silica and alumina. Specific gravity, about 2.7.

b. A petrologic name for the upper layer of the Earth's crust, composed of rocks that are rich in silica and alumina; it may be the source of granitic magma. It is characteristic of the upper continental crust. Etymol: an acronym for silica + alumina. Adj: sialic. CF: sialma. Syn: sal; granitic layer.

siallite
 * a. A group name for the kaolin clay minerals and allophane.

b. A rock composed of siallite minerals.

sialma
 * A mnemonic term derived from (si) for silica, (al) for alumina, and (ma) for magnesium, applied as a compositional term to a layer within the Earth that occupies a position intermediate between sial and sima.

Siam ruby
 * A name sometimes erroneously applied to the dark ruby spinel occurring with the rubies of Thailand.

Siberian aquamarine
 * A blue-green beryl from Siberia, Russia.

Siberian ruby
 * Rubellite; a pink variety of elbaite found in Siberia.

siberite
 * A violet-red or purple variety of elbaite from Siberia. See also: Siberian ruby.

Sicilian amber
 * Simetite, a variety of amber.

sickening
 * a. A scum that forms on the surface of mercury that retards amalgamating, caused by grease, sulfides, arsenides, etc.

b. The flouring of mercury. See also: floured.

sicklerite
 * An orthorhombic mineral, Li(Mn,Fe)PO (sub 4) forms a series with ferrisicklerite; dark brown. Syn: manganese sicklerite.

sick mercury
 * Mercury that has become contaminated so that it has neither a clean, bright surface nor a spheroidal shape when in globules. Effect produced by sulfur, oil, talc, graphite, sulfides of antimony, arsenic or bismuth, calcium earths. In this state, it cannot be used to amalgamate gold.

side
 * a. The more or less vertical face or wall of coal or goaf forming one side of an underground working place.

b. The wall of a vein. c. Part of a rock mass bordering on a fault plane.

side adit
 * A side passage sometimes made when the main adit is choked with waste rock.

side arch pups
 * Firebricks of a certain standard size.

side basse
 * A transverse direction of the line of dip in strata.

sideboard
 * a. A board used in timbering the sides of a heading. See also: side trees.

b. A board applied to the sides of conveyors, usually of the chain type, to increase the height when coal is being loaded at the face by hand onto the conveyor. Also applied to a baffle plate used with belt conveyors.

side-boom dredge
 * Similar to the hopper dredge except that the discharge, instead of going into hoppers or directly back into the sea, is carried in a discharge pipe hung from a boom, a distance of from 200 to 500 ft (60 to 150 m) directly to port or starboard of the vessel, and there discharged into the atmosphere, dropping vertically from a height of about 50 ft (15 m) onto the surface of the sea. The drag heads of the dredge provide a channel, and the excavated soil is spread over a wide shoal area on either side, without the necessity of hauling it to the sea.

sidecasting
 * Piling spoil alongside the excavation from which it is taken.

side-discharge shovel
 * A shovel loader, driven by compressed air or by electricity, for loading loose coal or rock. A bucket of capacity 21 ft (super 3) (0.59 m (super 3) ), hinged to the chassis, digs, lifts, and discharges the material sideways onto a scraper or belt conveyor; suitable for stable holes, pillar methods of working, and general repair work.

side-entrance manhole
 * A deep manhole in which the access shaft is built to one side of the inspection chamber.

side-fired furnace
 * A furnace with fuel supplied from the side.

sidehill cut
 * A long excavation in a slope that has a bank on one side, and is near original grade on the other.

side-hitching
 * An act in which a mule is hooked by its harness to the side instead of the front of a loaded car to give it enough momentum to slide onto a cage.

side-laning
 * S. Staff. The widening of an abandoned gate road, and making it part of the new side of work.

sideline
 * a. The line connecting the dredger with anchorage on either side and winch on board used to steady the hull in required digging position. See also: headline.

b. A surface line of the claim along the vein. It bounds the side of the claim.

sideline agreement
 * In a mineral claim where the apex law applies (United States), neighboring mine owners may come to a sideline agreement to adjust or limit the law as it affects their respective properties.

sidelong reef
 * An overhanging wall of rock in alluvial formation extending parallel with the course of the gutter; generally only on one side of it.

side piles
 * The side poling boards used in driving a heading.

sideplate
 * In timbering, where both a cap and a sill are used, and the posts act as spreaders, the cap and the sill are spoken of as the sideplates. See also: endplate; wallplate.

side-port furnace
 * A furnace with ports on the sides.

siderite
 * a. A trigonal mineral, FeCo (sub 3) ; calcite group, with Fe replaced by Mg toward magnesite and Mn toward rhodochrosite; rhombohedral crystals and cleavage; light to dark brown; in bedded deposits (black-band ores, clay ironstone); occurs in hydrothermal veins, cavities in mafic igneous rocks, pegmatites, and limestone; a source of iron. Syn: chalybite; spathic iron; sparry iron; rhombohedral iron ore; iron spar; junckerite; junkerite; siderose; white iron ore. See also: iron ore.

b. An obsolete syn. of sapphire quartz. See also: sapphire quartz. c. An obsolete term formerly applied to various minerals, such as hornblende, pharmacosiderite, and lazulite. d. A general name for iron meteorites, composed almost wholly of iron alloyed with nickel. Obsolete syn: aerosiderite.

siderodot
 * A variety of siderite containing calcium.

sideroferrite
 * A variety of native iron occurring as grains in petrified wood.

siderogel
 * Amorphous FeO(OH) in some bog iron ores.

sideromelane
 * A basaltic glass from the palagonite tuffs of Sicily, Italy.

sideronatrite
 * An orthorhombic mineral, Na (sub 2) Fe(SO (sub 4) ) (sub 2) (OH).3H (sub 2) O ; soft; orange to straw-yellow.

siderophile
 * a. Said of an element concentrated in the metallic rather than in the silicate and sulfide phases of meteorites, and probably concentrated in the Earth's core relative to the mantle and crust (in Goldschmidt's scheme of element partition in the solid Earth).

b. Said of an element with a weak affinity for oxygen and sulfur, and readily soluble in molten iron. Examples are Fe, Ni, Co, P, Pt, Au. CF: lithophile.

siderophyllite
 * A monoclinic mineral, KFe (sub 2) Al(Al (sub 2) Si (sub 2) )O (sub 10) (F,OH) (sub 2) ; mica group.

siderosa
 * Sp. Spathic iron ore or siderite.

sideroscope
 * An instrument for detecting small quantities of iron by the magnetic needle.

siderose
 * See: siderite.

siderosis
 * Pneumoconiosis occurring in iron workers from inhalation of particles of iron.

siderosphere
 * See: inner core.

sidertil
 * A triclinic mineral, FeSO (sub 4) .5H (sub 2) O ; chalcanthite group; light green.

sides
 * A local New York and Pennsylvania term applied by bluestone quarrymen to open joints that extend east and west.

side shearing
 * In salt mining, a vertical cut at each end of the room that permits the explosive to expand with the least resistance, thus promoting efficiency and power economy.

side shelves
 * The shelves fastened along the sides of the entry throughout the explosion zone on which dust is placed in explosion testing in an experimental mine or gallery.

side shot
 * A reading or measurement from a survey station to locate a point that is off the traverse or that is not intended to be used as a base for the extension of the survey. It is usually made to determine the position of some object that is to be shown on a map.

side slicing
 * See: top slicing combined with ore caving.

side spit
 * The emission of sparks through the sides of a burning fuse.

side stoping
 * See: overhand stoping.

side thrust
 * a. The lateral force against the borehole walls resulting from the buckling or sag in the drill rods at one or more points above the bit.

b. The lateral force developed when the area covered by the bit is not uniformly hard.

sidetracked
 * a. A term applied when tools or downhole drilling equipment is not recovered from a borehole because of the drilling-by or bypassing techniques used.

b. A term applied when a borehole has been deflected, so as to bypass an obstruction.

sidetracked hole
 * Drill purposely directed away from a normal, straight course in order to bypass an obstruction or to straighten the hole; or to redirect the deeper portion by redrilling to an alternate bottom-hole location. See also: directional drilling; deviation.

sidetracking
 * The deliberate act or process of deflecting and redrilling the lower part of a borehole away from a previous course.

side trees
 * a. Posts ranging from 3 to 6 in (7.6 to 15.2 cm) in thickness which support both the head trees and sideboards in a heading.

b. The two posts of a heading set. See also: headtree.

sidewall core
 * A core or rock sample extracted from the wall of a drill hole, either by shooting a retractable hollow projectile, or by mechanically removing a sample.

sidewall coring tool
 * An eccentric sampling device that gouges a small sample, sometimes in the form of a core, from the sidewall of a borehole. Syn: sidewall sampler.

sidewalls
 * a. Walls, usually masonry, at each end of a culvert.

b. See: endwall.

sidewall sampler
 * See: sidewall coring tool.

sidewall sampling
 * The process of securing samples of formations from the sides of the borehole anywhere in the hole that has not been cased.

siding over
 * A short road driven in a pillar in a headwise direction.

Siebe-Gorman self-rescuer
 * A self-rescuer consisting of a hermetically sealed, quick-release canister with inhalation and exhalation valves fitted to the top, a head strap, a rubber mouthpiece, a chin rest, and a nose clip. It is carried on a miner's belt and weighs only 22 oz (0.62 kg). The air enters at the perforated diaphragm in the bottom of the canister, and passes through layers of filters before it reaches the mouthpiece. The complete respirator is held in position by a head strap. See also: self-rescuer.

siegburgite
 * A fossil resin from the brown coal near Bonn, Germany; it ranges in color from golden yellow to brownish red, and is partly soluble in alcohol and ether.

siege
 * The floor of a pot furnace, often called bench.

siegenite
 * An isometric mineral, (Ni,Co) (sub 3) S (sub 4) ; linnaeite group.

Siemens and Halske process
 * A metallurgical process for the recovery of copper. Copper sulfides are dissolved by solutions of ferric sulfate containing free sulfuric acid, and the solution is then electrolyzed in a tank having a diaphragm. Copper is deposited, and ferric sulfate is regenerated.

Siemens direct process
 * A process for making wrought iron directly from iron ore, without the previous production of pig iron.

Siemens furnace
 * A reverberatory furnace, heated by gas, with the aid of regenerators.

siemensite
 * A highly refractory material, produced by the fusion of chromite, bauxite, and magnesite, in an open electric arc furnace.

Siemens-Martin process
 * The production of steel in a reverberatory furnace by oxidation of the impurities by oxides added (either the rust on scrap, mill scale, or pure ores). It may be conducted on either acid or basic lining. See also: open-hearth process.

Siemens producer
 * A furnace used for the manufacture of producer gas.

Siemens-Silesian furnace
 * A Silesian zinc-distillation furnace employing the Siemens system of heat recuperation.

sienna
 * a. A brownish orange-yellow clay colored by iron and manganese oxides; used as a pigment.

b. See: mineral paint. CF: umber.

sierra
 * a. A high range of hills or mountains, esp. one having jagged or irregular peaks that when projected against the sky resemble the teeth of a saw; e.g., the Sierra Nevada in California. The term is often used in the plural, and is common in the Southwestern United States and in Latin America. Syn: serra.

b. A mountainous region in a sierra. Etymol: Spanish, saw, from Latin serra, saw.

Sierra Leone
 * A diamond from the Sierra Leone District in Africa.

sieve
 * a. A laboratory vessel, the bottom of which is a woven-wire screen, used to separate soil or sedimentary material according to the size of its particles; it is usually made of brass, with the wire-mesh cloth having regularly spaced square holes of uniform diameter. CF: screen.

b. The screen or grating fixed in a stamp box. c. Vessel, the bottom of which is porous, with apertures of defined size and shape, allowing contents to be retained as oversize or sieved through as undersize. The chief sieve systems used in laboratory work are rings 8 in (20.3 cm) in diameter with woven wire cloths so specified. d. This term is generally reserved for testing equipment; the corresponding industrial equipment is generally called a screen. There are several standard series of test sieves; those most frequently met with in the ceramic industry are British standard sieves (conforming with B.S. 410), United States standard sieves (conforming with National Institute of Standards and Technology LC-584 or ASTM-E11), French standard sieves (AFNOR NF 11-501), and German standard sieves (DIN 4188). In Tyler sieves, the ratio between the mesh sizes of successive sieves in the series is 2; thus, the areas of the openings of each sieve are double those of the next finer sieve.

sieve analysis
 * Determination of the particle-size distribution in a soil, sediment, or rock by measuring the percentage of the particles that will pass through standard sieves of various sizes. Syn: sieve classification.

sieve bend
 * Stationary screen with close-spaced wedge wire bars across wet pulp feed, set around arc of circle.

sieve classification
 * The separation of powder into particle size ranges by the use of a series of graded sieves. Syn: sieve analysis.

sieve fraction
 * In powder metallurgy, that portion of a powder sample that passes through a standard sieve of specified number and is retained by some finer sieve of specified number.

sieve mesh
 * a. Standard opening in sieve or screen, defined by four boundary wires (warp and woof). The laboratory mesh is square and is defined by the shortest distance between two parallel wires as regards aperture (quoted in micrometers or millimeters), and by the number of parallel wires per linear inch as regards mesh. Sixty mesh equals 60 wires/in (152 wires/cm).

b. The length of the side of a hole in a sieve. See also: mesh.

sieve scale
 * Term applied to the list of screen apertures, taken in order from the coarsest to the finest.

sieve shakers
 * Mechanized devices on which a nest of laboratory sieves can be shaken or electrically vibrated during the size analysis of sands.

sieve sizes
 * Sieves are standardized in British Standard 410 and sieve size diamond powders in British Standard 1987.

sieve texture
 * See: poikiloblastic.

sieving
 * a. Grading in accordance with particle size and shape by means of sieves or screens.

b. The operation of shaking loose materials in a sieve so that the finer particles pass through the mesh bottom. By using a number of sieves with different meshes, the particles can be graded according to size. Syn: sifting.

sifting
 * See: sieving.

sight
 * a. A bob or weighted string hung from an established point in the roof of a room or entry, to give direction to the miners driving the entry or room.

b. A bearing or angle taken with a compass or transit when making a survey. c. Any established point of a survey.

sight distance
 * The distance from which an object at eye level remains visible to an observer.

sighting hub
 * A stake or mark used by a driller as a means of setting and orienting a drill so that the borehole can be drilled to follow a predetermined directional course.

sight line
 * Established compass or transit course for alignment of working places, usually marked on the roof.

sights
 * Bobs or weighted strings hung from two or more established points to give direction to miners driving a chamber or gangway.

sigloite
 * A triclinic mineral, FeAl (sub 2) (PO (sub 4) ) (sub 2) (OH) (sub 3) .7H (sub 2) O ; paravauxite group.

sigma heat
 * See: total heat.

sigma recording methanometer
 * See: butane flame methanometer.

signal code
 * See: hoist signal code.

signaling system
 * The arrangement in use for transmitting signals to stop or start conveyors, rope haulages, locomotives, winders, etc. See also: face signaling; loudspeaker face telephone.

signal system
 * See: mine fan signal system; hoist signal system.

significant anomaly
 * An anomaly that is related to ore and that can be used as a guide in exploration. See also: geochemical anomaly.

silcrete
 * a. A term suggested by Lamplugh (1902) for a conglomerate consisting of surficial sand and gravel cemented into a hard mass by silica. Examples occur in post-Cretaceous strata of the United States.

b. A siliceous duricrust. Etymol: "sil"iceous + con"crete." CF: calcrete; ferricrete.

silent chain
 * A roller-type chain in which the sprockets are engaged by projections on the link side bars.

silex
 * a. The French term for flint.

b. Silica; esp. quartz, such as a pure or finely ground form for use as a filler. c. An old term formerly applied to a hard, dense rock, such as basalt or compact limestone. Etymol: Latin, hard stone, flint, quartz. The term was used by Pliny for quartz.

silexite
 * a. An igneous rock composed essentially of primary quartz (60% to 100%), e.g., a quartz dike, segregation mass, or inclusion inside or outside its parent rock.

b. The French term for chert; specif. chert occurring in calcareous beds. See also: chert.

silica
 * The chemically resistant dioxide of silicon, SiO (sub 2) ; occurs naturally as five crystalline polymorphs: trigonal and hexagonal quartz, orthorhombic and hexagonal tridymite, tetragonal and isometric cristobalite, monoclinic coesite, and tetragonal stishovite. Also occurs as cryptocrystalline chalcedony, hydrated opal, the glass lechatelierite, skeletal material in diatoms and other living organisms, and fossil skeletal material in diatomite and other siliceous accumulations. Also occurs with other chemical elements in silicate minerals.

silica brick
 * a. Refractory bricks used to line roofs of furnaces, where there is no contact with basic molten material.

b. Silica cemented with a binding agent, for example, slurried lime.

silica-firebrick molder
 * One who forms silica brick for use in lining furnaces and ovens of various kinds.

silica refractories
 * Refractories made from quartzite, bonded by lime, and consisting essentially of silica, usually with about 2% of lime, and small quantities of iron oxide, alumina, and alkalies.

silica rock
 * An industrial term for certain sandstones and quartzites that contain at least 95% silica (quartz). It is used as a raw material of glass and other products. CF: silica sand.

silica sand
 * An industrial term for a sand or an easily disaggregated sandstone that has a very high percentage of silica (quartz). It is a source of silicon and a raw material of glass and other industrial products. CF: silica rock.

silicate
 * a. A compound whose crystal structure contains SiO (sub 4) tetrahedra, either isolaed or joined through one or more of the oxygen atoms to form groups, chains, sheets, or three-dimensional structures with metallic elements. Silicates were once classified according to hypothetical oxyacids of silicon (see metasilicate and orthosilicate) but are now calssified according to crystal structure (see nesosilicate, sorosilicate, cyclosilicate, inosilicate, phyllosilicate, tectosilicate).

b. A term used in the Joplin district, Missouri, for zinc carbonate.

silicate brick
 * Usually refers to Forsterite brick. Strictly, most bricks are silicate bricks of one kind or other.

silicate degree
 * In the metallurgical nomenclature of slags, the ratio of the weight of oxygen in the acid to the weight of oxygen in the base.

silicate minerals
 * Minerals with crystal structure containing SiO (sub 4) tetrahedron arranged as (1) isolated units, (2) single or double chains, (3) sheets, or (4) three-dimensional networks.

silication
 * The process of converting into or replacing by silicates, esp. in the formation of skarn minerals in carbonate rocks. CF: silicification. Adj: silicated.

silicatization process
 * A special method of sealing off water, for example, reducing its inflow into shafts, by the injection of calcium silicate under pressure. It is sometimes used to reduce the leakage of water through defective lengths of tubbing in a shaft. The calcium silicate is highly impervious on solidification, behind the leaking tubbing.

silicatosis
 * A disease of the lungs thought to be caused by silicates.

siliceous
 * a. Of, relating to, or derived from silica; containing or resembling silica or a silicate; silicic. Also spelled silicious.

b. Said of a rock containing free silica or, in the case of volcanic glass, silica in the norm.

siliceous dust
 * Dust arising from the crushing or other dry working of sand, sandstone, trap, granite, and other igneous rocks is included in this class. Siliceous dusts are not soluble in body fluids, and when introduced into the respiratory tract in the form of particles of certain sizes and in sufficiently high concentration, they produce nodular growths that often result in a form of pneumonoconiosis that has been known as silicosis or "stone cutters" consumption.

siliceous earth
 * A general term including both diatomaceous earth (diatomite) and radiolarian earth (radiolarite).

siliceous fire clay
 * A fire clay composed mainly of fine white clay mixed with clean, sharp sand, found in pockets.

siliceous materials
 * Materials that consist mainly of SiO (sub 2) and must be low in metallic oxides and alkalies.

siliceous oozes
 * These are pelagic deposits that contain a large percentage of siliceous skeletal materials produced by planktonic plants and animals. The siliceous oozes are subdivided into two types on the basis of the predominance of the forms represented, namely (1) diatom ooze, containing large amounts of diatom frustules, therefore, produced by plankton plants, and (2) radiolarian ooze, containing large porportions of radiolarian skeletons formed by these plankton animals.

siliceous ore
 * Another name for gold-quartz ores.

siliceous rocks
 * Generally, rocks high in silica.

siliceous shale
 * A hard, fine-grained rock of shaly structure generally believed to be shale altered by silicification. Syn: phthanite. See also: porcellanite.

siliceous sinter
 * The lightweight porous opaline variety of silica, white or nearly white, deposited as an incrustation by precipitation from the waters of geysers and hot springs. The term has been applied loosely to any deposit made by a geyser or hot spring. Syn: sinter; pearl sinter; geyserite; fiorite.

silicic
 * a. In petrology, containing silica in dominant amount.

b. In chemistry, containing silicon as the acid-forming element. c. Said of a silica-rich igneous rock or magma. Although there is no firm agreement among petrologists, the amount of silica is usually said to constitute at least 65% or two-thirds of the rock. In addition to the combined silica in feldspars, silicic rocks generally contain free silica in the form of quartz. Granite and rhyolite are typical silicic rocks. The synonymous terms "acid" and "acidic" are used almost as frequently as silicic. Syn: acidic; intermediate; persilicic. CF: basic; ultrabasic.

silicification
 * a. The introduction of, or replacement by, silica, generally resulting in the formation of fine-grained quartz, chalcedony, or opal, which may fill pores and replace existing minerals. CF: silication. Adj: silicified. Syn: silification.

b. A process of fossilization whereby the original organic components of an organism are replaced by silica, as quartz, chalcedony, or opal.

silicified
 * Adj. of silicification.

silicified wood
 * A material formed by replacement of wood by silica in such manner that the original form and structure of the wood is preserved. The silica is generally in the form of opal or chalcedony. Syn: petrified wood; woodstone; agatized wood; fossilized wood; opalized wood; shinarump.

silicinate
 * Said of the silica cement of a sedimentary rock.

silicious ore
 * See: natural ore.

silicon
 * A nonmetallic element that is the second most abundant on Earth, being exceeded only by oxygen. Symbol, Si. Silicon is not found free in nature, but occurs as the oxide and silicate. Sand, quartz, rock crystal, amethyst, agate, flint, jasper, and opal are some of the forms in which the oxide appears. Hornblende, orthoclase, kaolin, and biotite are a few of the numerous silicate minerals. Used in the electronics and space-age industries; used to make concrete, brick, and glass. Miners often develop a serious lung disease, silicosis, from breathing large quantities of the dust.

silicon alloys
 * Silicon bronze is a noncorroding alloy with copper and tin. Silicon copper (70% to 80% copper and 20% to 30% silicon) is an alloy added to molten copper or brass to remove oxygen. Silicon iron is a grain-improved iron, corrosion resistant. See also: ferrosilicon.

silicon borides
 * Two compounds have been reported: SiB (sub 4), oxidation resistant to 1,370 degrees C; SiB (sub 6) , melting point 1,950 degrees C. A special refractory has been made by reacting silicon and boron in air, the product containing SiB (sub 4) and Si in a borosilicate matrix; it is stable in air to at least 1,550 degrees C and has good thermal shock resistance. Syn: boron silicides.

silicon copper
 * A rich copper alloy added to molten copper in order to secure clean, solid castings free from blowholes, swellings, etc.

silicon dioxide
 * See: silica.

siliconize
 * To unite or cause to unite with silicon, as in the combination of iron with silicon in certain metallurgical processes.

silicon-oxygen tetrahedron
 * A fundamental structural unit of silicate minerals formed by four oxygen ions surrounding one silicon ion such that lines connecting the four oxygen nuclei show the outline of a geometric tetrahedron. It is commonly written SiO (sub 4) with the electronic charge of minus 4 for the unit assumed. See also: silicate.

silicon spiegel
 * a. A spiegeleisen containing 15% to 20% manganese and 8% to 15% silicon used in making certain special steels.

b. A form of pig iron.

silicon steel
 * A variety of steel containing up to 5% silicon. It is very hard, but is brittle and difficult to work.

silicosis
 * a. Lung disease caused chiefly by inhaling rock dust from air drills.

b. A condition of massive fibrosis of the lungs marked by shortness of breath and resulting from prolonged inhalation of silica dusts by those--such as stonecutters, asbestos workers, miners--regularly exposed to such dusts. See also: pneumoconiosis; simple silicosis; mining disease.

silicotuberculosis
 * Complication of tuberculosis by silica.

silification
 * See: silicification.

silk
 * Microscopically small, needlelike inclusions of rutile crystals in a natural gem, such as ruby, sapphire, or garnet, from which subsurface reflections produce a whitish sheen resembling that of silk fabric.

silklay
 * A finely ground-plastic clay of high refractoriness used as a bond for molding sands.

silky luster
 * a. The luster of silk, peculiar to minerals having a fibrous structure. The fibrous form of gypsum and satin spar are good examples of silky luster.

b. A type of mineral luster characteristic of some fibrous minerals, such as chrysotile and gypsum.

sill
 * a. Applied in mining to flat-bedded strata of sandstone or similar hard rocks.

b. A concordant sheet of igneous rock lying nearly horizontal. A sill may become a dike or vice versa. c. The floor of a gallery or passage in a mine. d. Fireclay, used for making slate or sill pencils, Coal Measures. CF: stone sill. e. See also: floor sill. f. A submarine ridge or rise at a relatively shallow depth, separating a basin from another basin or from an adjacent sea and causing the basin to be partly closed, e.g., in the Straits of Gibraltar. g. A ridge of bedrock or earth material at a shallow depth near the mouth of a fjord, separating the deep water of the fjord from the deep ocean water outside. Syn: threshold. h. The upper limit of any variogram model that has such a limit, i.e., that tends to "level off" at large distances. The spherical, gaussian, exponential, and nugget models have sills. For the linear model, "sill/range" is used merely to define the slope.

sill depth
 * Greatest depth at which there is free, horizontal communication between two ocean basins.

sillenite
 * An isometric mineral, Bi (sub 12) SiO (sub 20) ; forms greenish, earthy or waxy masses; at Durango, Mexico.

sillimanite
 * a. An orthorhombic mineral, Al (sub 2) SiO (sub 5) ; trimorphous with kyanite and andalusite; forms long, slender, needlelike crystals commonly in wisplike or fibrous aggregates (fibrolite) in gneisses and schists at granulite grade; also occurs in alluvial deposits. It forms at the highest temperatures and pressures of a regionally metamorphosed sequence and is characteristic of the innermost zone of contact-metamorphosed sediments. CF: mullite; fibrolite.

b. Loosely used for the aluminum silicate minerals sillimanite, kyanite, andalusite, dumortierite, topaz, and mullite. c. A high heat-resisting ceramic material containing a maximum amount of mullite, developed from the alteration of andalusite during firing to 1,550 degrees C and used for special porcelain shapes, furnace patches, and refractories.

sillimanite schist
 * A schist containing an appreciable amount of sillimanite (fibrolite).

sillite
 * Gumbel's name for a rock from the Bavarian Alps, variously referred to by others as gabbro, diabase, mica syenite, and mica diorite.

sills
 * Strong timbers laid horizontally to support posts or other tunnel timbers.

silo
 * A tall tower, usually cylindrical and of reinforced concrete construction, in which grain, cement, coal, or similar bulk material is stored.

silt
 * a. In anthracite terminology, the accumulation of waste fine coal, bone, and slate settled out of breaker water. It is made up of particles ranging in size from 3/32-in (2.4-mm) round-opening to the finest slime. The material is also called sludge, culm, fines, slush, and mud. It is the partly dewatered solids content of what has been defined as slurry. See also: rock flour.

b. In bituminous coal terminology: Syn: coal sludge. c. Material passing the No. 200 U.S. standard sieve that is nonplastic or very slightly plastic and that exhibits little or no strength when air-dried. d. Breaker waste composed of water, coal, slate, pyrite, and clay.

siltation
 * See: silting.

silt box
 * A loose iron box fitted in the bottom of a gulley for collecting deposited silt. It can be removed periodically for emptying and flushing.

silt displacement
 * A system of using a shield for driving a tunnel in silts that are nearly fluid.

silting
 * a. The deposition or accumulation of silt that is suspended throughout a body of standing water or in some considerable portion of it; esp. the choking, filling, or covering with stream-deposited silt behind a dam or other place of retarded flow, or in a reservoir. The term often includes sedimentary particles ranging in size from colloidal clay to sand. Syn: siltation.

b. Sedimentation in water that results in the deposition of somewhat fine material, which is suspended in the entire body of water or in some considerable portion of it. c. Filling with soil or mud deposited by water. See also: hydraulic mine filling.

silting up
 * The filling, or partial filling, with silt, as of a reservoir that receives fine-grained sediment brought in by streams and surface runoff. The term has been used synonymously with sedimentation without regard to any specific grain size.

siltite
 * See: siltstone.

siltstone
 * An indurated silt having the texture and composition of shale but lacking its fine lamination or fissility; a massive mudstone in which the silt predominates over clay; a nonfissile silt shale. It tends to be flaggy, containing hard, durable, generally thin layers, and often showing various primary current structures. Syn: siltite. See also: mudstone; claystone.

silt trap
 * A settling hole or basin that prevents water-borne soil from entering a pond or drainage system.

Silurian
 * A period of the Paleozoic, thought to have covered the span of time between 440 and 400 million years ago; also, the corresponding system of rocks. The Silurian follows the Ordovician and precedes the Devonian; in the older literature, it was sometimes considered to include the Ordovician. It is named after the Silures, a Celtic tribe.

silver
 * a. A white metallic element that is very ductile and malleable. Symbol, Ag. Occurs native and in ores such as argentite and horn silver; lead, lead-zinc, copper, gold, and copper-nickel ores are its principal sources. Used for jewelry, photography, dental alloys, and coinage.

b. An isometric or hexagonal mineral, Ag, native silver; commonly alloyed with Hg or Au; soft; metallic; sp gr, 10.5; in oxidized zones of hydrothermal deposits.

silver amalgam
 * a. A solid solution of mercury and silver crystallizing in the cubic system. The percentage of silver is usually about 26%, but in the variety arquerite it reaches 86%. It is of rare occurrence, and is found scattered either in mercury or silver deposits.

b. A naturally occurring "amalgam," an isometric mineral, (Ag,Hg); rarely found scattered either in mercury or silver deposits. See also: amalgam.

silver bonanza
 * A rich silver mine.

silver-copper glance
 * See: stromeyerite.

silver freighter
 * A wagoner who hauls silver ore.

silver glance
 * The native silver sulfide, argentite.

silver halides
 * Silver bromide, AgBr; silver iodide, AgI; silver chloride, AgCl; and silver fluoride, AgF. The bromide and chloride are sensitive to light and are of basic importance in photography.

silvering
 * a. A plating or covering of silver or an imitation of it, as applied to any surface; as, the silvering on the back of a mirror.

b. The art or process of coating surfaces with silver.

silver lead
 * Lead containing silver.

silver lead ore
 * The name given to galena containing silver. When 1% or more of silver is present, it becomes a valuable ore of silver. Syn: argentiferous galena.

silver minerals
 * Occurs native, alloyed with gold as electrum, as sulfide argentite, Ag (sub 2) S, proustite, pyrargyrite, and horn silver, AgCl, or cerargyrite. Main source is argentiferous ores of lead, zinc, and copper where it is extracted as a byproduct. Bulk of production is used for coinage, electrical alloys, photographic chemicals, and the arts.

silver sand
 * a. A sharp, fine sand of a silvery appearance used for grinding lithographic stones, etc.

b. Specially pure silica.

sima
 * a. The basic outer shell of the Earth; under the continents it underlies the sial, but under the oceans it directly underlies the water. Originally, the sima was considered basaltic in composition with a specific gravity of about 3.0. In recent years, it has been suggested that the sima is peridotitic in composition with a specific gravity of about 3.3. First used in its present form and spelling by Suess.

b. A petrologic name for the lower layer of the Earth's crust, composed of rocks that are rich in silica and magnesia. It is equivalent to the oceanic crust and to the lower portion of the continental crust, underlying the sial. Etymol: an acronym for silica + magnesia. Adj: simatic. CF: sial; sialma. Syn: intermediate layer; basaltic layer.

Simbal breathing apparatus
 * An improved liquid oxygen breathing apparatus, weighing 33 lb (15 kg) and approved for use in British mines. Air is fed to the wearer at a temperature of 50 degrees F (10 degrees C) rising to 70 degrees F (21.1 degrees C) in just over 1/2 h and is still only 80 degrees F (26.7 degrees C) after 2-1/2 h.

simetite
 * A deep-red to light orange-yellow variety of amber having a high content of sulfur and oxygen and a low content of succinic acid; occurs in the waters off Sicily.

similar fold
 * A fold in which the orthogonal thickness of the folded strata is greater in the hinge than in the limbs, but the distance between any two folded surfaces is constant when measured parallel to the axial surface. Thus, if the shape of one bed is that of a sine curve, all the beds show the same shape. Similar folds show thinning on the limbs and thickening at the axes. CF: parallel fold; supratenuous fold. Syn: concentric fold.

similor
 * A golden-colored variety of brass. Also called Mannheim gold; Prince Rupert's metal.

simonyite
 * See: bloedite.

simple beam
 * A simply supported beam.

simple bending
 * The bending of a beam that is freely supported, having no fixed end.

simple explosives
 * These explosives consist of one simple chemical compound. The explosive heat is liberated with the breaking down of the molecules and the atoms recombining to form water, carbon dioxide, nitrogen and other gases, and possibly solid substances such as carbon. To this group belong explosives in the proper sense of the word, such as nitroglycerin, nitroglycol, nitrocellulose, trotyl, and cyclonite (RDX). Also includes "molecular explosives."

simple kriging
 * A variety of kriging that assumes that local means are relatively constant and equal to the population mean, which is well known. The population mean is used as a factor in each local estimate along with the samples in the local neighborhood. This is not usually the most appropriate method for environmental situations.

simple mineral
 * A mineral found in nature, as distinguished from rocks, which, in the scientific sense, are mixtures of minerals. Calcite and hematite are simple minerals, while granite is a mixture of three simple minerals--quartz, feldspar, and mica.

simple ore
 * Ore that yields a single metal. CF: complex ore.

simple pneumoconiosis
 * Pneumoconiosis of the lungs that can be related to the amount (and possibly the nature) of the dust breathed by miners over the years. See also: complicated pneumoconiosis.

simple silicosis
 * Silicosis that is not complicated by tuberculosis; a condition that may remain almost stationary for many years. See also: mining disease.

simple split seam
 * A coal seam that has separated into two layers of coal some distance apart vertically. See also: multiple splitting.

Simplex pump
 * A reciprocating single- or double-action piston pump having one water cylinder.

simplotite
 * A monoclinic mineral, CaV (sub 4) O (sub 9) .5H (sub 2) O ; dark green.

simpsonite
 * A trigonal mineral, Al (sub 4) (Ta,Nb) (sub 3) (O,OH,F) (sub 14) ; yellow-brown.

Simpson's rule
 * A rule for estimating the area of an irregular figure after dividing it into an even number of parallel strips of equal width. See also: trapezoidal rule.

simulated insert bit
 * A core bit in the face of which are deeply cut, closely spaced waterways to produce the superficial appearance of an insert-type bit. Also called Thedford crown bit.

simulated workplace protection factor
 * A surrogate measure of the workplace protection provided by a respirator.

simultaneous filling
 * Filling in which the mined-out area or room is filled immediately after mining out only a small part of the deposit.

simultaneous shot firing
 * The concurrent firing of a round of shots using instantaneous detonators.

sincosite
 * A tetragonal mineral, Ca(VO) (sub 2) (PO (sub 4) ) (sub 2) .5H (sub 2) O ; a vanadium analog of the meta-autunite group; green; a source of vanadium.

sing
 * A hissing noise often made by gas and water when a seam of coal is cut into.

singing
 * a. Resonance phenomenon that is frequently observed on marine seismograms.

b. A seismic resonance phenomenon that is produced by short-path multiples in a water layer. Syn: reverberation; ringing.

single-acting ram
 * See: one-way ram.

single-action pump
 * A pump valved so as to discharge liquid at only one end of the water cylinder. CF: double-action pump.

single-approach pit bottom
 * A pit-bottom layout at a mine where development branches off on one side only. The empty cars are returned from the opposite side by a loop, shunt back, turntable, or traverse. See also: loop-type pit bottom.

single-bench quarrying
 * Quarrying a rock ledge as a single bench the full height of the quarry face.

single block
 * A block with one pulley or sheave.

single consignment
 * A quantity of coal that is to be sampled to a specified accuracy. It is used in contradistinction to the sampling of a coal received regularly at a given point. See also: isolated consignment.

single-core shot-firing cable
 * See: shot-firing cable.

single crystal
 * A crystal, usually grown artificially, in which all parts have the same crystallographic orientation.

single-cut sprocket
 * For double-pitch roller chains, a sprocket having one set of effective teeth.

single-deck screen
 * A screen having one screening surface, not necessarily limited to one size or shape of aperture.

single entry
 * A system of opening a mine by driving a single entry only, in place of a pair of entries. The air current returns along the face of the rooms, which must be kept open.

single-entry room-and-pillar mining
 * See: room-and-pillar.

single-entry zone test
 * A test in which coal dust is placed only in a single entry.

single-grained structure
 * An arrangement composed of individual soil particles; characteristic structure of coarse-grained soils. See also: soil structure; flocculent structure; honeycomb structure.

single-hand drilling
 * Rock drilling by hand; e.g., in narrow reefs. A drill steel held in the left hand is struck blows with a 4-lb (1.8-kg) hammer, the drill being turned between the blows. The drilling is very slow and laborious.

single-inlet fan
 * A centrifugal fan in which air enters the impeller at one side only.

single-intake fan
 * A ventilating fan that takes or receives its air from one side only.

single jack
 * a. A lightweight hammer, usually 4 lb (1.8 kg) or less. When used in hand drilling holes in rock, the hammer is held in one hand and the drill is held in the other.

b. Sometimes incorrectly used to designate a sinker drill. c. A drill column having a single jackscrew in the bottom end. See also: drill column.

single-layer bit
 * See: surface-set bit.

single opening
 * Any underground opening separated from a free surface by a distance greater than three times the size of the opening in the direction of the free face.

single outlet
 * For safety reasons, mines with only a single outlet (shaft) are subjected to restrictions in the numbers of mine workers employed at a time.

single packing
 * The conventional method of strip packing on a longwall face, in which the widest pack is along the roadside. A single packing system varies but may have a 10-yd (9.1-m) roadside pack, then 7 yd (6.4 m) of waste, followed by 4-yd (3.7-m) packs and 5 yd (4.6 m) of waste repeated across the entire face. See also: double packing; strip packing.

single-phase circuit
 * A two-wire circuit using alternating current.

single-pulley-drive conveyor
 * A conveyor in which power is transmitted to the belt by one pulley only.

single refraction
 * Light refraction in an isotropic crystal or amorphous substance according to Snell's law, as opposed to the birefringence of an anisotropic crystal.

single-road stall
 * S. Wales. A system of working coal by narrow stalls.

single-roll breaker
 * A coal-crushing machine in which the roll teeth crack downward on the lump and the roll itself compresses the coal against the breaker plates. Teeth of two or more designs are used generally on the same roll, some for the slugging, cracking, or blow action and others for a pulling and splitting force. The breakers are not easy to stall by choking, since they will pass a heavy overload, partly because of the action of a relief mechanism, with which they are all equipped.

single-roll crusher
 * A crushing machine consisting of a rotating cylinder with a corrugated or toothed outer surface that crushes material by pinching it between the teeth and stationary breaking bars. CF: double-roll crusher.

single-rope friction pulley
 * See: Koepe sheave.

single-rope haulage
 * A system of underground haulage in which a single rope is used, the empty trip running in by gravity. Engine-plane haulage.

single-round nose
 * The cross-sectional view of the cutting-face portion of a core bit when the profile is an arc having a radius equal to or greater than the wall thickness. See also: profile. CF: double-round nose.

single-round-nose bit
 * See: single-round nose.

single-row blasting
 * The drilling, charging, and firing of a single row of vertical holes along a quarry or opencast face. The holes may be fired simultaneously or by delay detonators to give a peeling action starting at one end of the face. See also: multiple-row blasting.

single shot
 * A charge in one drill hole only fired at one time, as contrasted with a multiple shot where charges in a number of holes are fired at one time.

single-shot blasting unit
 * A single-shot blasting unit is a unit designed for firing only one explosive charge at a time. Syn: blasting unit.

single-shot exploders
 * Exploders of the magneto type that are operated by the twist action given by a half-turn of the firing key. A magneto exploder consists essentially of a small armature that can be rotated between the poles of a set of permanent magnets. The armature is rotated by means of toothed gear wheels actuated by the movement of the firing key. The electric circuit between the exploder and the detonator is completed by means of an automatic internal switch operating at the end of the stroke, or contact may be made by means of a pushbutton.

single-shot instrument
 * A borehole surveying instrument that records only one measurement of the bearing and of the inclination of a hole on a single trip into the borehole.

single-shot survey
 * A borehole survey made with a single-shot instrument.

single sling
 * A sling that has a single hook at one end and an iron or steel ring at the other. See also: two-leg sling.

single-speed floating control system
 * In flotation, floating control in which the manipulated variable changes at a fixed rate, increasing or decreasing depending on the sign of the actuating signal.

single-spot method
 * One of three recognized methods of determining the average velocity of airflow along a mine roadway by anemometer. A velocity reading is taken at the center of the airway and the result is multiplied by the center constant, whose value ranges between 0.8 and 0.9, to give the average velocity of flow. Alternatively, the reading is taken along a midway line at a position some one-seventh to one-third of the width of the airway, measured from the side. At this position, the mean velocity is obtained, so that no adjustment is required. CF: division method; traversing method.

single-stage pump
 * A centrifugal pump with a lift of 100 ft (30.5 m) per stage.

single-stall working
 * See: room-and-pillar.

single stamp mill
 * a. A mill possessing batteries of one stamp each, like the Nissen, instead of the usual five.

b. A mill possessing only one stamp, after the Lake Superior fashion, where one big stamp does the work of 150 ordinary gravity stamps.

single-toggle jaw crusher
 * A jaw crusher with one jaw fixed, the other jaw oscillating through an eccentric mounted near its top. This type of jaw crusher has a relatively high output, and the product is of fairly uniform size.

single-unit panel
 * A longwall conveyor face from about 80 to 200 yd (73 to 183 m) long developed between two gate roads, one serving as an intake airway and usually for coal haulage, while the other acts as a return airway and for bringing in supplies to the face. See also: double-unit conveyor.

single vein
 * A single ore deposit of identical origin, age and character throughout. A single small vein is weighed and measured by the same law and entitled to the same consideration as the mother lode, and very often is far more valuable in the eyes of the miner.

singulosilicate
 * A slag with a silicate degree of 1.

sinhalite
 * An orthorhombic mineral, MgAlBO (sub 4) ; structurally analogous to olivines; yellow.

sinistral fault
 * See: left-lateral fault.

sink
 * a. To excavate or drive a shaft or slope.

b. The depression in a shaft made by a center blast. c. A water lodgment. See also: sump. d. To put standpipe or casing down through overburden by rotation or by driving, chopping, or washing-- these methods being employed singly or in combination. e. To drill or put down a borehole. f. A depression in the land surface, esp. one having a central playa or saline lake with no outlet; a hollow in a limestone region communicating with a cavern or subterranean passage so that waters running into it disappear. Also called sinkhole; swallow hole. g. Lanc. Natural cavity found in iron mines.

sinker
 * a. A rock drill for drilling blasting holes in a sinking shaft.

b. A special movable pump used in shaft sinking. c. See: sinker bar. d. A person who sinks mine shafts and puts in supporting timber or concrete.

sinker bar
 * a. A heavy rod used to increase the snatching effect of the sliding jars in rope drilling.

b. A short bar or stem placed above the drill jars to give force to the upward jar in well drilling with cable tools.

sinker drill
 * a. A one-person drill that can be held in the hand but is frequently mounted. This drill has found wide application in sinking shafts and is made in several sizes, each suited for a particular kind of work. Also called plugger drill.

b. A rock drill of the jackhammer type commonly used in shaft sinkings. Also called sinker. c. A hand-held compressed-air rock drill used in boring down holes such as in shaft sinking.

sink-float processes
 * Processes that separate particles of different sizes or composition on the basis of specific gravity. When ore or coal particles are introduced into a liquid (or into a medium: a solid suspension), those having a specific gravity higher than that of the liquid will sink, while those that are lighter than the liquid will float.

sink-float separation
 * See: dense-media separation.

sinkhole
 * A circular depression in a karst area. Its drainage is subterranean, its size is measured in meters or tens of meters, and it is commonly funnel shaped. Syn: doline; sink; leach hole. Partial syn: collapse sink.

sinking
 * a. The process by which a shaft is driven.

b. Extending excavations downward at or near the vertical plane. See also: raising; shaft sinking.

sinking fire
 * A forge in which wrought-iron scrap or refined pig iron is partly melted or welded together by means of a charcoal fire and a blast.

sinking head
 * See: deadhead.

sinking in rock
 * Shaft sinking in rock usually comprises the following cycle: drilling a round of holes, blasting, removing the broken rock, trimming the shaft to form, placing the sets or concrete in position, and then preparing to drill the next round.

sinking kibble
 * A large bucket for raising the stones, etc., from a shaft being sunk. Sometimes called bowk; hoppett.

sinking lift
 * A lift (pump) of small size with esp. heavy castings to resist the force of blasting; used in shaft sinking. A sinking pump, which is also sometimes called a sinker.

sinking plant
 * In a shaft, a sinking plant consists of the headframe, hoisting equipment, air-compressor for drills, concrete-mixing equipment, and suitable pumps. It may be temporary or permanent.

sinking platform
 * A scaffold or staging designed for use during shaft sinking, particularly during lining operations.

sinking pump
 * A long, narrow pump designed for keeping a shaft dry during sinking operations. It is usually large enough to deal with 1,000 gal/min (3,780 L/min) from the greatest depth at which water will be encountered. A sinking pump must be slung from the surface and be fairly easy to raise and lower when shot firing takes place at the shaft bottom. Most are of the electrically driven centrifugal type and allow for additional stages to be fitted as the shaft depth increases. It may be suspended by a single-drum, worm-driven, capstan engine with a very slow speed. See also: borehole pump; water barrel.

sinks
 * Fractions with a defined upper limit of specific gravity and so described, e.g., sinks 1.60 specific gravity.

sinople
 * A red or brownish-red variety of quartz containing inclusions of hematite. Also spelled sinopal; sinopel.

sinter
 * a. A chemical sedimentary rock deposited as a hard incrustation on rocks or on the ground by precipitation from hot or cold mineral waters of springs, lakes, or streams; specif. siliceous sinter and calcareous sinter (travertine). The term is indefinite and should be modified by the proper compositional adj., although when used alone it usually signifies siliceous sinter. Etymol: German sinter, cinder. CF: tufa.

b. A ceramic material or mixture fired to less than complete fusion, resulting in a coherent mass when cooled. c. A process for agglomerating ore concentrate in which partial reduction of minerals may take place and some impurities be expelled prior to subsequent smelting and refining. d. To heat a mass of fine particles for a prolonged time below the melting point, usually to cause agglomeration. e. A process commonly used in making diamond bits, whereby powdered metal is compacted in a diamond-set mold or die, and the temperature is raised to a point just below melting, thus fusing the entire mass together. Also called sintered.

sinter bit
 * A bit, the crown of which is formed by applying heat and pressure to a mixture of powdered metals covering diamonds set inside a mold or die-shaped to the form of a bit crown. The bit crown thus formed may be a surface-set, multilayer, or impregnated type.

sinter cap
 * A zone of sinter typically positioned at the top of epithermal systems.

sintered carbide
 * Sintering as used in powder metallurgy consists of mixing metal carbide powders having different melting points, and then heating the mixture to a temperature approximating the lowest melting point of any metal included. In sintered carbides, powdered cobalt, having the lowest melting point, acts as the binder, holding together the unmelted particles of the hard carbides. See also: cemented carbide.

sintered carbide-tipped pick
 * The pick generally used in coal cutters and cutter loaders, in which the sintered tip is brazed in various ways to the shank of the pick. In the external-tip type, which is widely used, the sintered tip is brazed externally to the shank, which is usually a forging. It is self-gaging and as the tip wears down, the cutting edge maintains its shape and clearance. In the slotted type, the tip is brazed into a slot cut in the shank of the pick. In the inserted-rod type, the sintered carbide takes the form of a rod inserted into a hollow in the shank of the pick, which is a forging. These picks are widely used in the soft coal mines in Germany. See also: tungsten carbide bit; coal-cutter pick. Syn: inserted rod-type pick.

sintered matrix
 * A bit-crown diamond-embedment metal or alloy produced by a sinter powder-metal process. See also: sinter; sinter bit.

sintered-metal bit
 * See: sinter bit.

sintering
 * A heat treatment for agglomerating small particles to form larger particles, cakes, or masses; in case of ores and concentrates, it is accomplished by fusion of certain constituents.

sinter plant
 * A plant in which sintering is carried out.

sinter set
 * See: sinter bit.

sinter-set bit
 * See: sinter bit.

sinuous flow
 * See: turbulent flow.

Sioux Falls jasper
 * A decorative brown jasperlike, fine-grained quartz, from Sioux Falls, SD. Used for tables and interior architectural trim.

siphon
 * An arrangement of closed pipes and valves to conduct water from one level to a lower level over an intervening ridge. The difference of level between the inlet and outlet ends of the pipe column must be sufficient to provide a head great enough to overcome the frictional resistance of the pipe column. The siphon was often used in the earlier days of mining when pumps were too costly or power was not available. See also: suction head; inverted siphon.

siphonage
 * The action or operation of a siphon.

siphon separator
 * An apparatus for the sizing of pulverized ores in an upward current of water.

siphon tap
 * See: Arents tap.

sipylite
 * See: typrite.

Sirocco fan
 * A centrifugal fan, invented by Samuel Davidson in 1898, with 64 narrow blades curved forward, mounted at the periphery of a braced, open drum. It is a high-speed, small-diameter fan, usually direct driven. It was a popular fan in Great Britain for many years. See also: Waddle fan.

siserskite
 * Former name for iridosmine.

sismondine
 * Former name for Mg-rich chloritoid.

site exploration
 * a. The investigation and testing of the surface, subsoil, and any obstruction at a site to obtain the full information necessary for designing a complete structure with its foundations.

b. See: site investigation.

site investigation
 * The collection of basic facts about, and the testing of, surface and subsurface materials (physical properties, distribution, and geologic structure) at a site, for the purpose of preparing suitable designs for a mine, an engineering structure, or other use.

site rivet
 * A rivet driven on a construction site. See also: shop rivet.

size
 * To separate minerals according to various screen meshes.

size analysis
 * See: particle-size analysis.

size consist
 * Screen analysis of particle size (coal).

size distribution
 * a. See: particle-size distribution.

b. Analysis of crushed or ground materials on the basis of particle size. c. In sizing analysis of sands, the percentage of the sample retained on each laboratory sieve in the range examined.

size-distribution curve
 * A graphical representation of the size analysis of a mixture of particles of various sizes, using an ordinary, logarithmic, or other scale.

sized variation
 * The variation in dimensions of any ceramic product from the intended dimensions.

size fraction
 * Portion of a sample of sand lying between two size limits, the upper being the limiting and the lower the retaining mesh.

size-frequency distribution
 * See: particle-size distribution.

size range
 * That between upper (limiting) and lower (retaining) mesh sizes with reference to screened or classified material.

size reduction
 * The breaking of large coal, ore, or stone by primary breaker, or the breaking of smaller sizes by grinding. See also: reduction ratio; primary breaker.

size selector
 * A device attached to the intake of a dust-sampling instrument to remove the bulk of the particles above 5 to 10 mu m in size; thus the resulting sample is more representative of the health-hazard size range of dust-- mainly 5 mu m and smaller. See also: dust sampling.

sizing
 * a. The arrangement, grading, or classification of particles according to size; e.g., the separation of mineral grains of a sediment into groups each of which has a certain range of size or maximum diameter, such as by sieving or screening.

b. See: screening.

sizing punch
 * A punch used for pressing of the sintered compact during the sizing operation.

sizing screen
 * A screen or set of screens normally used for dividing a product (for example, washed coal) into a range of sizes. Also called grading screen and classifying screen (undesirable usage).

sjoegrenite
 * a. A hexagonal mineral, Mg (sub 6) Fe (sub 2) (CO (sub 3) )(OH) (sub 16) .4H (sub 2) O ; manasseite group; dimorphous with pyroaurite of the hydrotalcite group.

b. The name was formerly used for the phosphates dufrenite and chalcosiderite.

S-joint
 * See: longitudinal joint.

S.J. table
 * A pneumatic table of American design, for the drycleaning of coal. A sizing ratio of 2:1 is desirably the maximum range of sizes that the table can separate in one operation. See also: Kirkup table.