OLD AGE See - Erosion cycles.
OUTCROP The exposure of bedrock or strata projecting through the overlying cover of detritus and soil. (AGI)
OUTLET The point where a channel is cut off by a ravine or canyon on the downstream end. (Dunn, R.L.) Usually applied to buried Tertiary channels. Compare with Breakout; and with Inlet.
OVERBURDEN Worthless or low-grade surface material covering a body of useful mineral. The frozen muck covering dredge gravels in Central Alaska is an example of placer overburden.
OFFSHORE DEPOSITS Mineral deposits on the ocean or sea bottom beyond the low-tide line. See - Marine placer.
PAN 1. A shallow, sheet-iron vessel with sloping sides and a flat bottom, used for washing auriferous gravel or other materials containing heavy minerals. It is usually referred to as a 'Gold pan', but is more properly called a 'Miners'pan'. Pans are made in a variety of sizes but the size generally referred to as "standard" has a diameter of 16 inches at the top, 10 inches at the bottom, and a depth of 2 1/2 inches. Pans made of copper, or provided with a copper bottom are sometimes used for amalgamating gold. 2. (verb) To wash earth, gravel, or other material in a pan to recover gold or other heavy minerals.
PAN FACTOR The number of pans of gravel equivalent to a cubic yard in place. Pan factors vary according to the size and shape of the pan, the amount of heaping when filling the pan, the swell of ground when excavated, and other factors. In practice, factors for a 16-inch pan range from 150 to 200; a factor of 180 is widely used.
PANNING Washing gravel or other material in a Miners' pan to recover gold or other heavy minerals.
PATENT A document by which the Federal Government conveys title to a mining claim. To obtain a mineral patent, the applicant must among other things, (1) make a valid mineral discovery (2) invest $500 in improvements, (3) pay for a boundary survey if lode minerals are applied for, (4) pay $2.50 per acre for the lands in a placer application, or $5.00 per acre for the lands in a lode application. See - Discovery.
PAY DIRT Auriferous gravel rich enough to pay for washing or working. (Fay)
PAY LEAD (pronounced leed) Where gravel is found rich enough to work, and if there is a well-defined bed of it, it is often termed the "pay lead" or, "lead". Compare with Pay streak.
PAY STREAK A limited horizon within a placer deposit, containing a concentration of values or made up of material rich enough to mine. Pay streaks in gold placers are commonly found as more or less well-defined areas on or near bedrock and are commonly narrow, sinuous, and discontinuous. Compare with Pay lead.
PEDIMENT Gently inclined planate erosion surfaces carved in bedrock and generally veneered with fluvial gravels. They occur between mountain fronts and valley bottoms and commonly form extensive bedrock surfaces over which the erosion products from the retreating mountain fronts are transported to the basins. (AGI)
PENEPLAIN A land surface worn down by erosion to a nearly flat or broadly undulating plain; the penultimate stage of old age of the land produced by the forces of erosion. (AGI)
PENNYWEIGHT A unit of weight equal to 24 grains, 0.05 troy ounce or 1.5552 grams. A pennyweight of fine gold has a value of $1.03, with gold at $20.67 per ounce. A pennyweight of fine gold has a value of $1.75, with gold at $35.00 per ounce.
PEPITA (Spanish) A nugget; usually a smaller size.
PERMAFROST Permanently frozen ground in Alaska, up to 100 or more feet in thickness. See - Muck.
PILOT SLUICE A small, auxiliary sluice operated intermittently aboard a dredge to determine the amount of gold being recovered by the dredge during a given interval of time, or from a particular gravel section. The ratio of pilot sluice recovery to dredge recovery is determined for each dredge by empirical means.
PINCHED SLUICE A film-type gravity concentrator employing a wedge-shaped trough, tapering to a narrow vertical opening at its discharge end. In use, heavy-gravity minerals migrate toward the bottom and are removed from the stratified discharge stream by means of splitters. Pinched sluice-type concentrators are used to remove heavy minerals, such as rutile and ilmenite, from beach sands. The CANNON CONCENTRATOR and FANNING CONCENTRATOR are of this type.
PIPE CLAY Miners' term for clays or clay-like materials found in finely-laminated beds within the Tertiary gravels of California's Sierra Nevada region. Some may consist of volcanic material which has fallen into water, in the form of ash, and taken on a stratifiedtorm resembling. clay in appearance.
PIPE FACTOR The depth to which a churn drill casing must be driven to take in a sample volume of 1 cubic yard. For example, a standard 6-inch drive pipe equipped with a new, 7 1/2-inch drive shoe would be driven 88 feet to cut out a theoretical volume of 1 cubic yard. This is sometimes called the CASING FACTOR but it is most commonly known as the DRIVE SHOE FACTOR. See - Radford factor.
PIPER The man operating a hydraulic giant and directing its stream.
PIPING Washing gravel with a hydraulic giant.
PITCH Used in connection with the bedrock in the channel or rim to express decent. (Dunn, R. L.)
PITTING. The act of digging or sinking a pit, as for sampling alluvial deposits. (Fay)
PLACER A place where gold is obtained by washing; an alluvial or glacial deposit, as of sand or gravel, containing particles of gold or other valuable mineral. In the United States mining law, mineral deposits, not veins in place, are treated as placers, so far as locating, holding, and patenting are concerned. (Fay) The term "placer" applies to ancient (Tertiary) gravels as well as to recent deposits, and to underground (drift mines) as well as to surface deposits.
PLACER DEPOSIT A mass of gravel, sand, or similar material resulting from the crumbling and erosion of solid rocks and containing particles or nuggests of gold, platinum, tin, or other valuable minerals, that have been derived from the rocks or veins. (Fay)
PLACER MINING That form of mining in which the surficial detritus is washed for gold or other valuable minerals. When water under pressure is employed to break down the gravel, the term HYDRAULIC MINING is generally employed. There are deposits of detrital material containing gold which lie too deep to be profitably extracted by surface mining, and which must be worked by drifting beneath the overlying barren material. To the operations necessary to extract such auriferous material the term DRIFT MINING is applied. (Fay)
POINT BAR See - Skim bar.
POINTS See - Thaw points.
PROSPECT DRILL See - Churn drill.
PROSPECTING 1. Used to qualify work merely intended to discover a pay lead in a drift mine, or to locate the channel. (Dunn, R. L.) 2. (generally) Searching for new deposits. 3. Drilling a known placer deposit to determine its value or delineate a minable area.
QUATERNARY GRAVELS Gravels deposited from the end of the Tertiary, to and includjng the present time.
QUICKSILVER (or 'Quick). See - Mercury.
RADFORD FACTOR An arbitrary factor used by some engineers in the calculation of drill hole volumes and in turn, the drill hole values. This factor is based on an assumption that due to wear, etc., a 7 1/2-inch drive shoe will take in 0.27 cu. ft. of core per foot of drive instead of the theoretical 0.306 cu. ft. In other words, it assumes a core volume of 1/100 cubic yard per foot of drive. Using this factor, the equation for calculating the drill hole value becomes: value of recovered gold in cents times 100, divided by depth of hole in feet, equals cents per cubic yard. Use of the Radford factor will upgrade the theoretical value by about 12 percent. The Radford factor is sometimes called the KEYSTONE CONSTANT. When reviewing drill logs or reports, care should be taken to determine the factor used. See - Drill factor.
RADIOACTIVE BLACKS A group of dark colored, heavy minerals recovered by placer mining methods in Idaho and elsewhere, and valuable for their contained uranium, thorium, or rare earth components. They include such minerals as brannerite, euxenite, davidite, betafite, and samarskite. See - Rare Earth minerals.
RARE EARTH MINERALS A group of widely distributed but relatively scarce minerals containing rare earth compounds, usually in combination with uranium, thorium, and other elements. Monazite and other rare earth minerals are obtained from placers in Idaho, and elsewhere. See - Monazite; also Radioactive blacks.
R/E See - Recovery.
RECOVERY 1. The amount or value of mineral recovered from a unit volume; in the case of gold placers, expressed as cents per cubic yard. 2. The amount of mineral extracted, expressed as a percentage of the total mineral content. 3. In gold dredging, the expression "R over E" (designated R/E) is used to compare actual recovery to expected recovery where R represents the actual returns and E represents the estimated recoverable value, after allowing for known or expected mining and metallurgical losses, etc. When recovery exceeds the initial estimate, the R/E will be shown as something greater than 100%, such as 105%, 110%, etc.
REPRESENTATIVE SAMPLE See - Sampling.
RESIDUAL PLACER Essentially, an in situ enrichment of gold or other heavy mineral, caused by weathering and subsequent removal of the lode or other parent material, leaving the heavier, valuable mineral in a ~omewhat concentrated state. In some cases, a residual placer may be essentially an area of bedrock, containing numerous gold-bearing veinlets that have disintigrated by weathering to produce a detrital mantle rich enough to mine. In some parts of California, such areas are known as SEAM DIGGINGS.
RETORT A vessel with a long neck used for distilling the quicksilver from amalgam. (Fay)
RIFFLE 1. The lining of a bottom of a sluice, made of blocks or slats of wood, or stones, arranged in such a manner that chinks are left between them. The whole arragement at the bottom of the sluice is usually called THE RIFFLES. In smaller gold-saving machines, as the rocker, the slats of wood nailed across the bottom are called RIFFLE-BARS, or simply RIFFLES. (Fay) 2. A groove in the bottom of an inclined trough or sluice, for arresting gold contained in sands or gravels. (Fay) 3. A shallow extending across the bed of a stream; a rapid of comparatively little fall. (AGI)
RIM ROCK (or RIM) The bedrock rising to form the boundary of a placer or gravel deposit. (Fay)
RIVER-BAR PLACERS Placers on gravel flats in or adjacent to the beds of large streams. (Brooks)
RIVER MINING The mining of part or all of a river bed after by-passing the stream by means of flumes or tunnels; or by use of wing dams to divert the river from the working area.
ROCKER A short, sluice-like trough fitted with transverse curved supports, permitting it to be rocked from side to side, and provided with a shallow hopper at its upper end. The hopper bottom consists of a punched-metal plate containing holes about Y4-inch or %-inch diameter. This is for the purpose of holding back the larger rocks which when washed, are discarded. A flow of water, aided by the rocking motion, carries the fine material down the trough where the gold or other heavy minerals are caught by riffles. Rockers are generally operated by hand but large, power· driven rockers are sometimes employed. When washing chum drill samples, rockers are often used without riffles, the recovery being made on the smooth wooden bottom much in the manner of panning. CRADLE is an obsolete term for rocker.
ROCKING The process of washing sand or gravel in a rocker.
ROUGH GOLD Gold that has not been appreciably worn or smoothed by movement and abrasion. It may be more angular than rounded and may have included or attached quartz particles. As a rule, rough gold is found near its place of origin.
RUBEL ELEVATOR (pronounced Roo-bull) A form of elevator used in hydraulic mines, particularly those having insufficient bedrock grade for effective tailings disposal. It is essentially a large, inclined flume, through which gravel or tailings are driven by a strong water jet furnished by a hydraulic giant. A grizzly arrangement removes the fines for treatment in conventional sluices while the rocks are discharged from the upper end.
RUSTY GOLD Free gold, that does not readily amalgamate, the particles being covered with a silicious film, thin coating of oxide of iron, etc. (Fay)
SALTING 1. Intentional salting. The surreptitious placing of gold or other valuable material in a working place or in a sample to make it appear rich in mineral. It is done with intent to defraud. 2. Unintentional or innocent salting. The unintentional or accidental enrichment of a sample through erroneous procedure or carelessness, without intent to defraud.
SAMPLE A portion of the ore systematically taken, by which its quality is to be judged. (Fay)
SAMPLING Cutting a representative part of an ore deposit, which should truly represent its average value. Honest sampling requires good judgement and practical experience. (Fay) Parenthetically, it should be noted that in the case of gold placers, the high unit-value of gold, its extreme dilution within the gravel mass and its typically erratic distribution are factors which individually or combined, make it virtually impossible to obtain a truly representative sample. To this extent, the usual definitions of sampling do not apply to gold placers.
SAND PUMP A special plunger-type vacuum pump used to remove the chopped-up drill core from a churn drill hole.
SAUERMAN EXCAVATOR See - Slackline scraper.
SCALY GOLD Small, rounded, flattened gold particles; usually quite thin in proportion to their diameter.
SCHIST A crystalline rock that can be readily split or cleaved because of having a foliated or parallel structure. (Fay) Schist bedrocks, because of their rough, platy structure, generally make excellent gold catchers.
SCHISTOSE Characteristic of, resembling, pertaining to, or having the nature of schist. (Fay)
SEA-BEACH PLACERS Placers reconcentrated from the coastal-plain gravels by the waves along the seashore. (Brooks)
SEAM DIGGINGS (California) Residual deposits consiting of decomposed bedrock filled with irregular seams of quartz containing gold. In California, seam diggings have been worked by the hydraulic method.
SECOND-FOOT A unit of water measurement equivalent to one cubic foot per second or 448.83 gallons per minute. Commonly used to report the flow of streams.
SELF-SHOOTER See - Booming.
SHAFT FACTOR A correction factor applied to drill-hole values after a shaft has been sunk over the drill hole. The factor is based on the difference in values obtained from the drill hole and from the shaft; the shaft value generally being considered the more reliable of the two.
SHINGLE 1. The flatter pebbles and cobbles in a stream deposit will often come to rest with their uppermost edge leaning slightly down-steam. This 'shingling' effect is used by placer miners to determine the direction of flow of ancient streams and it can be particularly useful when working drift mines. 2. Beach gravel, especially if consisting of flat or flattish pebbles.
SHOE FACTOR See - Drive Shoe factor.
SHOTTY GOLD Small granular pieces of gold resembling shot. (Fay) Any small, more or less rounded gold particle that is somewhat equidimensional rather than platy.
SICK MERCURY See - Floured mercury.
SKIM BAR An area near the upstream end of an accretion bar from which superficial concentrations of flood gold are mined by 'skimming' off a thin layer of gravel. They are sometimes known as POINT BARS, probably because of their proximity to the upper point of the accretion bar. See - Flood gold; also Accretion bar.
SKIN DIVING The use of wet-type diving suits, with or without self-contained underwater breathing apparatus. Skin diving gear is generally used by the operators of small hydraulic dredges and by divers who search for underwater bedrock crevices from which gold-bearing materials may be retreived. See - Jet dredge.
SLACKLINE SCRAPER Consists essentially of a head tower and a movable tail tower or tail block, supporting a track cable. A bucket or scraper running along the track cable can be raised and lowered by tightening or slackening the track cable. The digging bucket or scraper runs out by gravity and is pulled in by a drag cable. The hoisting machinery and in some cases a screening or washing plant are incorporated in the head tower. This arrangement is also known as a CABLEWAY SCRAPER. The SAUERMAN EXCAVATOR is of this type.
SLATE A fine-grained rock formed by the compression of clay, shale, etc., that tends to split along parallel cleavage planes and to form a rough, platy bedrock, well suited for the retention of placer gold.
SLICKENS A word sometimes used to designate the finer-size tailings, or mud, discharged from a placer mine. Sometimes synonymous with Slime.
SLUDGE The fluid mixture of chopped up core and water that results from the drilling action in a churn drill hole. When the sludge is pumped from the hole, it becomes the sample for the particular section of hole that produced it.
SLUICE BOX An elongated wooden or metal trough, equipped with riffles, through which alluvial material is washed to recover its gold or other heavy minerals. Small sluice boxes are commonly, but erroneously, called "Long Toms".
SLUICEPLATE A shallow, flat-bottomed steel hopper arrangement at the head-end of a sluice box. A bulldozer is generally used to push gold-bearing gravel onto the sluiceplate, from where it is washed into the sluice by water issuing from a large pipe or by means of a small hydraulic giant.
SNIPER An individual miner, usually a transient, who gleans a living from gravel remnants not worth working except by someone content with very modest gains. He usually works with simple hand tools and washes his gravel in a short sluice or dip box. Being transient and generally innocuous, he seldom owns or leases the land he works.
SODIUM AMALGAM Mercury that has been treated with small amounts of metallic sodium to increase its affinity for gold and other metals.
SPECIFIC GRAVITY The specific gravity of a substance is its weight as compared with the weight of an equal bulk of pure water. For example, placer gold with a specific gravity of about 19 is 19 times heavier than water. The specific gravity of a mineral largely determines its susceptibility to recovery in simple gravity concentrators such as sluice boxes.
SPECIMEN GOLD Nuggety gold or other forms suitable for the manufacture of natural-gold jewelry or for display purposes.
SPIRAL CONCENTRATOR A wet-type gravity concentrator in which a sand-water mixture, flowing down a long, spiral shaped launder, separates into concentrate and tailings fractions. The concentrates are taken off through ports while the tailings flow to waste at the bottom. The HUMPHREYS SPIRAL, which employs this principle, is widely used for recovering heavy minerals from beach sands.
SPONGE The somewhat porous mass of gold remaining after the mercury has been removed from a gold amalgam by heating.
SPOON A shallow, oblong vessel, at one time made from a section of ox horn but now made of metal. Used to test small samples of gold-bearing material by washing, in a manner similar to panning. More properly called a MINERS' SPOON or, HORN SPOON.
SPOTTED GRAVEL Where gold is erratically distributed through a deposit, the term "spotted" or, "spotty"gravel is sometimes applied to it.
STRIP To remove the overlying earth, low-grade, or barren material from a placer deposit.
STRUCK CAPACITY Level-full, that is, the capacity of a container filled even with its rim or top.
SUBMARINE PLACER See - Marine placer.
SUCKER 1. A syringe used to remove material fJOm underwater crevices in the bedrock. 2. A small, hand-held jet dredge of the type carried underwater.
SUCTION DREDGE See - Hydraulic dredge; also Jet dredge.
SUCTION LIFT The vertical distance from the level of the water supply to the center of a pump, to which must be added the loss due to friction of the water in the suction pipe.
SURF WASHER A small sluice, somewhat similar to a long tom; used to recover gold from beach sands. The surf washer is placed so the incoming surf rushes up the sluice, washing material from a hopper and upon retreating carries it over the riffles.
SWELL The expansion or increase in volume of earth or gravel upon loosening or removal from the ground. The average swell of gravel is around 25% and sometimes as high as 50%.
TAIL (verb) Manipulating the concentrate product in a gold pan in such a way that the heavier minerals and in particular the gold colors string out in the bottom of the pan in a long, narrow "tail", where they can be readily inspected or counted. This is referred to as "tailing a pan. "
TAILINGS The washed material which issues from the end of a sluice or other recovery device in a placer operation. The tailings from hydraulic mines are generally referred to as "debris" in legislative documents.
TENOR The percentage or average metallic content of an ore. (Fay) As commonly used, it is synonymous with an approximate, or a general value rather than a precisely known value.
TERRACE A relatively flat, and sometimes long and narrow surface, commonly bounded by stcep upslopes and downslopes on opposite sides. Gravel terraces may be stepped, and they are commonly dissected by transverse drainage patterns.
TERTIARY The earlier of the two geologic periods comprised in the Cenozoic era, in the classification generally used. Also, the system of strata deposited during that period. (AGI)
TERTIARY CHANNELS Ancient gravel deposits, often auriferous, composed of Tertiary stream alluvium. Tertiary gravels are abundant in the Sierra Nevada gold belt of California where many have been covered by extensive volcanic eruptions and subsequently elevated by mountain uplifts, and are now found as deeply-buried channels, high above the present stream beds.
TEST PIT See - PITTING.
THAW POINTS Water pipes driven into frozen gravel, through which water at natural temperature is ciculated for weeks or months, to thaw the ground ahead of dredging. Where used in Alaska, points are usually spaced 16 feet apart. Once thawed, the ground does not freeze again and thawing is usually carried one or two seasons ahead of the dredge.
TIGHT GRAVEL A hard, or compact gravel that is not cemented, but requires something more than normal effort to excavate. Compare with CEMENTED GRAVEL.
TILL Nonsorted, nonstratified sediment carried or deposited by a glacier (AGI)
TOP WASH A deposit of gravel, not in a channel on the bedrock, but resting on cement overlying the bottom deposit. (Dunn, R. L.)
TRACE A very small quantity of gold; usually a speck too small to weigh. In reporting samples it is abbreviated tr.
TRESTLE SLUICE A moveable steel sluice constructed on a skid or track-mounted trestle; usually provided with a hopper, grizzly and wash water system, and fed by a dragline or similar excavator. Also called an ELEVATED SLUICE.
TROMMEL A heavy-duty revolving screen used for washing and removing the rocks or cobbles from placer material prior to treatment in the sluices, gold-saving tables, or other recovery equipment.
TROY OUNCE The one-twelfth part of a pound of 5760 grains; that is 480 grains. It equals 20 pennyweights, 1.09714 avoidupois ounces, 31.1035 grams, or 31,103 milligrams. This is the ounce designated in all assay returns for gold, silver or other precious metals. (Fay)
TUNNEL The nearly horizontal excavated opening from the surface into the mine. (Dunn, R. L.)
UNDERCURRENT A large, flat, broad, branch sluice, placed beside and a. little lower than the main sluice. This apparatus is riffled like the sluice, but being much wider than the latter, allows the water to spread out in a thin sheet over its surface, thereby so abating the velocity of the current that the very fine gold, including the rusty particles, is more apt to be caught here than in the sluice. (Fay) Undercurrents are usually fed with fine-size material taken from the main sluice by means of a grizzly placed in the sluice bottom, near the discharge end.
UPPER LEAD (pronounced leed) A pay lead in a top wash or in the gravel deposit considerably above the bedrock. (Dunn, R. L.)
VALUES The valuable ingredients to be obtained, by treatment, from any mass or compound; specifically, the precious metals contained in rock, gravel, or the like. (Fay)
VOLUME FACTOR The volume of sample which should be taken into a churn drill casing for each foot of drive. For example, a standard 6-inch drive pipe equipped with a new, 7Yz-inch drive shoe will theoretically take in a volume of 530 cubic inches, or, 0.306 cubic foot per foot of drive. See - Core factor; Drive shoe factor; Drill factor.
WARD DRILL A lightweight, hand-powered churn drill widely used in South America, particularly in remote areas where access is difficult and manpower is cheap. The drilling tools are suspended from a tripod and the reciprocating motion provided by a simple spudding arm known as a "Diablo". Sometimes referred to as a HAND DRILL.
WASH 1. A Western miners' term for any loose, surface deposits of sand, gravel, boulders, etc. 2. The dry bed of an intermittent stream, sometimes at the bottom of a canyon. Also called Dry wash. 3. To subject gravel, etc. to the action of water to separate the valuable material from the worthless or less valuable; as to wash gold. (Fay) In drift mining (California), the term "Wash" is used indifferently in describing channel gravel, volcanic mud flows, or masses of lava boulders. (Dunn, R. L.)
WASTE Valueless material such as barren gravel or overburden. Material too poor to pay for washing.
WATER TABLE The upper limit of the portion of the ground wholly saturated with water. This may be very near the surface or many feet below it. (Fay)
WEATHERING The group of proccsses, such as the chemical action of air and rain water and of plants and bacteria and the mechanical action of changes of temperature, whereby rocks on exposure to the weather change in character, decay, and finally crumble into soil. (Fay)
WING DAM A dam built partially across a river to deflect the water from its course. (Fay) See - River mining.
WING FENCE A V-shaped wall, usually made of heavy timber and attached to the head of a sluice and arranged to guide gravel into the sluice as it is swept from the pit by a hydraulic giant.
YARDAGE 1. The number of cubic yards of gravel mined or put through a washing plant in a shift or a day. 2. A measured block of gravel.
YIELD The quantity or gross value of minerals extracted from a deposit. YOUTH. See - Erosion cycles.
ZIRCON A mineral of widespread occurrence as small crystals in igneous rocks. Composition, zirconium silicate, ZrSiO4 Because of its resistance to weathering, and moderate specific gravity (4.68), zircon is a common constituent of a black sands associated with gold placers.
