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El Capitan - Precious metals index Category: Agriculture and Industry > Gold and silver Date & country: 07/03/2016, USA Words: 86

Magma
see Igneous rock.

Matrix
the rock that contains minerals or ore.

Magnetite
the mineral form of black iron oxide, often found with magnesium, zinc, and manganese. An ore of iron. Also known as black sand.

Lode
an irregular vein; a mineral deposit or vein, often without well-defined walls. Therefore, a gold lode deposit is a primary deposit of gold in a vein.

Leach
dissolving metals from ore by draining a solution intended to place the minerals in solution.

Lode claim
claims of valuable minerals in classic veins or lodes having well defined boundaries and imbedded in other rock, they may be claims of broad zones of mineralized rock. Load claims are generally parallelograms with the long sides parallel to the vein or lode. They are limited by statute to a maximum of 1,500 feet in length along the vein and 300 feet on either side. Typically, lode claims become a tunnel site.

Knob
a prominent or isolated rounded hill or mountain with steep sides.

Karat
denotes the proportion of solid gold in an alloy based on a total of 24 parts. For example, a 14-karat (14K) gold designation indicates a composition of 14 parts of gold and 10 parts of other metals.

High banker
a term for any operation of a sluice box above a streambed on a high bank of stratified gravels and dirt paralleling a watercourse. High bankers usually operate with a gasoline-powered pump. High bankers are often used on ancient brownish-stained composites that indicate concentrations of minerals and black sand, or whitish to rust-colored quartz gravels in layers apart from the rest of the deposit, or any rounded gravel layer that is distinct from the predominant material, all are conditions that are favorable for gold placers. See black sand.

Igneous rocks
formed by solidification from a molten state (magma), or cooled at great depths (plutonic rocks), or blown into the air as rock fragments (volcanic rocks).

Hardpan
bolder clay or layers of cemented gravel.

Gulch
a narrow ravine or small canyon.

Grain
a unit of weight equal to 0.0648 part of a gram, 0.04167 part of a pennyweight, or 0.002083 part of a troy ounce. There are 480 grains in a troy ounce.

Gold float
fine gold floats on the water surface in panning or other concentration operations, especially if contaminated with oil, grease or clay.

Gold lode
a vein of gold.

Ground slucing
a method of mining gravel by water not under pressure. Typically a natural or artificial water channel is directed through a channel or cut of placer material. The material may be run over a sluice box or allowed to accumulate on bedrock for subsequent concentration.

Gram
a unit of weight in the metric system equal to 15.432 grains, 0.643 pennyweight, or 0.3215 troy ounce. There are 31. 003 grams in a troy ounce.

Gold mining vacuum
see Vacuum, gold mining.

Gold pan
a miner's pan made of metal or plastic used to concentrate placer gold.

Gold placers
sand or gravel that containing gold nuggets, and/ or gold as course, medium, fine, very fine and flower gold. Gold placers may be at or near the surface, but are usually below some overburden.

Gold dust
once a common term for placer gold, particularly fine gold.

Gold, course
gold that remains on a 10-mesh screen.

Gold, fine
gold that passes a 20-mesh screen and remains on a 40-mesh screen.

Gold suckers
a hand operated device used to suck-up gold placers from between cracks and crevices and off river or stream bedrock. They typically consist of an outer and inner tube, O-rings and a crevice sucker attachment. Several commercial models are available. Plans are available for gold sucker construction.

Gold, medium
gold that remains on a 20-mesh screen and passes a 10-mesh screen.

Gold, very fine
gold that passes a 40-mesh screen.

Gold, flower
see Flower gold.

Flagget
a term created to identify a piece of gold bigger than a flake but smaller than a nugget.

Formation
the common local rock in which an orebody is found. Several formations in a region make a system of rocks.

Fossil placers
gold placer deposits that have been cemented into hard rock by geological processes.

Fool's gold
a material that superficially resembles gold, usually a form of pyrite, an iron sulphide, FeS2.

Free gold
gold not in combination with any other substance.

Float
the loose or scattered pieces of ore broken off from a vein outcrop. Float may be traced to its source or outcrop by prospecting.

Fine gold
gold too small to be found by almost all metal detectors, requiring panning or some other method of concentration.

Flow lines
lines of crystals, mineral streaks, or inclusions in an igneous rock that indicate the direction of flow before consolidation.

Floatation
a process of concentration whereby crushed ore is mixed with water and oil or chemicals, the minerals, like gold and silver, float while the worthless material sinks.

Fineness
the degree of purity of gold, either native, bullion or refined gold, stated in terms of gold content in parts per thousand. A gold nugget containing 895 parts of pure gold and 105 parts of other metals, such as silver and copper, would be considered 895 fine.

Fissure
a crack or opening in rocks; fissure veins are those formed by mineral matter being deposited in the cracks.

Dragline dredge
a machine that consists of a self-propelled power shovel fitted with a dragline bucket and a floating plant to process the material dredged. See Dredge.

Erosion
weathering and movement of rocks and debris.

Escarpment
a steep slope or cliff formed by the erosion or separation of two relatively level areas of differing elevations.

Face
any part of a mine where work is under way.

Drift-gravel
gold-bearing gravel lying on granite usually with overburden.

Drift
A horizontal underground passage driven along or parallel to a vein. Also a secondary passageway between two main shafts or tunnels.

Draw
a small natural gully or other watercourse, usually part of a dry streambed.

Dredge
a machine, operated by some form of power, usually mounted on a flat-bottomed hull equipped to dig, process and dispose of alluvial or other placer gravels from the bottom of rivers or other bodies of water.

Dirt
the miner's term for auriferous gravel or the material being worked. See Pay dirt.

Dry digging
mining operations in dry gulches not associated with a river or stream. See Wet diggings.

Dry washer
a device for recovering gold or other heavy minerals from dry alluvial material without the use of water. Typically a hand powered device with a sloping riffle board and a bellows or blower. The bottom of the riffle board is made of some porous material to trap the gold or mineral. Air forced through the bottom by the bellows or blower causes the lighter materials to be expelled over the riffles and out the machine, while the gold or heavy mineral is trapped in the porous material on the riffle board.

Deposit
enough mineral in rock to make an ore.

Develop
open a mine and ore; search, prospect, explore.

Cyanide process
a process of gold extraction based on gold's solubility in sodium or potassium cyanide. Caution: cyanide solutions are poisonous, handle with care!

Confluence
a junction of streams.

Concentrate
the valuable minerals separated from the containing rock or gravel by any process of concentration.

Colloidal gold
gold in an extreme state of subdivision; in a true colloidal gold suspension the gold is almost in a molecular form.

Crevicing
the removal of placer material from the cracks and crevices in bedrock.

Cradle
see Rocker box.

Conglomerate
an aggregate of rounded and water-warn pebbles and boulders cemented together.

Concentration
the removal by some mechanical means of the lighter material in an ore or placer material.

Contact deposit
one between two unlike rocks, usually applied to an orebody at the contact between a sedimentary rock and an igneous rock.

Contour
The outline of the surface of the ground with respect to its undulation. Topographic maps of the U. S. Geological Survey show contour lines.

Core
see Drill core.

Contiguous
in actual contact or near though not in actual contact, as in mining claims.

Classifier screens
used to sort out gravels and other gold placers by the size of the material that stay on top of and go through screens of varying sizes. Often classifier screen buckets are used with rocker boxes and sluices to pre-classify gold placers.

Claim
the filing of appropriate documents to establish ownership of a lode or placer mining operation.

Channel
gravel in a river, stream, canyon or gulch, often with overburden.

Caliche
a soil type common in the West and Southwest containing excessive amounts of calcium carbonate. Caliche soils may be thin or a dozen or more feet thick and can be extraordinarily hard. Caliche placers present significant mining challenges.

Black sand magnet
a magnet used to remove black sand from concentrates.

Black gold
alluvial gold coated by black oxide of manganese.

Black sand
heavy grains of magnetite, chromite, ilmenite, cassiterite or tourmaline found in rivers, beaches, canyons, gulches and (unfortunately) sluice-boxes. Often black sands are associated with gold placers.

Buried placers
placer gravels covered with some other strata or overburden.

Bullion
unrefined gold and/ or silver mixtures that have been melted and cast into a bar.

Auriferous
containing gold.

Bar
a bank of sand, gravel or other material at the mouth of a river; or similar gold-bearing material in the slack portion of a stream.

Base metals
all the useful metals except the precious metals.

Bedrock
any solid rock underlying auriferous gravel and upon which the gold rests.

Benches
ledges of all kinds of rock or gravel shaped like steps or terraces. Bench placers are usually 50 to 300 feet above the present streams.

Attrition
the act of rubbing together, friction; abrasion.

Assay value
the amount of gold, silver or other metal contained in an ore or other material as determined by assay of a sample of that material.

Assay
the determination of the amount of metal contained in an ore.

Amalgamation
the mixing or grinding of clean mercury with gold concentrates. Sometimes included the addition of lye, dilute nitric acid or a weak cyanide solution. The combined product is called an amalgam. An amalgam requires the separation of the mercury from the gold. Excess mercury can be removed by passing and squeezing the amalgam material through a muslin or canvas sack. The remaining amalgam is heated or dissolved in nitric acid to remove the mercury. The remaining residue is gold.Caution

Aqua regia
a mixture of one volume of concentrated nitric acid and two volumes of hydrochloric acid. Used to put gold into solution.

Amalgam
an alloy of mercury with gold or another metal. See Amalgamation.

Alkali fusion
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. It is also defined as a base that dissolves in water. Alkali fusion is applied to substitute a sulfonic acid group with a hydroxyl group in a substituted aromatic ring. Beside the main reaction, also side reactions appear, because the substituents in the aromatic ring are eliminated and the aromatic rings are polymerized. A kinetic model for the main and the side reactions in alkali fusion of a substituted aminobenzenesulfonic acid was developed. The substitution reaction of sulfonic acid with a hydroxyl group, the elimination of sulfonic acid and amino groups, the dealkylation reactions, and the polymerization reactions were included in the kinetic model.

Alluvial deposit
clay, silt, sand, gravel, gold or other mineral or other unconsolidated material deposited gradually by flowing water.

Adit
An entrance to a mine that is essentially horizontal. This is commonly called a tunnel, although strictly a tunnel is open at both ends.