Gold Mines Industry Terminology
Acid mine drainage (AMD)
Acidic, metal-laden water produced when sulfide minerals (e.g., pyrite) oxidize upon exposure to air and water; a major environmental risk at waste rock piles, tailings, and underground workings.
- 'Our closure plan includes a water treatment plant to neutralize AMD from waste rock dumps.' - 'Lime dosing costs for AMD mitigation are built into the AISC.' - 'The EIA baseline shows elevated sulfate downstream, indicating potential AMD pathways.'
All-in sustaining cost (AISC)
A standardized, per-ounce cost metric capturing site cash costs plus sustaining capital, corporate G&A, reclamation accretion, and sustaining exploration; excludes growth capex and financing.
- 'Company X guided AISC of $1,250/oz for FY25.' - 'Switching to a solar-diesel hybrid cuts AISC by roughly $40/oz.' - 'We benchmark in the second cost quartile on AISC.'
Alteration halo
A mineralogical and chemical footprint around an ore zone caused by hydrothermal fluids, often including silicification, sericitization, argillic and propylitic alteration; used to vector toward mineralization.
- 'The sericite-silica alteration halo vectors toward the higher-grade core.' - 'Portable XRF mapping of alteration helps refine drill targeting.' - 'Argillic alteration intensifies near the vein swarm.'
Artisanal and small-scale mining (ASM)
Informal to semi-formal mining by individuals or small groups, often with rudimentary methods; significant for livelihoods but can pose safety, environmental, and mercury-use challenges.
- 'Our supply chain policy outlines due diligence for potential ASM-sourced doré.' - 'The NGO partnership supports ASM formalization and mercury reduction.' - 'ASM encroachment near our license requires proactive community engagement.'
Assay
Chemical analysis to determine gold content in samples, typically reported as grams per tonne (g/t); methods include fire assay and multi-element ICP.
- 'Fire assays returned 4.1 g/t Au over 12 m.' - 'Assay turnaround times improved to 10 days.' - 'We validated lab assays with umpire testing.'
Autoclave
A high-pressure, high-temperature vessel used in pressure oxidation (POX) to treat refractory gold ores by oxidizing sulfides prior to cyanidation.
- 'The POX autoclave oxidizes arsenian pyrite before CIL.' - 'Autoclave availability has stabilized at 92 percent.' - 'We modeled a second autoclave to de-bottleneck sulfide throughput.'
Backfill
Material used to refill mined-out underground stopes, ranging from loose waste to cemented paste; improves ground stability and can reduce surface tailings storage.
- 'Cemented paste backfill allows earlier pillar recovery and reduces tailings in the TSF.' - 'Backfill strength meets the stope design criteria.' - 'Switching to paste backfill cuts haulage costs and surface impacts.'
Bench
A step or ledge in an open-pit mine; bench height influences drill-blast design, equipment selection, and slope stability.
- 'The pit will be developed on 10 m benches with 30 m berm intervals.' - 'Drilling and blasting patterns are optimized per bench height.' - 'Bench scale geotech mapping informs slope design.'
Bullion
Refined precious metal bars or ingots, typically meeting Good Delivery specifications; distinguished from doré, which is impure.
- 'The refinery delivered London Good Delivery 400 oz bars.' - 'Bullion shipments are hedged during transit.' - 'Doré is refined to bullion before sale to the offtaker.'
By-product credit
Revenue from secondary metals (e.g., silver, copper) credited against operating costs or reported as gold-equivalent ounces, improving per-ounce cost metrics.
- 'Silver credits reduce our AISC by roughly $80/oz.' - 'We modeled copper by-product credits in the POX concentrate scenario.' - 'Payable zinc credits offset higher cyanide consumption.'
Carbon-in-leach (CIL)
A gold recovery process where leaching and adsorption onto activated carbon occur simultaneously in the same tanks.
- 'CIL was selected over CIP due to lower capital for our ore type.' - 'CIL residence time is 24 hours to achieve 93 percent recovery.' - 'Preg-robbing risk is mitigated with CIL and carbon management.'
Carbon-in-pulp (CIP)
A recovery process in which gold is first leached and then adsorbed onto carbon in a separate train of tanks; contrasted with CIL.
- 'Leach tanks precede a CIP adsorption train.' - 'CIP elution uses the Zadra process.' - 'CIP is preferred given the fine grind and low preg-robbing.'
Carlin-type deposit
Large, low-grade, disseminated gold deposits, commonly in Nevada, hosted in carbonate rocks with 'invisible gold' in arsenian pyrite; typically refractory.
- 'The ore is refractory, typical of Carlin-type systems.' - 'Trace arsenic in pyrite is a hallmark of Carlin mineralization.' - 'Oxide caps overlie deeper Carlin-type sulfide ore.'
Cash cost
Per-ounce operating cost including mining, processing, and site G&A but excluding sustaining capital and other non-operating items; less comprehensive than AISC.
- 'Cash cost is $900/oz, but AISC is $1,200/oz.' - 'We remain competitive on cash cost, though sustaining capex lifts AISC.' - 'Cash cost excludes corporate G&A and sustaining capital.'
Comminution
Size reduction of ore via crushing and grinding; energy-intensive step often using SAG, ball mills, or HPGR, strongly influenced by ore hardness.
- 'HPGR reduced specific energy versus SAG-ball.' - 'The ore is hard, with a high Bond Work Index driving power costs.' - 'Comminution accounts for the largest share of site energy use.'
Cut-off grade
The minimum grade at which material is economic to process, dependent on metal price, recovery, costs, and payability; used to classify ore versus waste.
- 'We optimized cut-off grade to maximize NPV.' - 'A higher gold price lowered the marginal cut-off.' - 'Stockpiles are managed based on dynamic cut-off strategies.'
Cyanide Code (International Cyanide Management Code)
A voluntary industry program for the safe manufacture, transport, and use of cyanide in gold mining, emphasizing auditing, training, and transparent reporting.
- 'Our operations are fully certified under the Cyanide Code.' - 'The transporter is a Code signatory and audited.' - 'Cyanide detoxification meets Code standards before discharge.'
Decline (ramp)
An inclined underground access tunnel used for vehicle and equipment access to ore zones; alternative or complement to shafts.
- 'The main decline is developed at a 1 in 7 gradient for truck access.' - 'Vent raises connect to the decline at each level.' - 'Decline advance averages 4.5 m per day.'
Dilution
Waste material unintentionally mined and mixed with ore, reducing feed grade and value; managed via design, drilling, blasting, and ore control practices.
- 'Unplanned dilution lowered head grade by 12 percent.' - 'Tighter blast control reduced dilution in narrow stopes.' - 'Our reconciliation model separates planned versus unplanned dilution.'
Doré
An impure gold-silver alloy produced on site prior to refining into bullion; typically cast into bars and shipped to a refinery.
- 'We poured 18 doré bars this month for shipment to the refinery.' - 'Doré averages 85–95 percent precious metals.' - 'Security protocols cover doré handling from furnace to vault.'
Drill intercept
A reported interval of mineralized drill results showing length and grade, often with start depth and whether widths are true or downhole; key for exploration updates.
- '20 m at 3.5 g/t Au from 120 m downhole' - 'We report true width where possible; otherwise we provide an estimated conversion.' - 'High-grade intercepts define a plunging shoot.'
Environmental impact assessment (EIA)
A formal study identifying and mitigating environmental and social impacts of a project, typically required for permitting and involving public consultation.
- 'The EIA baseline includes hydrology, biodiversity, and social data.' - 'We incorporated community feedback into the EIA mitigation plan.' - 'EIA approval is on the critical path for construction start.'
Epithermal deposit
Shallow to mid-crustal hydrothermal gold deposits, typically vein-hosted; include low-, intermediate-, and high-sulfidation styles with distinct alteration assemblages.
- 'Quartz-adularia veins indicate a low-sulfidation epithermal system.' - 'Vuggy silica suggests high-sulfidation alteration.' - 'Bonanza-grade shoots occur within the epithermal vein field.'
ESG (Environmental, Social, and Governance)
A framework for assessing environmental performance, social responsibility, and governance practices; increasingly tied to capital access and stakeholder support.
- 'Investors are asking for TCFD-aligned climate disclosures in our ESG report.' - 'Our ESG KPIs include TRIFR and water intensity.' - 'Community agreements are central to our ESG strategy.'
Feasibility study (FS)
A definitive engineering and economic study with detailed designs, schedules, and cost estimates, typically used for final investment decisions and project financing.
- 'The FS supports a 2.8 Mtpa plant over a 12-year LOM.' - 'Capex accuracy in the FS is within plus or minus 15 percent.' - 'The FS underpins conversion of resources to Proven and Probable reserves.'
Flotation
A mineral separation process using air bubbles and reagents to concentrate sulfide-associated gold, often producing a concentrate for POX or roasting.
- 'We float a pyrite concentrate for POX treatment.' - 'Xanthate collectors improved gold recovery into the sulfide concentrate.' - 'Flotation tails proceed to CIL for residual recovery.'
Forward sales (hedging)
Price risk management via forwards and options to lock in or protect gold prices for future production; trades off upside for revenue certainty.
- 'We layered forward sales at $2,200/oz to secure debt covenants.' - 'A zero-cost collar protects downside but caps upside.' - 'Hedge book mark-to-market is disclosed quarterly.'
Free cash flow (FCF)
Cash generated after operating expenses and capital expenditures; key for deleveraging, dividends, and buybacks.
- 'Higher grades in H2 boost FCF and allow debt prepayment.' - 'Our dividend policy targets 30 percent of FCF.' - 'Sustaining capex timing affects quarterly FCF volatility.'
Geometallurgy
Integration of geology, metallurgy, and mine planning to model spatial variability in throughput, recovery, and deleterious elements for optimized value.
- 'Recovery penalties in the arsenic-rich domain are built into the geo-met model.' - 'We linked hardness and recovery to the block model for scheduling.' - 'Geomet data supports ore sorting decisions.'
Geostatistics
Statistical methods for spatial data analysis and estimation, including variograms, kriging, and simulations to model grade distribution and uncertainty.
- 'Variography shows strong anisotropy along the vein strike.' - 'Ordinary kriging was used for the resource model.' - 'Multiple indicator simulation captures grade uncertainty.'
Gold equivalent (AuEq)
A metric converting by-product metals into gold units using price and recovery assumptions to express aggregate metal value; assumptions must be disclosed.
- 'We report AuEq using $1,900/oz Au and $24/oz Ag with stated recoveries.' - 'By-product copper increases AuEq head grade.' - 'Disclosure includes AuEq calculation assumptions per NI 43-101.'
Grade
The concentration of gold in ore, commonly reported in grams per tonne; key driver of revenue, recovery, and unit costs.
- 'Head grade averaged 2.1 g/t this quarter.' - 'Selective mining reduced dilution and lifted mill feed grade.' - 'Reserve grade is higher than resource grade due to cut-off selection.'
Heap leach
A low-capex process stacking crushed ore on lined pads and irrigating with cyanide solution to dissolve gold, recovered via adsorption-desorption-recovery (ADR).
- 'The oxide ore will be processed via heap leach and ADR plant.' - 'Cold climate requires solution heating for winter leaching.' - 'Pad stacking rates determine leach cycle times.'
High-grade
Relative term describing ore with significantly above-average gold content for the deposit and mining method; often the focus of early scheduling.
- 'The high-grade shoot plunges to the southeast.' - 'A 20 g/t cutoff was used to cap extreme high grades in estimation.' - 'High-grade lenses drive early cash flow in the mine schedule.'
Indicated resource
A mineral resource category with sufficient geological confidence for mine planning studies; can be converted to Probable reserves with appropriate modifying factors.
- 'Indicated resources support PFS-level mine planning.' - 'Drill density improved confidence from Inferred to Indicated.' - 'We converted part of Indicated to Probable reserves.'
Inferred resource
The lowest-confidence mineral resource category; based on limited geological evidence and not suitable for reserve conversion or detailed economic modeling.
- 'Inferred ounces are excluded from the production schedule.' - 'Follow-up drilling aims to upgrade Inferred to Indicated.' - 'NI 43-101 restricts using Inferred for economic analysis.'
Internal rate of return (IRR)
The discount rate that sets a project’s net present value to zero; a key investment metric alongside NPV and payback.
- 'The FS shows a post-tax IRR of 21 percent at $1,850/oz.' - 'IRR is most sensitive to gold price and head grade.' - 'We target an IRR above 15 percent for greenfield projects.'
JORC Code
Australasian code governing public reporting of exploration results, mineral resources, and ore reserves, requiring Competent Person sign-off and transparent disclosure.
- 'Resources and reserves are reported to the 2012 JORC Code.' - 'A Competent Person signed off on the JORC Table 1.' - 'Our dual-listing requires JORC and NI 43-101 alignment.'
Joint venture (JV)
A partnership structure to share risk, capital, and expertise across companies; may include operatorship, earn-in terms, and dilution provisions.
- 'We operate the JV at 60 percent, partner holds 40 percent.' - 'The earn-in JV requires $15M of spend over four years.' - 'JV terms include dilution for non-participation.'
Kriging
A geostatistical interpolation method providing the best linear unbiased estimate of block grades based on spatial continuity models.
- 'Ordinary kriging smoothed high-grade spikes; we applied top cuts.' - 'Kriging variance guided classification to Inferred and Indicated.' - 'Search ellipses reflect structural anisotropy.'
Leach pad
An engineered, lined facility for stacking ore in heap leach operations, designed to contain solutions and prevent seepage to the environment.
- 'The pad uses double HDPE liners with leak detection.' - 'Stack heights are limited by slope stability analysis.' - 'We plan a westward pad expansion in Year 3.'
Life-of-mine (LOM)
The total planned duration and production profile of a mine, underpinned by reserves and a scheduling model; used for economic, ESG, and closure planning.
- 'The LOM plan delivers 2.0 Moz over 11 years.' - 'LOM strip ratio averages 5.2 to 1.' - 'LOM closure costs are provisioned in our accounts.'
Mineral reserve
The economically mineable part of Measured and/or Indicated resources, classified as Probable or Proven after applying modifying factors and appropriate studies.
- 'Reserves increased to 1.8 Moz Proven and Probable.' - 'Reserve conversion followed completion of the FS.' - 'Modifying factors like dilution and recoveries are applied to reserves.'
Mineral resource
A concentration of mineralization with reasonable prospects for eventual economic extraction, classified as Measured, Indicated, or Inferred based on confidence.
- 'Measured and Indicated resources total 3.5 Moz.' - 'Resources are reported above a 0.5 g/t cutoff.' - 'Reasonable prospects for eventual economic extraction must be demonstrated.'
Net present value (NPV)
The sum of discounted future cash flows, typically at the company’s weighted average cost of capital or a project-specific hurdle rate; central to investment decisions.
- 'Post-tax NPV at 5 percent is $620M.' - 'NPV sensitivity is strongest to gold price and grade.' - 'We discounted at WACC to derive NPV.'
NI 43-101
Canadian securities standard governing public disclosure of scientific and technical information on mineral projects, requiring Qualified Person oversight and formal technical reports.
- 'Our technical report is compliant with NI 43-101.' - 'A Qualified Person must approve material scientific disclosures.' - 'We filed the 43-101 within 45 days of the news release.'
Open pit
A surface mining method extracting ore from a series of benches and phases, governed by geotechnical, economic, and scheduling constraints.
- 'Pushbacks are designed to optimize cash flow.' - 'Overall slope angles reflect geotechnical domains.' - 'The Whittle shells guided ultimate pit limits.'
Orebody
A three-dimensional volume of rock containing economically extractable mineralization, defined by geometry, grade, continuity, and geomet characteristics.
- 'The orebody is a steeply dipping quartz vein system.' - 'Orebody continuity improves along the anticline hinge.' - 'Orebody knowledge is central to dilution control.'
Royalty
A financial interest granting the holder a share of revenue or profit from production, commonly Net Smelter Return (NSR), Gross Royalty, or Net Profits Interest (NPI).
- 'The project carries a 2 percent NSR royalty payable to the vendor.' - 'We negotiated a royalty buyback to improve project NPV.' - 'Streaming and royalties affect the effective tax and cash cost.'
Tailings storage facility (TSF)
An engineered structure for storing tailings; designs include upstream, downstream, and centerline, with increasing adoption of filtered and dry-stacked tailings for risk reduction.
- 'We are transitioning to filtered tailings to reduce TSF risk.' - 'The TSF is designed to the global industry standard on tailings management.' - 'Instrumentation monitors pore pressures and dam performance.'
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