Mining Glossary

AMALGAMATION
A process used to separate gold from the ore. The ore is crushed in a mercury-water solution and subjected to violent agitation. This motion breaks up the mercury into minute particles, which adhere to the gold. Later, when the gold has partially separated from the mercury, the remaining mass is heated in a retort. The mercury leaves in the form of a vapor, which is condensed and used again. The gold is now almost pure and is cast into bars.

ARRASTRA

A primitive method of using mule power to crush the ore. This method required a shallow, paved, circular pit, with a sturdy rotating post set in the center to which heavy beams were attached. The beams were in turn hooked to large wheels of stone. Ore was dumped into the arrastra and mixed with water. Mule-power was used to rotate the apparatus, reducing he ore to a muddy mass. Panning or amalgamation could then separate the gold.

ASSAY OFFICE
A place that will assay, or evaluate, the mineral content of any ore by a chemical or other analysis.

BAR
Pertaining to rivers. Generally know as a bank of sand, gravel, or rock. The word was used as the last part of any camp that happened to spring up along a river bar.

BULLION
Gold or silver that has not been minted, usually stored in the shape of bricks or bars.

DIGGINGS
A term used by many of the early miners when referring to a claim that was being worked or mined for gold.

DREDGING
This process consists of a barge or boat equipped with machinery that scoops the rich gold-bearing gravel from the riverbeds and is then processed by washing or sluicing. It was used extensively in gold-bearing the rivers of the west.

DUST
A term used to describe minute particles of gold taken from the placers. This ‘dust’ was used as money. In many of the camps, a dollar in dust was the amount that could be held between the thumb and forefinger. This was called a ‘pinch.’ A whiskey glass was used to measure $100.00.

FLUME
An inclined channel usually constructed of wood or stone, used to convey water for along distances. A narrow gorge or ravine may also be used for the same purpose is sometimes referred to as a flume.

GIANT MONITORS
The name given the huge nozzles, which shot large jets of water, that washed away mountains and towns in the search for rich, gold-bearing gravel. See Hydraulic Mining.

GLORY HOLE
This term was applied by the early miners to an unusually rich but small deposit of gold-bearing ore.

GULCH
A narrow and deep ravine or valley. In some instances camps were named with the word gulch as part of the name, such as Quartz Gulch.

HARDROCK MINING
An underground method of mining often accomplished by sinking a shaft over the vein or pocket of ore, with drifts, or tunnels, running out from the various levels. Some of the larger mines ran up to 10,000 feet deep, with several miles of drift. Tremendous investments were necessary besides the labor expense in sinking the shaft: Stamp mills had to be built, tanks had to be constructed to store the chemicals used in the process, and equipment was needed to raise the ore from such tremendous depths.

HYDRAULIC MINING
This method of mining consisted of concentrating powerful jets of water upon a specific area, washing the gold-bearing earth or gravel into a sluice. Ridges in the bottom of the sluice saved the dust and allowed the mountains of earth to pass into thee creeks and rivers. The dirt eventually caused a navigation hazard in major rivers and San Francisco Bay, which led to a law prohibiting hydraulicing.

NUGGET
A lump of native gold of no special size, but usually bigger than the head of a match. The largest nugget ever found in the United States weighed 195 pounds.

PANNING
A method of extracting gold from streambeds. A saucer-shaped pan is partially filled with gravel and dipped in water. The pan is then moved gently in a circular motion to wash out the lighter gravel. The gold, being heavier, sinks to the bottom and remains.

PLACER CLAIM
Any mining claim that has been located or ‘staked out’, over a mineral deposit. These placer deposits were built up over the ages through the erosion process, which is why most claims were located along rivers, creeks and dry streambeds.

PLACER MINING
The process of gathering the precious metals from the claim. This was accomplished by several different methods, of which the best known and most commonly used were: panning, hydraulicing, dredging and other variations of sluicing, glory hole mining and tunneling. Because of the importance of water in all of these process, the placer claim was usually located on or near as possible to a stream. In many instances rich placer claims were located high and dry, and water was brought in by flume and ditch to complete the process.

POCKET
A mining term referring to a small but rich concentration of gold located in a quartz vein. This term, applied to placer mining, generally means a low spot or hole in a streambed that has captured the dust and nuggets.

POKE
A crude leather pouch equipped with a drawstring. The miners used them to store or carry gold dust and nuggets.

QUARTZ
A very common, hard mineral, sometimes found in brilliant crystals but generally found in large masses or veins. Many semi-precious stones are forms of quartz; however, most quartz is mined for its gold content. See Hardrock.

RETORT
A furnace used to heat the mixture of gold and mercury. The mercury is passed off in a vapor and saved; the gold is then formed into bars.

ROCKER
A crude machine used mainly by the Chinese in working the placers, This contraption consisted of a sieve-bottomed hopper mounted on a rocker. Water and earth were fed into the hopper as the machine was rocked. The rocking motion washed the earth through the sieve onto a slanting apron. Ridges lining the bottom of the apron trapped the gold and allowed the lighter gravel and earth to be washed out.

SLUICING
This method of extracting gold from the rich placer claims consisted of a long inclined series of troughs (sluice boxes) to which riffles or slats were fixed across the bottom. Gold-bearing earth or gravel and water were fed into the sluice at the upper end. The water was regulated to carry the earth over the riffles and out, allowing the heavier gold to settle and be trapped by the riffles. Quicksilver (mercury) was sometimes placed behind the riffles to catch the gold.

SNIPER
The name given to a person who prospects over old ‘diggings’ or small crevices looking for gold.

STAMP MILL
A mill that breaks and grinds the gold-bearing ore, saving the gold by means of amalgamation.

STRIKE
A term applied to the finding of a new concentration of gold rich enough to be mined profitably.

TAILINGS
The waste left after gold-bearing ore or gravel has been processed.

TAILING WHEELS
The huge wheels, sometimes 50 feet in diameter, used to transport tailings from the mill to a dump. The dump was usually located away from the mill to prevent the ever-growing mountains of waste from cluttering and isolating the mill-site.

VEIN
A term referring to a regularly shaped and lengthy occurrence of an ore.