For guidance purposes only. Not comprehensive or legal advice.
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A property located next to or near an existing mining operation or mineral claim. Adjacent property status is significant in resource estimation because geological continuity from a producing mine to an adjacent claim can support more confident resource classification. Under NI 43-101, historical estimates from adjacent properties must be disclosed with appropriate caveats about data verification. 5
Aerial Tramway
A system for transporting ore or rock in buckets suspended from a cable – used in mountainous terrain where roads are impractical. Historic aerial tramways were essential to accessing high-elevation mines in Colorado, British Columbia, and the Andes. Modern equivalents use enclosed gondola systems. 1
Alluvial Deposit (Placer)
Sand, gravel, or other material removed from a parent rock by water, time, and erosion, and deposited at a distant location. Alluvial deposits concentrate heavy minerals – including gold, platinum, cassiterite (tin), and diamonds – through gravity settling during transport. The concentration process that creates placer deposits is nature’s own gravity separation. See also: Placer Mining. 2
Anticline
An upward fold or arch in rock strata – the rock layers bend upward like an inverted U. Anticlines are important structural traps in both petroleum geology and hard rock mining, as they can concentrate hydrocarbons (in oil and gas) or create conduits for hydrothermal mineralization. The limbs of an anticline often host fault-related mineralization. 5
Appraisal Well / Appraisal Drilling
See Oil & Gas. In mining contexts, the equivalent is a systematic drill program following an initial discovery to define the extent and grade of a mineralized zone. 5
Assessment Work
Work that is required by law to maintain legal control of mining claims. Government standards require companies to spend a certain amount annually on qualified activities – mapping, sampling, testing, trenching, drilling, etc. – or pay cash in lieu. Assessment work keeps a claim in good standing and demonstrates serious intent to develop the property. Failure to perform or record assessment work on time results in forfeiture of the claim. 1,2
Attitude
The direction and degree of dip of a geological structure – a vein, lode, or zone of mineralization. Attitude is described by two measurements: strike (the compass direction of the horizontal line on the plane of the structure) and dip (the angle and direction of inclination below horizontal). Understanding attitude is essential for planning underground mine development and targeting drill holes. 2
Auriferous
Gold-bearing material – rock, gravel, or soil containing gold. From the Latin aurum (gold). An auriferous vein or formation is the primary target of gold exploration drilling. The concentration of gold in auriferous rock is typically measured in grams per tonne (g/t) or ounces per tonne (oz/t). 2
Basalt
A fine-grained, dark-colored igneous rock – solidified ancient lava flows. Basalt is generally not a primary host for precious metal mineralization but is often associated with volcanic-hosted massive sulfide (VHMS) deposits and certain platinum group element (PGE) deposits. 2
Base Metal
A metal inferior in value to gold and silver, generally applied to commercially important metals such as copper, lead, zinc, nickel, cobalt, and aluminum. Base metal mining generates the bulk of global mining revenue by volume – copper alone represents the largest mining commodity market by value after iron ore. Base metal prices are highly cyclical, driven by global industrial production, particularly Chinese infrastructure and manufacturing activity. 1
Bedrock
The solid rock forming the earth’s crust, frequently covered by overburden (soil, gravel, clay) or water. In placer mining, bedrock is the pay horizon – gold and heavy minerals settle on or in cracks in bedrock because they cannot be carried further by water flow. Identifying bedrock depth is one of the first steps in evaluating a placer deposit. 1,2
Borehole
The hole made by drilling a core drill, rotary drill, or other drilling method. In mining exploration, boreholes provide the core samples used to estimate grade and continuity of mineralization. See also: Diamond Drill. 2
Brownfield
An existing or previously mined area – a project located on or adjacent to ground with prior mining or exploration history. Brownfield projects carry lower geological risk than greenfield projects because historical data (drill holes, production records, metallurgical test results) provides a baseline for resource estimation. Brownfield exploration near producing mines is the preferred discovery strategy of most major mining companies. 2
Cut-Off Grade
The lowest grade of ore that can be mined profitably at a given commodity price, mining cost, and processing recovery. Below the cut-off grade, rock is classified as waste; above it, as ore. Cut-off grade calculations are central to mine planning – as commodity prices rise, lower-grade material becomes ore; as prices fall, the ore body effectively shrinks. Cut-off grade is the primary variable used to convert mineral resources into mineral reserves. 5
Deposit
An area containing a quantity of ore or other mineral material deemed to be mineable at current economic conditions and with current technology. A deposit is distinguished from a mineral occurrence (which may have grade but insufficient size or continuity) and a mineral resource (which has been estimated with geological confidence but not necessarily economic viability). 5
Diamond Drill / Diamond Drilling
A rotary drilling method in which the cutting is done by abrasion using a bit set with industrial diamonds (or synthetic diamond substitutes) attached to the end of long hollow drill rods. Diamond drilling cuts a cylindrical core of rock that is recovered in sections (typically 1.5–6 meters long) and placed in core trays for geological logging and sampling.
Diamond drilling is the gold standard of mineral exploration because it provides:
Continuous rock samples (core) from surface to target depth
Direct visual evidence of rock type, structure, and mineralization
Sample material for assay, metallurgical testing, and geostatistical resource estimation
Oriented core (with gyroscopic tools) for structural geological interpretation
Core diameters range from BQ (36.4mm) to HQ (63.5mm) to NQ (47.6mm) – larger diameter cores provide more representative samples for grade estimation but cost more to drill. 1,2
Dip Needle
A compass whose needle is mounted to swing in a vertical plane, used to detect the magnetic attraction of rocks. Dip needle surveys were an early geophysical prospecting tool for locating magnetic mineral deposits. Modern equivalents include ground magnetometer surveys and airborne magnetic surveys, which can identify magnetic anomalies from aircraft over large areas at low cost. 1
Eluvial
Material that has been weathered and moved from its source by gravity and in-situ decomposition (as opposed to alluvial, which is transported by water). Most placer mines are technically eluvial or colluvial – the gold has moved downslope from its bedrock source but not far. Eluvial deposits are typically found on hillsides above stream valleys and can be rich where erosion has concentrated heavy minerals. 2
Exploration
The prospecting, geophysical surveying, geochemical sampling, diamond drilling, and other work involved in searching for and delineating an ore body. Exploration is the highest-risk phase of mining investment – most exploration targets are not economic. Success rates from first-pass drill testing to economic discovery are typically 1 in 1,000 or lower for grassroots targets. 1
Fault Zone
A zone of rock deformation where movement has occurred along a fracture or series of fractures. Rather than a single clean break, fault zones typically consist of numerous interlacing small faults, crushed rock (breccia), clay gouge, or mylonite. Fault zones are critical in mining geology because they can:
Act as conduits for hydrothermal fluids that deposit gold, silver, and base metals
Serve as ore controls that localize mineralization at structural intersections
Create geotechnical hazards that complicate underground mining
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Fissure
An extensive crack, break, or fracture in rocks. Fissures are important in mining because they provide pathways for hydrothermal fluids that precipitate metal-bearing minerals. Fissure veins – mineralized fractures filled with quartz and metallic sulfides – are the primary ore type in many historical gold and silver mining districts. 1
Footwall / Hanging Wall
The two sides of a vein or ore structure:
Footwall. The wall or rock on the underside (below) of a vein or ore structure – the rock you stand on if you were inside the vein. The footwall is typically more competent and is used as the walking surface in underground stope development.
Hanging Wall. The wall or rock on the upper or top side of a vein or ore deposit – the rock hanging above you if you were inside the vein. The hanging wall is often the more geotechnically challenging side to support.
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Gangue
The worthless minerals associated with valuable minerals in an ore deposit – the waste rock that must be separated from the valuable minerals during processing. Common gangue minerals include quartz, calcite, dolomite, feldspar, and pyrite (when not itself valuable). Minimizing gangue dilution in mining and maximizing gangue rejection in processing are the two key efficiency drivers in mine economics. 1
Geochemical Survey
The study and sampling of the chemical composition of rocks, soil, stream sediment, and other materials to identify anomalous concentrations of metals that may indicate buried mineralization. Geochemical surveys are a standard first-pass exploration tool – soil sampling grids over several square kilometers can identify target areas for more expensive follow-up methods (geophysics, trenching, drilling) at low cost. 2
Geiger Counter
An instrument used to detect radioactive minerals – particularly uranium – by measuring the intensity of ionizing radiation using a Geiger-Müller tube. The instrument registers radiation frequency visually (dial, flashing light) or audibly (earphones). Geiger counters are essential prospecting tools in uranium exploration. Modern scintillometers and handheld spectrometers have largely replaced simple Geiger counters for uranium exploration, providing more quantitative measurements. 1,2
Geological Survey
Surface mapping and sampling of rock outcroppings for the purpose of understanding the geology of an area and identifying targets for exploratory drilling. A geological survey is typically the first technical work conducted on a new property and provides the framework for all subsequent exploration. 2
Grab Sample
A sample of rock or material collected at random (or selectively from the highest-grade material visible) for analysis. Grab samples are the least representative sampling method – they may severely over- or under-represent the true grade of a deposit depending on how samples were selected. Grab sample results must be interpreted with caution and should not be used to estimate mineral resources. 2
Greenfield
A new mining area with no prior exploration or mining history – an entirely unexplored region or geological terrain. Greenfield exploration carries the highest geological risk but also the potential for discovery of entirely new mining districts. Greenfield discoveries have become increasingly rare as accessible terrain has been systematically explored. 2
Grubstake
Finances or supplies (food, equipment) furnished to a prospector in exchange for a share of any mineral discoveries made. The grubstake is one of the oldest financing arrangements in mining – a form of venture capital predating formal securities markets. Modern equivalents include option agreements, where a company earns into a property by spending exploration dollars, and joint venture earn-ins. 1
Historical Estimate
A mineral resource or reserve estimate prepared prior to current NI 43-101 or JORC standards, using historical data that has not been verified by a current Qualified Person. NI 43-101 requires strict disclosure language when referencing historical estimates – they cannot be called current resources or reserves without re-verification. Historical estimates can be valuable indicators of project potential but require independent verification before being relied upon for investment decisions. 4
Host Rock
The rock containing an ore deposit. The host rock type is a key geological indicator – certain deposit types are consistently found in specific host rocks. For example: epithermal gold veins in volcanic rocks, porphyry copper-gold in intrusive rocks, nickel sulfides in mafic/ultramafic intrusions, and iron ore in banded iron formations (BIFs). Identifying the correct host rock is foundational to exploration targeting. 1
Hydraulic Mining
A mining method that uses high-pressure water jets to erode and move large volumes of gold-bearing gravel and overburden. Water is diverted into ditches and wooden flumes at high elevation, channeled through heavy iron pipes, and discharged through a nozzle (monitor or “giant”) at tremendous force – up to 5,000 pounds of pressure. The slurry is then directed through sluice boxes to recover gold. Hydraulic mining was responsible for moving more material in the California Gold Rush than any other method, and also caused catastrophic environmental damage (downstream siltation, landslides). It is now strictly regulated or banned in most jurisdictions. 2
In Situ
In a natural or original position – material that has not been moved, disturbed, or processed. An “in situ” resource estimate describes the metal content of the deposit as it exists in the ground, before mining or processing losses are applied. In situ grade and tonnage are the starting point for all reserve and resource calculations. 5
Induced Polarisation (IP)
A geophysical prospecting method that passes an electrical current through the ground and measures the chargeability and resistivity of subsurface rocks and minerals. IP surveys are particularly effective at detecting disseminated sulfide mineralization – the typical host for porphyry copper, bulk-tonnage gold, and base metal deposits – which creates a distinctive IP anomaly (chargeability high). IP is one of the most widely used geophysical methods in mining exploration. 5
Industrial Minerals
Non-metallic minerals with commercial value for their physical or chemical properties rather than metal content. Examples include: silica sand (glass, semiconductors), limestone (cement, lime), potash (fertilizer), salt, gypsum, talc, kaolin, and gravel. Industrial mineral operations tend to be lower-value per tonne but much higher volume than precious or base metal mines, and are typically located close to their end markets to minimize transportation costs. 5
Junior Mining Company
A small exploration-stage or development-stage mining company, typically listed on a junior exchange (TSX Venture, ASX, AIM) with limited or no production and a market capitalization generally under $200M. Junior miners are the primary discovery engine of the global mining industry – the vast majority of significant mineral discoveries are made by junior companies, which are then acquired by mid-tier or major producers. Junior miners offer high risk/high reward investment characteristics and require investors with specific technical and geological evaluation skills. 1
Mother Lode
The primary bedrock source of gold that has been weathered and eroded to create downstream placer deposits. In river placer mining, the size of gold found in the river decreases with distance from the mother lode – larger nuggets indicate proximity to the source. The term also refers to the historic gold-bearing district in the Sierra Nevada foothills of Central California (Amador, Calaveras, El Dorado, and Tuolumne Counties), which was the center of the 1849 California Gold Rush. 2
National Instrument 43-101 (NI 43-101)
A rule developed by the Canadian Securities Administrators (CSA) governing how issuers disclose scientific and technical information about mineral projects to the public. NI 43-101 is the primary standard for mineral project disclosure for companies listed on Canadian exchanges (TSX, TSX Venture). Key requirements:
All public disclosure must be based on advice by a “Qualified Person” (QP) – an engineer or geoscientist with at least five years of experience in the relevant commodity and type of deposit
Mineral resource and reserve estimates require an independent Technical Report by a QP
Historical estimates and non-NI 43-101 compliant resources must be disclosed with specific cautionary language
The standard covers written documents, oral statements, and websites
Covers both exploration-stage and producing mining companies
NI 43-101 is considered more rigorous than SEC Industry Guide 7 (the US standard) and similar in rigor to the JORC Code (Australia) and SAMREC Code (South Africa). 4
Nugget
A water-worn piece of native precious metal – typically gold or platinum – of significant size. Nuggets form when gold is liberated from its host rock by weathering and erosion and then rounded by stream transport. The largest gold nugget ever found – the Welcome Stranger (1869, Victoria, Australia) – weighed 97.14 kg (2,316 troy oz). Nuggets command a premium over bullion value for collector and jewellery markets. 1
Ore
Rock containing valuable minerals in sufficient quantity and grade to be extracted and processed profitably at current commodity prices and with available technology. The distinction between ore and waste is economic, not purely geological – the same rock may be ore at $2,000/oz gold and waste at $1,200/oz. Ore grade is typically expressed in grams per tonne (g/t) for precious metals and percent (%) for base metals. 5
Overburden
Material such as soil, clay, sand, and unconsolidated gravel covering the bedrock or ore body that must be removed before mining can begin. In open pit mines, the overburden strip ratio – tonnes of waste removed per tonne of ore extracted – is a primary determinant of mining cost and economic viability. High strip ratios make deposits uneconomic even at high grades. 2
Payzone / Paydirt
The material containing enough valuable mineral to warrant mining:
Payzone (hard rock) – the mineralized interval in a drill hole or underground working that meets cut-off grade
Paydirt (placer) – the gravel or alluvial material that contains sufficient gold to be economically sluiced. “Striking paydirt” has entered the English language as a metaphor for hitting upon something valuable.
2
Prospect
A mining property whose value has not yet been proved by exploration. A prospect is an early-stage target that has been identified through geological, geochemical, or geophysical work but has not yet been drill-tested. In colloquial usage, “to prospect” means to search for gold or other minerals by surface methods (panning, sampling, visual inspection). 1
Pyrite / Pyrites
A hard, heavy, shiny, pale yellow mineral – iron disulfide (FeS⊂2;) – commonly called “fool’s gold” because its appearance deceived novice prospectors. While pyrite itself is not economically valuable as a metal, it is one of the most important indicator minerals in gold exploration:
Refractory gold deposits (Carlin-type, some epithermal deposits) lock gold within pyrite crystal lattices at sub-microscopic scale – the gold is invisible but real
Pyrite is often spatially associated with gold in hydrothermal systems, making it a useful pathfinder
Arsenopyrite (FeAsS) is an even better gold indicator than pyrite in many deposit types
1,2
Recovery
The percentage of valuable metal in the ore that is successfully extracted by metallurgical treatment. Recovery is a critical economic variable – a deposit with 90% recovery is significantly more valuable than one with 70% recovery at the same grade. Recovery depends on ore mineralogy, particle size distribution, processing method, and circuit design. Metallurgical test work (bench-scale, pilot plant) to establish expected recovery is a prerequisite for feasibility studies and project financing. 1
Rotary Drilling
A drilling method where a drill pipe and bit are rotated while cuttings are returned to surface by circulating air or fluid. Rotary drilling is faster and cheaper than diamond drilling but does not produce core – only drill cuttings that provide less detailed geological information. Used for large-diameter blast holes in open pit mines and for reverse circulation (RC) drilling in exploration, where pressurized air returns chips through the centre of the drill rods. 2
Royalties (NSR)
Money owed to the claim holder, mineral rights owner, or royalty holder as a percentage of production revenue or metal value. Types:
NSR (Net Smelter Return / Royalty). A percentage of the revenue received from sale of ore or concentrate at the smelter, net of transportation and smelting charges. The most common royalty structure in hard rock mining – typically 1–3% for vendor royalties, up to 5% for government or indigenous royalties
NPI (Net Profit Interest). A percentage of net profits after deducting operating and capital costs – only pays when the mine is profitable
Gross Revenue Royalty (GRR). A percentage of total revenue before any deductions – most favorable to royalty holder, most burdensome to operator
Streaming Agreement. A royalty company provides upfront capital in exchange for the right to purchase a percentage of metal production at a fixed low price in perpetuity – popularized by Franco-Nevada, Royal Gold, and Wheaton Precious Metals
Royalties and streaming agreements are attractive investment instruments – they provide commodity exposure without operational risk, and their value compounds as commodity prices rise. 2,5
Sample
A small portion of rock, soil, or mineral material taken for analysis to determine the possible content of valuable elements. Sampling is the most critical and most commonly flawed process in mineral exploration – sample quality (representativeness, contamination prevention, chain of custody) determines the reliability of all subsequent resource estimates. Industry best practice requires:
Duplicate samples for precision assessment
Blanks (barren material) to detect contamination
Certified reference materials (standards) for accuracy control
Independent check assays at a second laboratory
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Ten Bagger
A mining stock that has increased tenfold in value from its purchase price – a return of 1,000%. The term was popularized by investor Peter Lynch. In junior mining, ten-bagger returns are possible (and occasionally achieved) through discovery of a significant new deposit, but they are accompanied by equivalent downside risk. Most junior mining exploration programs fail to find economic mineralization. 5
Ultrabasic / Ultramafic
Igneous rocks composed primarily of iron and magnesium minerals with very low silica content (less than 45%). Ultramafic rocks are the primary host for:
Rotary drilling using compressed air instead of drilling fluid (mud) to remove cuttings from the hole. Air drilling is used in dry, stable formations where water-based drilling fluids would damage the formation or where water is unavailable. Reverse Circulation (RC) drilling – the most common exploration air drilling method – uses high-pressure air to return cuttings through the centre of dual-wall drill rods, producing chip samples. 5
Backstope
The initial lift or slice when commencing to stope or mine from a drift – the first cut taken upward from a development opening. The backstope defines the uppermost working face of a stope and establishes the mining geometry for subsequent slices. 1
Ball Mill
A cylindrical steel container filled with steel balls, rotated to grind ore into fine particles for subsequent processing. Crushed ore is fed into the rotating mill; the cascading steel balls fracture and grind the ore through impact and abrasion. Ball mills are the most common grinding device in mineral processing plants, typically reducing ore from 10–20mm to 75–150 microns (0.075–0.15mm) – fine enough for efficient mineral liberation and recovery. 1
Blast Hole
A hole drilled specifically for blasting purposes – to place explosives that break rock for mining. Blast holes are distinguished from exploration holes (which are for geological information) by their purpose, diameter, and depth. In open pit mines, blast holes are typically 150–350mm in diameter and 6–15m deep, drilled in patterns designed to fragment rock into manageable sizes for loading and hauling. 1
Block Caving
A low-cost underground mining method for large, low-grade, vertically extensive ore bodies. A large block of ore is undercut by drilling and blasting a horizontal tunnel beneath it; the ore above collapses under its own weight, breaking into pieces that are drawn off through extraction tunnels (drawpoints) below. Block caving is the lowest-cost underground mining method per tonne but requires massive capital investment in infrastructure and is only suitable for ore bodies of sufficient size, grade, and rock mass properties.
Modern block cave mines include Palabora (South Africa), El Teniente (Chile), and Resolution (Arizona – proposed). 1,5
Breast
A working face, usually restricted to a stope – the vertical or near-vertical rock face being mined. Drilling and blasting of the breast advances the stope toward the ore body. 1
Change House / Dry House
A building at a mine where workers change into and out of their working clothes, and where wet gear is dried. Modern mine dry houses also include wash facilities, lockers, and safety equipment storage. The change house is the transition point between the surface world and the underground work environment. 1
Collar
The timbering, concrete, or steel casing around the mouth of a shaft or drill hole – prevents the surface soils from collapsing into the opening
The top of a drill hole – the point where the drill string enters the ground. Drill hole collar coordinates (easting, northing, elevation, azimuth, dip) are the primary spatial reference for all downhole data
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Core Barrel
The component of a diamond drill string that collects and retains the core sample as the drill bit advances. The core barrel sits behind the drill bit and fills with a continuous cylindrical core of rock as drilling progresses. When the barrel is full (typically after 1.5–3m of drilling), it is retrieved to surface (by wireline or by pulling the entire rod string) and the core is emptied into labeled core trays. 1
Crosscut
A horizontal underground opening driven across the course of a vein or formation – perpendicular to the ore body – as opposed to a drift which follows along the ore body. Crosscuts provide access from a shaft to an ore structure and allow sampling across the full width of a mineralized zone. 1
Development
Underground work carried out for the purpose of reaching and opening up a mineral deposit. Development includes:
Shaft sinking (vertical access)
Decline construction (ramp access for rubber-tired equipment)
Cross-cutting (horizontal openings across the ore body)
Drifting (horizontal openings along the ore body)
Raising (vertical or near-vertical openings upward)
Ore pass and waste pass construction
Development capital (capex) is typically the largest single cost category in bringing an underground mine into production. 1
Dilution
Waste or low-grade rock that is unavoidably removed along with ore in the mining process, reducing the average grade of material delivered to the mill below the in-situ ore grade. Dilution is expressed as a percentage – 15% dilution means 15% of the material mined is waste. Minimizing dilution is a primary objective of underground mine design – techniques include tight drilling and blasting patterns, paste fill in worked-out stopes, and selective mining methods. 1
Drift (Drive)
A horizontal underground passage that follows along the length of a vein or rock formation (as opposed to a crosscut, which crosses it). Hard rock mines use drifts along ore zones to provide access for drilling, blasting, and ore extraction. A drift is typically 3–5m wide and 3–4m high – large enough for mining equipment but minimizing excavation in waste rock. 1,2
Drifter
A rock drill used for boring horizontal holes for blasting in underground mining. Modern drifters are hydraulic rock drills mounted on automated drill jumbos (drill rigs) – the operator programs the blast hole pattern and the jumbo drills multiple holes simultaneously. 1
Grizzly
A grating (usually constructed of steel rails or bars) placed over the top of a chute, ore pass, or loading pocket to stop oversized pieces of rock or ore. Material that passes through the grizzly falls to the level below; oversize is broken up by secondary blasting or mechanical breakers before passing through. 1
Grouting
The process of sealing off water flow in rocks by forcing thin cement slurry or chemical grout into cracks and fissures, usually through diamond drill holes. Grouting is used in underground mining to stabilize water-bearing ground, strengthen fractured rock masses, and prevent groundwater inflow that would otherwise require expensive pumping. 1
Hard Rock Mine
A mine that extracts ore from solid bedrock, as opposed to placer or alluvial operations that process loose sediments. Hard rock mines are either underground (accessed by shafts and declines) or open pit (excavated from the surface downward). Hard rock mining is used for the majority of global metal production including gold, copper, zinc, nickel, and iron ore. 2
Highgrade / Highgraded
Highgrade – rich ore; the selective mining of the best (highest-grade) ore in a deposit, sometimes to the detriment of the overall resource by removing the premium ore and leaving behind lower-grade material that is then uneconomic to mine
Highgraded – colloquially, one who steals rich ore, especially gold, from a mine. Ore theft (highgrading) is a persistent security challenge in precious metal mines
1
Launder
A chute or trough used to convey pulp (slurry), water, or powdered ore in the milling process. Launders use gravity flow to transport material between processing stages without pumping. 1
Mill Heads
The average grade of ore fed into a processing mill. Mill head grade is a key performance metric in mine operations – it reflects both the in-situ ore grade and the dilution introduced by the mining process. Actual mill head grade is typically lower than the estimated resource grade due to dilution and ore loss in mining. 1
Monitor (Giant)
An apparatus fitted with a nozzle used to direct water under high pressure in hydraulic mining operations. Also known as a “giant.” The monitor was the primary tool of California Gold Rush hydraulic mining – operators could direct the water jet to erode entire hillsides, processing the resulting slurry through downstream sluice boxes. 1
Open Pit Mine
A mine excavated from the surface downward in a series of benches – essentially a large hole that increases in diameter as it deepens. Open pit mining is used for large, low-grade ore bodies where the cost of underground development would not be justified. Key economic parameters:
Strip ratio. Tonnes of waste removed per tonne of ore – typically 1:1 to 4:1 for economic open pits; some very large pits (Bingham Canyon, Escondida) operate at higher ratios due to exceptional grades
Pit slope angle. The overall angle of the pit walls – steeper slopes mean less waste removal but higher geotechnical risk
Pit shell. The optimized 3D boundary of the economic pit at a given commodity price and cost assumption
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Portal
The surface entrance to a tunnel, adit, or decline. The portal is the point where underground workings meet the surface – it is typically supported with concrete or steel arches and reinforced to prevent collapse. Portal location is determined by topography, geology, and proximity to ore. 1
Rockbolting
The act of stabilizing underground roof or wall strata by inserting and tensioning steel bolts into holes drilled into the rock mass. Rock bolts act as reinforcement – they stitch together fractured rock layers and prevent falls of ground. Modern underground mines use rock bolts as the primary ground support method, typically installed immediately after each blast as the heading advances. 1
Rock Burst
The sudden, violent failure of walls or pillars in a mine caused by excessive stress in the surrounding rock mass – accompanied by a violent release of energy, often felt as a seismic event. Rock bursts are a major safety hazard in deep, high-stress mines (South African gold mines at 3,000–4,000m depth are the most burst-prone in the world). Modern mines in burst-prone ground use microseismic monitoring networks, destress blasting, and yielding support systems to manage the risk. 1
Shaft
A vertical or steeply inclined underground opening used for access, hoisting ore and waste, personnel transport, and ventilation. Shafts are the primary infrastructure investment in underground mining – a modern production shaft can cost $50,000–$100,000+ per metre to sink, depending on depth and diameter. Shaft sinking is one of the longest-lead-time activities in mine development. 5
Sidetrack / Sidetracking
In mining drilling, the redirection of a drill hole from its original path to avoid an obstruction or to target a different geological objective from the same collar. See also Oil & Gas Glossary for the equivalent petroleum drilling term. 5
Sluice
A long trough with riffles (raised bars perpendicular to flow) used to separate gold and heavy minerals from lighter material using flowing water. The heavy gold settles behind the riffles; lighter waste material flows over and out. Sluicing is the fundamental placer gold recovery method – from primitive wooden sluice boxes of the Gold Rush era to modern large-scale sluice plants processing thousands of tonnes per hour. See: Placer Mining section. 2
Square Set
A set of timbers used for ground support in underground mining, consisting of cap (horizontal), girt (horizontal brace), and post (vertical). Square set timbering was the dominant underground support method in the 19th and early 20th centuries, particularly in the Comstock Lode silver mines of Nevada. Modern mines have largely replaced timber with steel sets, rock bolts, and shotcrete. 1
Station
An enlargement of a shaft at a level horizon, used primarily for storage and handling of equipment, ore, and personnel. Shaft stations provide the working space for loading skips, parking equipment, and accessing level workings. 1
Stock Pile
Broken ore accumulated in a heap on the surface, pending treatment or shipment. Stockpiles serve as buffers between mining and processing rates, allow ore blending to achieve consistent mill feed grade, and provide flexibility in mine scheduling. Low-grade stockpiles may be held for later processing when economics improve. 1
Stope
The excavation formed by the removal of ore from around a mine development opening – the actual underground space where ore is extracted. Stoping is the productive phase of underground mining (as opposed to development, which creates access). Common stoping methods include:
Open (longhole) stoping. Large open voids with minimal support – efficient for competent rock and wide ore bodies
Cut and fill stoping. Each horizontal slice is mined and the void filled (with waste rock, hydraulic fill, or paste) before the next slice – good for weak rock or high-value narrow veins
Sublevel stoping. Ore blasted from rings drilled from sublevels into an open slot – high productivity for competent ore bodies
Shrinkage stoping. Broken ore retained in the stope as a working platform; ore is drawn off at the bottom as stoping advances upward
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Tailing Pile / Tailings
Material rejected from a mill after recoverable valuable minerals have been extracted – the residue of ore processing. Tailings are typically a fine-grained slurry deposited in engineered tailings storage facilities (TSFs):
Tailings can contain residual metals at sub-economic concentrations, process chemicals (cyanide in gold processing, acid-generating sulfides), and fine particles that disperse easily
TSF failure is one of the most catastrophic risk events in mining – the Brumadinho (Brazil, 2019) and Mount Polley (Canada, 2014) failures caused significant environmental damage and fatalities
Modern tailings management uses filtered (dry stack) tailings, paste tailings, and geotechnical monitoring systems to reduce failure risk
1,2
Trommell
A rotating cylindrical screen used to wash and size placer material. Material is fed into the rotating drum; water sprays wash the fine material through the screen openings; oversize material exits at the far end. Trommel output (fine material + water) is fed directly to the sluice for gold recovery. Trommels are the workhorse of modern placer gold operations. 5
Tunnel
A horizontal underground passage open at both ends. The term is loosely applied in mining to any horizontal opening, but technically an adit is open at only one end, while a tunnel passes completely through a geological feature. Tunnels may be driven for access, ventilation, or drainage, and are not necessarily mining-related. 1
Workover
See Oil & Gas. In mining contexts, the equivalent is a rehabilitation or re-treatment of a previously mined area or processed tailings pile using improved technology or at higher commodity prices. 5
A process by which gold and silver are extracted from ore by dissolving them in mercury – the gold amalgamates (alloys) with mercury, which is then separated and the mercury evaporated to recover the gold. Amalgamation was the dominant gold recovery method in the 19th century but is now largely banned due to mercury toxicity and environmental contamination. Artisanal and small-scale mining (ASM) operations in developing countries continue to use amalgamation illegally – it is one of the largest sources of mercury pollution globally. 2
Autogenous Grinding
The process of grinding ore in a rotating mill using large pieces of the ore itself as the grinding medium, instead of conventional steel balls or rods. Semi-autogenous grinding (SAG) mills use a small charge of steel balls to supplement the ore-on-ore grinding. SAG mills are the standard first-stage grinding device in modern concentrators – a single SAG mill may be 12–14m in diameter and process 60,000+ tonnes per day. 1
Bullion
Precious metal (gold, silver, platinum) in bars, ingots, or other uncoined form. Doré bullion is a semi-pure alloy of gold and silver produced at mine sites and shipped to refineries for further purification. London Good Delivery bars (the standard for international gold trade) must be 99.5%+ purity and weigh approximately 400 troy ounces. 1
Calcite Value / Calorific Value
The amount of heat energy that can be obtained from one pound of coal or oil, measured in BTUs (British Thermal Units). Calorific value is the primary quality parameter for thermal coal – higher BTU coal commands a premium because less coal is needed to generate a given amount of electricity or heat. 5
Cathode
A rectangular plate of refined metal produced by electrolytic refining (electrowinning). In copper mining, cathodes are produced by electrowinning of copper from leach solutions (SX-EW process) – the cathode is the final product, typically 99.99% pure copper. Gold cathodes (sponge) are produced in the Merrill-Crowe process or electrowinning from carbon-in-leach (CIL) circuits. Cathodes are melted into commercial shapes (ingots, rods, billets) for final sale. 1
Clean Metallurgy
A metallurgical process that produces high-purity products with minimal environmental impact – no hazardous reagents, minimal waste, and direct production of saleable product. Clean metallurgy is an aspirational standard in modern mining, particularly for lithium, cobalt, and battery minerals where supply chain transparency and environmental footprint are increasingly scrutinized by end users (electric vehicle manufacturers, battery producers). 3
Concentrate
A product containing the valuable metal and from which most of the waste (gangue) in the ore has been removed by processing. Concentrates are the intermediate product between raw ore and refined metal:
Copper concentrate: typically 25–35% Cu, shipped to smelters
Gold concentrate: high-grade material for further refining
Zinc concentrate: typically 50–55% Zn
Lead concentrate: typically 65–70% Pb
The concentrate is sold to a smelter under a terms and conditions (T&C) agreement specifying payable metals, treatment charges (TC), and refining charges (RC). TC/RC negotiation is a primary revenue lever for mining companies. 1,2
Cyanidation
The dominant method of extracting gold and silver from ore by dissolving them in a dilute (0.01–0.05%) sodium cyanide solution. The cyanide forms a soluble gold-cyanide complex; the gold is then recovered from solution by carbon adsorption (CIL/CIP), zinc precipitation (Merrill-Crowe), or electrowinning. Cyanidation recovers 90–97% of gold from amenable ores.
Cyanide management is the primary environmental challenge of gold processing – accidental spills can cause acute ecological damage. The International Cyanide Management Code (ICMC) provides a voluntary standard for responsible cyanide use. 1
Differential Flotation
A milling process using the flotation method to produce separate concentrates of each valuable mineral in a polymetallic ore (e.g. lead-zinc, copper-molybdenum, copper-gold). Different minerals are selectively floated (or depressed) using specific reagent combinations, allowing each valuable mineral to be recovered in its own high-grade concentrate rather than in a bulk mixed concentrate. Differential flotation maximizes the value of complex polymetallic ores. 1
Extraction
The process of separating valuable minerals or metals from ore or waste materials. Extraction encompasses all physical and chemical separation processes including crushing, grinding, flotation, leaching, cyanidation, smelting, and refining. The overall extraction efficiency (mine to refinery) is the product of mining recovery, processing recovery, and refining recovery. 2
Filter Press
Equipment used to dewater slurries by forcing liquid through filter cloths under pressure, leaving a filter cake of solid material. In gold processing, filter presses are used to dewater concentrates before shipment and to treat cyanide tailings to reduce water content. Filtered tailings (filter cake) can be dry-stacked rather than stored in tailings ponds, significantly reducing TSF failure risk. 1
Fine Gold
Almost pure gold. Fineness is the proportion of pure gold or silver expressed in parts per thousand – 999.9 fine gold is essentially pure gold (99.99%). Gold karat markings are another expression of fineness: 24 karat = 999.9 fine; 18 karat = 750 fine (75% gold); 14 karat = 585 fine. Investment-grade gold bullion is typically 999.5 fine or better. 1
Flotation
A processing method in which valuable mineral particles are induced to attach to air bubbles and float to the surface of a slurry, while gangue minerals sink. Flotation exploits differences in surface chemistry between minerals – reagents (collectors, frothers, modifiers) are added to make valuable minerals hydrophobic (water-repelling) and gangue minerals hydrophilic (water-attracting).
Flotation is the most widely used mineral processing method for base metal sulfides (copper, zinc, lead, nickel) and is used for many gold deposits. A modern flotation circuit may consist of 20–100 flotation cells, each 50–300 cubic meters, operating in rougher, scavenger, and cleaner stages. 1
Flowsheet
A diagram showing the sequence of operations, step by step, by which ore is treated in a milling, concentration, or smelting process. The flowsheet is the central engineering document for a processing plant – it specifies all unit operations (crushing, grinding, classification, flotation, leaching, dewatering, tailings disposal) and their interconnections. Flowsheet development is a primary deliverable of metallurgical test work programs. 1
Free Milling
Ores of gold or silver from which the precious metals can be recovered by simple physical concentration methods (gravity, amalgamation, simple cyanidation) without roasting or complex chemical treatment. Free milling ore is the most desirable ore type because processing costs are lower and recoveries are higher. The opposite is “refractory” ore, where gold is locked in sulfide minerals and cannot be directly cyanided without pre-treatment (roasting, pressure oxidation, or bacterial oxidation). 1
Jaw Crusher
A machine in which rock is broken by the action of one fixed and one moving steel jaw that closes and opens cyclically. Jaw crushers are typically the first crushing stage, reducing run-of-mine ore from boulder sizes (up to 1m+) to 100–200mm for subsequent processing. They are characterized by their simplicity, durability, and ability to handle very hard, abrasive material. 1
Leaching
The chemical extraction of valuable metals from ore using a solvent (leaching solution). Types:
Heap Leaching. Crushed ore is stacked on lined pads; leaching solution (cyanide for gold/silver, sulfuric acid for copper) is applied to the top; pregnant solution collected at the base is processed to recover metal. Low capital cost, low operating cost, but lower recovery than tank leaching
Tank Leaching (CIL/CIP). Finely ground ore is leached in agitated tanks; gold is adsorbed onto activated carbon (Carbon-In-Leach or Carbon-In-Pulp) – higher cost but higher recovery for fine-grained gold
Dump Leaching. Run-of-mine ore or low-grade waste is leached in-situ on unlined pads – lowest cost, lowest recovery
2,5
Metallurgy
The science and engineering of extracting metals from their ores, refining them, and preparing them for use. In mining, “metallurgy” encompasses:
Comminution (crushing and grinding to liberate minerals)
Concentration (flotation, gravity, magnetic separation)
Metallurgical test work (bench tests, locked-cycle tests, pilot plant campaigns) is required at every stage of mine development – from scoping study through bankable feasibility. 3,5
Milling Ore
Ore that contains sufficient valuable mineral to be treated by milling process at current commodity prices and processing costs. Material below mill cut-off grade is classified as waste. 1
Pebble Mill
A grinding mill similar in construction to a ball mill but using hard pebbles (natural or ceramic) as the grinding medium instead of steel balls or rods. Pebble mills are used when iron contamination from steel grinding media would interfere with downstream processing (e.g. some industrial mineral applications). 1
Rod Mill
A rotating cylindrical mill employing steel rods as the grinding medium. Rod mills produce a more uniform product size distribution than ball mills (rods are selective grinders) and are used as the first stage of fine grinding before ball milling. 1
Shaker Screen
A vibrating screen used to classify (size-separate) crushed or ground ore into size fractions. Shaker screens are used throughout mineral processing plants to separate material for different processing paths and to close grinding circuits (oversize returned to the mill for regrinding). 1
Tube Mill
A piece of milling equipment consisting of a revolving cylinder half-filled with steel rods or balls, into which crushed ore mixed with water or other solution (slurry) is fed for fine grinding. Tube mills are a general category encompassing ball mills and rod mills. 1
The following definitions are primarily per the CIM Definition Standards as incorporated into NI 43-101, and internationally consistent with the JORC Code (Australia), SAMREC Code (South Africa), and PERC Code (Europe).
Measured Resource
That part of a mineral resource for which quantity, grade, densities, shape, and physical characteristics are so well established that they can be estimated with confidence sufficient to allow the appropriate application of technical and economic parameters to support production planning and evaluation of economic viability. The estimate is based on detailed and reliable exploration, sampling, and testing information gathered from locations – outcrops, trenches, pits, workings, and drill holes – spaced closely enough to confirm both geological and grade continuity. 4
Indicated Resource
That part of a mineral resource for which quantity, grade, densities, shape, and physical characteristics can be estimated with a level of confidence sufficient to allow the appropriate application of technical and economic parameters to support mine planning and evaluation of economic viability. The estimate is based on detailed and reliable exploration and testing information gathered from locations spaced closely enough for geological and grade continuity to be reasonably assumed. 4
Inferred Resource
That part of a mineral resource for which quantity and grade can be estimated on the basis of geological evidence and limited sampling, with geological and grade continuity reasonably assumed but not verified. Inferred resources carry the most uncertainty – they cannot be converted directly to reserves and should not be included in economic analyses for project financing. Additional drilling is required to upgrade inferred resources to indicated or measured status. 4
Mineral Resource
A concentration or occurrence of natural, solid, inorganic or fossilized organic material in or on the Earth’s crust in such form and quantity and of such grade or quality that it has reasonable prospects for economic extraction. The location, quantity, grade, geological characteristics, and continuity of a mineral resource are known, estimated, or interpreted from specific geological evidence and knowledge.
Mineral resources are subdivided, in order of increasing geological confidence, into Inferred, Indicated, and Measured categories. Resources are not reserves – they have not been demonstrated to be economically mineable and should be treated accordingly by investors. 4
Mineral Reserve
The economically mineable part of a measured or indicated mineral resource demonstrated by at least a preliminary feasibility study (pre-feasibility study). The study must include adequate information on mining, processing, metallurgical, economic, and other relevant factors that demonstrate, at the time of reporting, that economic extraction can be justified. A mineral reserve includes diluting materials and allowances for losses that may occur when the material is mined. Mineral reserves are subdivided into probable and proven. 4
Probable Reserve
The economically mineable part of an indicated, and in some circumstances a measured, mineral resource demonstrated by at least a preliminary feasibility study. Probable reserves carry less certainty than proven reserves but are typically bankable – they can support project debt financing when demonstrated by a rigorous feasibility study. 4
Proven Reserve
The economically mineable part of a measured mineral resource demonstrated by at least a preliminary feasibility study. Proven reserves represent the highest confidence reserve category – sufficient data exists to support detailed mine planning and financial commitment. Most project finance for large mining projects is based on proven and probable (P&P) reserves. 4
Ore Reserve
The amount of ore available for extraction – a broader colloquial term often used interchangeably with “mineral reserve.” In NI 43-101 and JORC compliant disclosures, “mineral reserve” is the technically correct term. 5
Early Stage Exploration Property
A property at the earliest stage of mineral exploration – geological mapping, sampling, and first-pass geophysics have been completed but no drill holes have been completed. Early stage exploration properties offer maximum upside but carry the highest geological risk and require the most capital before economic assessment is possible. 5
Development Property
A mineral property that has a defined mineral resource or reserve and is being advanced toward production, but has not yet commenced commercial mining. Development properties have completed pre-feasibility or feasibility studies and are in the permitting, financing, or construction phase. 5
Producing Issuer
A mining company that has a mine in commercial production – generating revenue from ore sales. Under NI 43-101, producing issuers have different disclosure obligations than exploration-stage companies. 4
Preliminary Assessment (Scoping Study)
An initial economic assessment of a mineral project that provides a first estimate of whether a project may be economically viable. A preliminary assessment uses inferred resources (which cannot be used in reserves) and therefore carries the highest economic uncertainty – it is not a basis for project financing but may support an initial public offering or equity raise for further exploration. 4
Preliminary Feasibility Study (Pre-Feasibility Study / PFS)
A comprehensive study of the viability of a mineral project that has advanced to a stage where the mining method (underground or open pit), pit configuration, and effective processing method have been established. Includes a financial analysis based on reasonable technical, engineering, legal, operating, economic, social, and environmental assumptions sufficient for a Qualified Person to determine if part or all of the mineral resource may be classified as a mineral reserve. A PFS is sufficient to convert indicated resources to probable reserves. Typical accuracy: ±25%. 4
Feasibility Study
A definitive technical and economic study of a mineral project providing the highest level of confidence. A feasibility study forms the basis for a final investment decision (FID) and project debt financing. It includes detailed engineering, site investigations, metallurgical testing, environmental and social impact assessment, and a financial model with sensitivity analysis. Typical accuracy: ±15%. A positive feasibility study is a prerequisite for project finance loans from commercial banks and development finance institutions. 4,5
Technical Report
A document required under NI 43-101 to support disclosure of mineral project information, including resource estimates, reserve estimates, feasibility studies, and material property acquisitions. Technical Reports must be prepared by, or under the supervision of, one or more Qualified Persons independent of the issuer. They are filed on SEDAR (System for Electronic Document Analysis and Retrieval) and are publicly accessible. 4
Qualified Person (QP)
An individual defined in NI 43-101 as an engineer or geoscientist with at least five years of experience in mineral exploration, mine development, production activities, or project assessment in the type of mineral deposit and mining activity relevant to the project. Must be a member in good standing of a recognized professional association. The QP takes professional responsibility for the technical content of NI 43-101 disclosures. 4
Data Verification
The process of confirming that geological data (drill hole assays, collar surveys, downhole surveys, sampling records) used in a mineral resource estimate is accurate, representative, and has been collected and handled using appropriate QA/QC procedures. Data verification by the Qualified Person is a mandatory requirement of NI 43-101 Technical Reports. 4
JORC Code
The Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves – the Australian and New Zealand equivalent of NI 43-101. Administered by the Joint Ore Reserves Committee (JORC) of the Australasian Institute of Mining and Metallurgy (AusIMM), the Australian Institute of Geoscientists (AIG), and the Minerals Council of Australia. The JORC Code is required for companies listed on the ASX (Australian Securities Exchange). 4
SAMREC Code
The South African Code for the Reporting of Exploration Results, Mineral Resources and Mineral Reserves – the South African equivalent of NI 43-101 and JORC. Required for companies listed on the JSE (Johannesburg Stock Exchange) and reporting on South African mineral properties. 4
SEC Industry Guide 7
The US Securities and Exchange Commission’s disclosure standard for mining companies reporting to US investors. Guide 7 historically used a different definition of “reserves” (requiring feasibility-level study and current-price economics) than NI 43-101 or JORC, creating disclosure inconsistencies for companies listed on both US and Canadian exchanges. The SEC has replaced Guide 7 with the new Regulation S-K 1300 (S-K 1300), effective for fiscal years beginning January 1, 2021, which aligns more closely with international standards including NI 43-101 and JORC. 4,5
IMMM Reporting Code / IMVAL
International reporting codes developed by the Institute of Materials, Minerals and Mining (IOM3) for use in jurisdictions where other codes (NI 43-101, JORC, SAMREC) do not apply. Used primarily for projects in African, Asian, and Eastern European jurisdictions. 4
Placer mining recovers heavy minerals – primarily gold – from alluvial or eluvial deposits using water and gravity. The gold’s high density (19.3 g/cm³, vs. 2.6–2.7 for quartz) causes it to settle while lighter material is washed away.
Gold Pan
The most basic placer mining tool – a shallow metal or plastic dish used to wash gravel and concentrate heavy minerals. Gravel and water are swirled in the pan; lighter material washes over the edge while gold and heavy minerals settle to the bottom. Panning is primarily a prospecting tool – it can process only a few kilograms of material per hour, insufficient for commercial production but invaluable for sampling and verifying placer deposits. 2
Sluice Box
The most commonly used commercial placer mining tool – a long, narrow, inclined channel through which water flows, carrying placer material over riffles that trap gold. Sluice boxes range from simple hand-built wooden boxes to large commercial sluices processing hundreds of tonnes per hour. The riffles create turbulence and low-velocity zones where dense gold settles while lighter material is carried through. Modern sluices use expanded metal, Hungarian riffles, or carpet matting to maximize gold retention. 2
Rocker Box (Cradle)
A compact, portable sluice that is rocked like a cradle to agitate material while water is poured over it. The rocker box requires less water than a sluice and is more effective in areas where water is scarce. It was widely used in the California and Australian gold rushes. Still used today in artisanal gold mining and low-water placer operations. 2
Long Tom
A sluice box variant – longer and narrower than a standard sluice, without riffles, used to transport material to a sluicing area rather than for primary recovery. The long tom was used in areas where material needed to be moved some distance from the digging site to where water was available. 2
Highbanker
A portable sluice box with a water pump that allows placer mining away from a water source. The pump delivers water from a creek or pond to the highbanker’s hopper; the operator feeds material into the hopper; the material and water flow through the sluice riffles for gold recovery. Highbankers can access richer placer reserves on benches above the water line that sluice boxes cannot reach. 2
Drywasher
A placer mining tool for use in arid desert environments where water is unavailable. The drywasher uses air (wind or a bellows) instead of water to separate gold from lighter material. Material is fed into a vibrating riffle box; air blown through the bottom lifts lightweight material away while gold falls through the riffles. The “bread and butter of desert prospecting” – used extensively in the Mojave Desert, Sonoran Desert, and other arid gold districts. 2
Dredge (Bucket Line Dredge)
A floating mining platform that excavates placer material from a pond or river, processes it through an onboard plant (trommel + sluice), and deposits tailings behind as it advances. Dredges are the largest-scale placer mining equipment, capable of processing thousands of cubic meters per day. Historic bucket line dredges were massive machines – the gold dredges of the Klondike (Yukon) and Atlin (BC) operated from the 1890s through the 1960s, leaving characteristic tailings windrows visible from satellite imagery today. 2
Shaker Table
A gravity separation device that uses vibration and water flow across a riffled deck to separate minerals by density. The shaker table is essentially a giant gold pan – heavy gold particles migrate to one side of the vibrating table while lighter material flows off the other. Shaker tables are used for fine gold recovery and concentration of heavy mineral sands. 2
Flumes
Wooden or metal troughs used to transport water over terrain where a ditch would be impossible (cliff sides, rocky hillsides). Flumes were essential infrastructure for large-scale California hydraulic mining operations – delivering high-pressure water from mountain sources to the mining monitors. Some historic flumes ran for tens of miles through rugged terrain. 2
Flour Gold / Gold Dust
Gold that is so fine it looks and feels like flour or dust – tiny particles, often sub-millimeter, that behave almost like liquid rather than solid gold. Flour gold is extremely difficult to recover with conventional sluices because it can be carried by water turbulence rather than settling. Recovery requires fine riffles, low water velocity, and sometimes chemical treatment (mercury amalgamation historically; modern alternatives include fine recovery systems). Flour gold is extremely common in glaciated placer terrains. 2
Sourdough
A highly experienced miner or prospector who has worked in the gold fields for many years. The term originated in the Klondike Gold Rush, where experienced miners survived the harsh winters by keeping sourdough starter (for bread) alive – a metaphor for their hardiness and self-sufficiency. 2
Pack Train
A group of horses or mules (typically five or more) with handlers used to transport supplies and equipment to remote mining sites in the 19th and early 20th centuries. Pack trains were essential to reaching high-elevation mines in the Sierra Nevada, Rockies, and Coast Mountains before road access was established. Modern equivalents include helicopter sling loads and all-terrain vehicles. 2
Key geological periods relevant to mining and mineral exploration:
Pre-Cambrian. Older than 541 million years ago. Many of the world’s largest gold, iron ore, and nickel deposits formed in Pre-Cambrian rocks (e.g. Witwatersrand gold, Pilbara iron ore, Sudbury nickel)
Cambrian. 541–485 million years ago. The earliest period of the Paleozoic era
Paleozoic Era. 541–252 million years ago. Encompasses Cambrian through Permian periods
Devonian. 419–359 million years ago. Important for VHMS (volcanogenic massive sulfide) copper-zinc deposits
Permian. 299–252 million years ago
Cretaceous. 145–66 million years ago. Many porphyry copper-gold deposits (Andes, North American Cordillera) formed in this period
Tertiary. 66–2.6 million years ago. Epithermal gold-silver deposits (Nevada, Central America) predominantly Tertiary age
Quaternary. 2.6 million years ago to present. The dominant age of placer gold, diamond, and heavy mineral sand deposits
Source: General geology and Prosper Systems5
CAPEX / capex
Capital Expenditure – funds spent to acquire, construct, or improve long-term physical assets. In mining, capex includes mine construction, processing plant, infrastructure, and sustaining capital to maintain production capacity. Capex is a primary determinant of project economics and a key focus of mining project feasibility studies. 5
Coyote Holes
Small excavations or tunnels dug by individual prospectors to follow a gold-bearing vein or placer deposit underground – named for the small, erratic excavations a coyote makes searching for prey. Coyote holes were common in early California and Nevada mining and represent the simplest form of underground hard rock mining. 2
Disclosure
The public release of material information about a mining company’s mineral projects. Under securities regulations (NI 43-101 in Canada, Regulation S-K 1300 in the US), companies must disclose all material scientific and technical information about their mineral projects in a timely, accurate, and balanced manner. Selective or misleading disclosure is a securities violation. 4
Exploration Information / Written Disclosure
All oral statements and written documents (news releases, technical reports, websites, investor presentations) containing scientific or technical information about a mineral project that a reasonable investor would consider important in making an investment decision. Under NI 43-101, all exploration information must be based on a Qualified Person’s advice. 4
Mineral Project
A specific mineral property or group of mineral properties for which a mining company is conducting exploration, development, or production activities. A mining company may have multiple mineral projects in its portfolio at various stages of advancement. 4
Professional Association
A recognized professional body whose members are bound by a code of ethics and are subject to disciplinary action for conduct resulting in a conviction of a criminal offense or professional misconduct. NI 43-101 requires Qualified Persons to be members of a recognized professional association. Examples include: Association of Professional Engineers and Geoscientists of British Columbia (APEGBC), Professional Engineers Ontario (PEO), Society of Mining, Metallurgy and Exploration (SME). 4
Basal Till
Clay and debris deposited at the base of a glacier as it moves. Basal till is important in placer and glacial deposit geology because it can concentrate heavy minerals including gold, diamonds, and indicator minerals for kimberlite (diamond pipe) exploration. Glacial dispersal trains of indicator minerals are used to back-track to the source of diamond-bearing kimberlites. 2
Bituminous Coal
A middle-rank coal formed by heat and pressure on lower-rank lignite. Bituminous coal typically has a high BTU (British Thermal Unit) calorific value and is sometimes known as soft coal. It is the most widely mined coal type globally, used for both electricity generation (thermal coal) and steel production (metallurgical or coking coal). Metallurgical coal commands a significant premium over thermal coal due to its essential role in the steelmaking blast furnace process. 5
APPENDIX – ELEMENT SYMBOLS, GOLD FACTS & MEASUREMENTS
Common Mining Element Symbols
Element
Symbol
Magnesium
Mg
Aluminium
Al
Cobalt
Co
Nickel
Ni
Copper
Cu
Molybdenum
Mo
Rhodium
Rh
Palladium
Pd
Silver
Ag
Cadmium
Cd
Indium
In
Tantalum
Ta
Tungsten
W
Iridium
Ir
Platinum
Pt
Mercury
Hg
Gold
Au
Karat
Fineness
Gold %
24k
999.9
99.99%
22k
916.7
91.67%
18k
750
75.00%
14k
585
58.50%
10k
417
41.70%
9k
375
37.50%
Gold Weight
Equivalence
1 Troy Ounce (ozt)
31.1035 grams
1 Troy Ounce (ozt)
480 grains
1 Troy Ounce (ozt)
20 pennyweight (dwt)
1 Kilogram
32.1507 troy oz
1 Tonne
32,150.7 troy oz
1 Standard Bar
≈ 400 troy oz (12.4 kg)
A Bit About Gold
Gold is the most malleable and ductile of all metals. One troy ounce of gold can be beaten into a sheet covering 300 square feet, or drawn into 50 miles of wire. Gold is an excellent conductor of electricity and heat. It is chemically inert – it does not react with oxygen, most acids, or most reagents – which is why it does not tarnish or corrode. Gold is a good reflector of infrared radiation, making it valuable for spacecraft thermal protection and electronic contacts. Pure gold is too soft for most practical uses and is typically alloyed with silver, copper, or platinum to increase strength and hardness. 1
Specific Gravity of Key Minerals
Specific gravity is the ratio of a mineral’s weight to the weight of an equal volume of water (water = 1.0; 8.34 lbs per imperial gallon):
Mineral
Specific Gravity
Significance
Quartz (gangue)
2.65
Common waste mineral
Pyrite (fool’s gold)
5.0
Gold indicator
Galena (lead)
7.6
Lead ore
Magnetite
5.2
Iron ore, indicator
Cassiterite (tin)
7.0
Placer tin ore
Native Silver
10.5
Precious metal
Native Gold
15.0–19.3
Lower when alloyed
Pure Gold
19.3
Densest common metal
Platinum
21.4
Densest element (solid)
The high specific gravity of gold (19.3) is 7× denser than quartz – this density difference is the physical basis for all gravity separation methods (panning, sluicing, shaker tables). 1,5
JuniorMiners.com. A primary source for this glossary. Resource for junior mining company research, exploration news, and mining terminology. Covers TSX Venture and ASX-listed junior explorers. 1
ProspectorsParadise.com. A source for placer mining terminology and prospecting methods. Covers gold panning, sluicing, dredging, and historical placer mining techniques. 2
CIM Definition Standards for Mineral Resources and Mineral Reserves. The authoritative source for NI 43-101 compliant resource and reserve classification. Essential reading for anyone evaluating Canadian-listed mining companies or commissioning Technical Reports. Canadian Institute of Mining, Metallurgy and Petroleum4
JORC Code 2012. The Australian equivalent of NI 43-101 – governing resource and reserve reporting for ASX-listed mining companies. The JORC Code was the model for many international reporting standards. Joint Ore Reserves Committee (JORC)4
SEC Regulation S-K 1300 – Mining Property Disclosure. The SEC’s modernized mining disclosure standard, replacing Industry Guide 7 and aligning US disclosure with international standards (NI 43-101, JORC). Effective for fiscal years beginning January 1, 2021. US Securities and Exchange Commission4
Prosper Systems Oil & Gas. Covers drilling, reservoir, production, reserves, and regulatory terms for the petroleum industry – many concepts parallel mining (exploration phases, reserves classifications, royalties, farm-ins). Prosper Systems5
Prosper Systems Funding. Capital formation terms for natural resources investors – accredited investor rules, GP/LP structures, and Regulation D exemptions applicable to mining project financing. Prosper Systems5
Oil & Gas – Drilling, reservoir, production, reserves classification, royalties, and working interest terms for the upstream petroleum industry.
Commodities – Incoterms, letters of credit, shipping documents, and trade finance instruments for physical commodity transactions — the market layer for Oil & Gas and Mining output.
Funding – Capital formation, SEC exemptions, accredited investors, GP/LP structures, and syndication mechanics — the financial engine behind every sector.
Sales – Bank Guarantees, SBLCs, MTNs, SWIFT MT760/MT799, and trade finance instruments — the transaction layer for large asset and commodity deals.
Real Estate – Cap rates, NOI, pro forma, capital stack, REIT, leasing structures, and investment return metrics that underpin CRE financing decisions.
AI – Terms, tools, and deployment strategies for AI in CRE, AEC, and natural resources practice — the technology layer running across all PS sectors.
Neither Prosper Systems (PS), nor its Founder, Kenton H Johnson, are licensed Real Estate or Lending Brokers, Securities Dealers or Investment Advisers. However, PS has an Attorney on its Team, and works closely with and engages other licensed individuals or firms as needed. PS makes no warranties or representations as to the quality of an opportunity, the integrity of any party, or the value of a given transaction. PS is acting only as Collaborator. All due diligence is the responsibility of Investors, Buyers, Owners and their Collaborators.
The definitions in this Glossary are for guidance and educational purposes only and are not intended to be comprehensive or to constitute legal, financial, or investment advice. Resource and reserve estimates are subject to uncertainty – consult the relevant Technical Report and a Qualified Person before making investment decisions based on mineral project disclosures.
Prosper Systems, led by
Kenton H Johnson,
is a team of Business, Sales and Technical Operations Consultants
who have the resources and talents to work with projects and businesses that are or will be worth us$2M to $20M+, to facilitate:
Finance as Capital Consultants ala
Startup Steps,
or
Sale as Collaborators ala
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Prosper Systems is continuing to Collaborate with more Companies, Collaborators and Capital ala More Resources. Referrers are well compensated.
Mining Glossary