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Visit our on-line presentation of the "Modern Gold Dredge" by Bruce Harris. This includes a great Gold Mining Dictionary.
This definition glossary is an exerpt from the "Modern Gold Dredging©" series of books and is provided for our web site's visitors & customers personal enjoyment. Copyright© 1992 by HMMC. All rights reserved worldwide.
GLORY HOLE: A bedrock hole or pothole, containing or suspected of containing large amounts of gold.
GOLD BULLION: Unrefined gold that has been melted and cast into a bar. In placer mining, the gold sponge obtained by retorting is commonly melted with borax or other fluxes, then poured into a bullion bar.
GOLD DUST: A loose description of small pieces and particles of gold. Commonly a mix of unseparated sizes, generally considered anything under #16 mesh. This size of gold, is commonly found in flood gold deposits along gravel bars and the outside of bends in a waterway.
GOLD ROUTE: The general path(s) which gold takes, during its movement by water action though a given section of waterway; the general line of gold's travel.
GOLD VEIN: A gold bearing fissure or streak in bedrock or Tertiary deposits that contains lode gold. Sizes range from small microscopic particles, to hundred pound nuggets, and may suddenly change to a "pocket" concentration at any time.
GRADE: 1. The amount of fall or inclination from the horizontal in ditches, flumes, or sluices; usually measured in inches fallen per foot of length or inches fallen per section of sluice. 2. The slope of land or bedrock surface; usually measured in percentages. A 1% grade is equivalent to a rise or fall of 1 foot per 100 feet. 3. The slope of a stream or any surface over which water flows; usually measured in feet per mile. Streams having grades of about 30 feet per mile, favor the accumulation of placers, particularly where a fair balance between transportation and deposition is maintained for a long time. 4. The relative value or tenor of an ore or of a mineral product.
GRADED STREAM: A stream in equilibrium, that is, a stream or a section of a stream, that is essentially neither cutting or filling its channel.
GRANITE: A coarse-grained, hard igneous rock commonly found everywhere in mountainous regions. The rock consists mainly of quartz, orthoclase or microline, feldspar, and mica. Granite is the most common bedrock in the Sierra Nevada mountain range.
GRAVEL: A comprehensive term applied to the water-worn mass of detrital material making up a placer deposit. Placer gravel are sometimes arbitrarily described as fine, heavy, large, small, boulder gravel, etc.
GRAVEL BAR: See "bar placer."
GRAVEL PLAIN PLACERS: Placers found in gravel plains that formed where a river canyon flattened and widened or, more often, where it entered a wide, low gradient valley.
GULCH PLACER: A somewhat direct accumulation of materials, washed down from the immediate surrounding hillsides into a waterway, where the streambed allows for it.
GUTTER: The lowest portion of an alluvial deposit; commonly a relatively narrow depression or trough in the bedrock or the bedrock itself. In some placers the "pay streak" is largely confined to a narrow streak or "gutter."
HANG-UP: Generally rough bedrock or false bedrock that has caught and collected some gold or other heavy minerals.
HARDPACKED MATERIALS: These are materials which have been cemented together naturally. Though this is not a true indication of a virgin bed, it does indicate it has been laid down for some time. If found as a layer it would be called a "hardpan."
HARDPAN: A layer of hardened or cemented gravel found underlying a storm layer in a waterway. This gravel is cemented mainly with clay, but can be any calcareous, siliceous, or ferruginous material. These can be found spotty or cover large sections of the streambed and may be found with one or more of them overlying bedrock.
HARDROCK MINING: Same as "lode mining."
HEAVY GOLD: High purity gold in compact pieces, that weigh heavy in proportion to their size. Most often nugget gold.
HEAVY MINERALS: The accessory detrital minerals of a sedimentary rock with a high specific gravity. The "black sand" concentrate common to placers, would more properly be called a "heavy mineral."
HEMATITE: The chief ore of iron (Fe2O3, 70% iron), having a blackish-red to brick red color. In water or when wet they look black in color; see "black sands."
HIGH-GRADE: 1. Rich ore. A term applied to ores rich in the values they are mined for. 2. To steal or pilfer ore or precious metals, as from a mine by a miner.
HIGH PRESSURE AREA: A "high pressure area" is a general term referring to a place where water is moving fast, in comparison to the main flow of water. Low-pressure areas can be of any size and are classified into three categories to clarify a particular size; large, medium and small.
HILLSIDE PLACERS: A group of intermediate gravel deposits between creek and bench placers. Their bedrock is slightly above the creek bed, and the surface topography shows no indication of benching.
ILMENITE: Titanium ore (FeTiO3), having a lustrous black to brown color; see "black sands."
IMPURITY: Something that is not pure. Gold is the best example of this, because both lode and placer gold will be found to contain impurities; such as silver & copper. Raw-gold needs to be processed, to extract these impurities, to become pure gold; bullion.
INLET: The point where a channel is cut off by a ravine or canyon on the upstream end. Usually applied to buried Tertiary channels.
IRON SAND: 1. Magnetite or ilmenite rich sand. 2. Black sand concentrate containing an abundance of magnetite.
JEWELRY GOLD: Good-sized pieces of gold that are of proper quality to be used in the jewelry making trade; 1. Nuggets with quartz still attached, or quartz with gold showing that could be used for jewelry, called either "gold quartz" or "jewelry quartz." 2. Oddly shaped or unusual nuggets of placer gold. 3. Small size gold.
LARGE HIGH PRESSURE AREA: A "high pressure area" the size of an entire section of waterway; generally a few miles long or more. Also called "major high pressure areas." See "high pressure area."
LARGE LOW PRESSURE AREA: A "low pressure area" the size of an entire section of waterway; generally a few miles long or more. See "low pressure area."
LAVA: The term "lava" as used by a placer miner may designate any solidified volcanic rock, including volcanic agglomerates.
LEAD: See "pay dirt."
LIGHT GOLD: Gold that is in very thin flake form that looks large compared to its weight and could easily be moved during flood conditions.
LODE: These are gold bearing veins or pocket gold found in or upon exposed bedrock or as an ore; rock formations containing particles of gold, that may or may not be in chemical combination with other minerals.
LODE MINING: The mining of lode deposits. Also called "hardrock mining."
LOOSE-PACKED MATERIALS: This would be materials which are not cemented together or hardpacked which is resting loosely in the streambed. These are generally a problem to dredge, since the side walls of the hole will continually slide in.
LOW-GRADE: A term applied to ores relatively poor in the metal they are mined for, lean ore.
LOW/BACK PRESSURE AREA: A "back pressure area" may be found at times located in a small size low-pressure area. "Low and back pressure areas" are often found together and formed in the same manner; because of some major change off to one side of the waterway, change in the bedrock floor, or where the waterway changes direction.
LOW PRESSURE AREA: A "low pressure area" is a general term, referring to a place where water slows down or even stops, in comparison to the main flow of water. Low-pressure areas can be of any size and are classified into three categories to clarify a particular size; large, medium, and small.
MAGNETITE: Magnetic iron ore (Fe3O4, 75% iron), having a blackish-red to very dark red color. Magnetite is slightly darker in color than hematite. In water or when wet they look black in color; see "black sands."
MAJOR FLOOD: A flood of an exceptional magnitude, that is not usually seen for many long years; approximately every 30 to 50 years or longer.
MAJOR LOW/BACK PRESSURE AREAS: A low and/or back pressure area of any size, with a very strong force of action.
MAJOR STORM: A rainfall of an exceptional magnitude. See "major flood."
MARCASITE: A mineral often mistaken for "fools gold," though not very often. This mineral is very similar to chalcopyrite in its characteristics; it tarnishes easily, going from bronze or brassy yellow to yellowish or grayish brown. It has a dark streak, and are lighter in weight and harder than gold. Neither of these minerals commonly occur in crystalline form and most often are found as irregularly shaped masses.
MATRIX: The surrounding substance within which something else originates, develops or is contained.
MAXIMUM DEPTH ALLOWANCE: The amount of depth one should agree upon or determine, that would effectively dredge a sample hole; taking into consideration the capabilities of the dredge to be used, personal experience and preference.
MEANDER: One of a series, of somewhat regular and loop-like bends in the course of a stream, developed when the stream is flowing at grade-level through lateral shifting of its course toward the convex side of the original curves.
MEDIUM HIGH PRESSURE AREA: A "high pressure area" the general size of an entire section of streambed; roughly one mile in length. Also called "minor high pressure areas." See "high pressure area."
MEDIUM LOW PRESSURE AREA: A "low pressure area" the general size of an entire section of streambed; roughly one mile in length. See "low pressure area."
MERCURY GOLD: See "amalgamated gold."
MESH SIZE: The number of openings within a 1 inch square of screen in which materials are sifted. The most common sizes for screens used with concentrates in mining are: #20, #30, #40, #60, #80, and #100 mesh size.
MICRO-FINE GOLD: A loose description of very fine size particles of gold. This gold is so fine, that it takes thousands of pieces to make a grain; 480 grains = 1 troy ounce; and can run as small as 1,000 flakes or colors a milligram; 31,103 milligrams = 1 troy ounce. Also called "ultra-fine" gold.
MILLING ORE: Rock formations containing particles of gold, that is in chemical combination with other minerals. These must be broken up and chemically processed to free the gold.
MINE DUMPS: Discarded low-grade ore or waste materials that are found accumulated into piles, next to or downhill from tunnel or shaft openings etc.; mine tailings. Also called "waste debris."
MINER LOW/BACK PRESSURE AREAS: A low and/or back pressure area of any size, with a very weak force of action.
MINIMUM DAILY ACCEPTABLE ALLOWANCE: The amount of gold recovery; pay; needed per day that would not only pay for expenses incurred but be an acceptable profit for those mining it out.
MINING SEASON: 1. The length of time a particular area of government owned land is open to mining. 2. A "mining season" can also be interpreted loosely as; the time generally allowed by an areas particular seasonal changes or weather conditions that allows one to mine.
MOTHER LODE: 1. The source or main vein. 2. The name of California's largest gold producing area, derived from its source or main vein of which the gold comes from. It is in an area, which begins east of Sacramento, on the western slope of the Sierra Nevada mountains and covers some 100 square miles.
NATIVE GOLD: Typical metallic gold found naturally through a mining region or a particular strata.
NATURAL BED: See "natural streambed formation."
NATURAL STREAMBED FORMATION: A section of streambed that is fully reformed or reverted to its natural state; the majority of the larger cobbles and rock are found to be placed, to the least resistance to the flow. Also called a "naturally formed streambed" or "natural bed" for short.
NATURALLY FORMED STREAMBED: See "natural streambed formation."
NEW GOLD: Gold of any size, found in a recently reformed streambed after a major flood; a flood of a magnitude to reform the streambed materials into "naturally formed streambed." Anything less would be flood gold."
NUGGET GOLD: A water-worn piece of native gold. The term is restricted to pieces of some size, not mere particles. Anything larger than, one pennyweight for example, may be considered a nugget. Fragments and lumps of vein gold are not called "nuggets," because the idea of alluvial origin is implicit.
OLD BEDS: This is a loose term used by dredgers, referring to those more recent "ancient streambeds," still inside the waterway or still within reach of modern dredging equipment.
OLD GOLD: Gold of any size, found in an old streambed; ancient, Tertiary, or otherwise; or parts thereof that have washed into the waterway, or gold found contained within hardpan would be considered "old gold."
OUTCROPPING: Portions of bedrock protruding through the soil or gravels along the shoreline of a waterway. Those of interest to the dredger will be found to extent out into the waterway.
OUTLET: The point where a channel is cut off and exposed by a ravine or canyon on the downstream end. Usually applied to buried Tertiary channels.
OVERBURDEN: Worthless or low-grade surface material covering a body of useful mineral. Gravel, rock, clay, sand, etc. that covers the bottom of a river or stream down to the bedrock. The term "overburden" is also used as a measurement of depth; example, if the water depth is 6 feet to the bottom, and the overburden is 10 more feet to the bedrock, you would have 16 feet to bedrock, with a 10 foot overburden to work.
PAY DIRT: Any type of ground, earth, gravels, sand, etc. that is profitable to mine. This depends on the miner's own viewpoint as to what is profitable. It may also be called "pay-lead," or "lead."
PAY LEAD: See "pay dirt."
PAYSTREAK: A limited horizon within a streambed placer, containing a concentration of valuables or made up of material rich enough to mine. Pay streaks in gold placers, are commonly found in well-defined areas on, or near bedrock; also called "stringer" or "stringer deposit." They are commonly narrow, sinuous, and discontinuous.
PAY VALUE: The worth or value placed on materials to be mined; amount of expected gold recovery from a given amount of materials.
PERMANENT DEPOSIT: In placer mining, this refers to gold deposited on the bedrock floor; especially those caught within the bedrock itself. It would take a major flood of equal or greater magnitude to release this kind of deposit. See "retention."
PIPE CLAY: A term used for clays, or clay like materials found in finely laminated beds, within Tertiary channels. Some may consist of volcanic material that has fallen into the water in the form of ash and taken on a stratified form resembling clay in appearance.
PITCH: Used in connection with bedrock in the channel or rim to express descent.
PLACER GEOLOGY: The study of all types of placers; alluvial & eluvial; how they were formed and how they interact or work together.
PLACER: A place where gold is obtained by the washing of materials: rocks, boulders, sand, clay, etc. containing gold or other valuable minerals by the elements. These are deposits of valuable minerals, in our case, native gold, are found in the form of dust, flakes, grains, and nuggets. In the United States mining law, mineral deposits, not veins in place, are treated as placers as far as locating, holding, and patenting are concerned. The term "placer" applies to ancient (Tertiary) gravel as well as to recent deposits, and to underground (drift mines) as well as surface deposits.
PLACER MINING: The obtaining of values; minerals; from placers by washing or dredging.
PLACER DEPOSIT: A mass of gravel, sand, or similar material resulting from the crumbling and erosion of solid rocks, which contains valuable minerals; gold, silver, platinum, tin, ect.; that have been derived from the rocks or vein.
PLANATION: Lateral mechanical erosion, as of a valley, by a running stream.
PLAYED-OUT: This is when a deposit of gold being mined becomes less than the minimum acceptable allowance in recovery or is fully recovered and mined out. Also called "play out."
POCKET GOLD: Native gold found in concentration in the remnants of ore veins, or sometimes seen as bulging sections of "spill" from these veins or quartz veins containing veins and/or pockets of free-gold. These are characterized by sharp, jagged rough surfaces in many unusual and distinctive nforms and shapes. It is usually distinguished by its roughness, since it hasn't traveled any distance from its original location.
POINT BARS: See "skim bar."
POPCORN GOLD: A loose description of small pieces of gold, resembling popcorn in shape and size.
PRESSURE EDDY: An eddy with a circular motion, formed when the streams current pushes against a natural or artificial obstruction.
PROSPECTING: 1. In most cases, prospecting simply is the searching for new deposits. 2. Work merely intended to discover a pay lead in a drift mine, or to locate a channel. 3. Drilling a known placer; including that of an active waterway; deposit to determine its value or delineate a mineable area; placer drilling.
PROSPECTOR: One who prospects likely areas for signs of gold, prior to starting a production mining operation; also called a "sniper." Samples are taken at likely sites; usually by digging or dredging sample holes; or at random to locate payable ground. Sampling is continued until a deposit is either suspected or found acceptable to those that will be working the deposit out.
PUMPKIN SEED GOLD: A loose description of small pieces of gold resembling a pumpkin seeds basic shape and size; smooth, thick, and flat.
PUNCHING A HOLE: To dredge a sample hole through streambed materials down to bedrock or to your maximum depth allowance to determine how rich the site is.
PYRITE: The most common mineral mistaken for gold; "fools gold." It occurs as veins or as scattered grains in many types of rocks. Seen in exposed surfaces in a rock, or as grains in a stream, it is often brown in color on the outside. This is the result of the exposed parts having been oxidized to limonite, a more stable iron mineral. The crystal faces are often striated parallel to the edges of the face. Pyrite can be distinguished from gold by its greater hardness, its lower specific gravity; weight; its dark streak, and by the striations on crystal faces, when it is present.
PYRRHOTITE: A mineral often mistaken for "fools gold," though not very often. Very similar to that of Chalcopy-rite and Marcasite except that pyrrhotite, when pure, is magnetic and can be picked out of mixed gravel with a strong magnet; the same as magnetic black sand. Pyrrhotite has the same dark streak and and tarnishes easily, going from bronze or brassy yellow to yellowish or grayish brown. It is harder and more light weight than gold. Pyrrhotite does not occur in crystalline form and is most often found as irregularly shaped masses.
Copyright 1992© Modern Gold Dredging / Published by Heavy Metal Mining Company, Springfield, Missouri, USA.
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