All-in Sustaining Cost – Gold (AISC): According to the World Gold Council (WGC), All-in Sustaining Costs (AISC) are defined as: “A comprehensive measure of the full cost of sustaining current gold production, including operating costs, sustaining capital expenditures, and other costs related to maintaining production at existing levels.” For a detailed view on how Ero calculates gold AISC, please refer to the Non-IFRS Measures section of the most recent MDA.
Assay: Laboratory analysis to determine the metal content of ore or concentrate.
B
Ball Mill: A rotating horizontal cylindrical device used to grind ore into fine particles for processing.
Base Metals: Common industrial metals like copper, zinc, and nickel (excluding precious metals).
Brownfield Exploration: Exploration near or within an existing mine or infrastructure.
By-product: Secondary metal or mineral recovered during the production of a primary commodity.
C
C1 Cash Cost: Direct cash cost per unit of metal produced, excluding sustaining capital and corporate overhead. For a detailed view on how Ero calculates Cash Costs, please refer to the Non-IFRS Measures section of the most recent MDA.
Concentrate Sales: Sale of processed ore containing a high percentage of the target metal.
Contained Metal: Amount of metal present in ore or concentrate, before processing losses.
Copper Equivalent: A metric used to express the combined value of all metals in a deposit as an equivalent amount of copper. It converts the economic value of by-product metals (such as gold, silver, or molybdenum) into the amount of copper that would have the same value, based on current metal prices, recoveries, and applicable smelter or treatment charges. Copper Equivalent is commonly used to simplify reporting, compare deposits or projects, and assess the overall economic potential of polymetallic resources.
Copper Sold in Concentrate: Quantity of copper contained in concentrate delivered to buyers.
Core: Cylindrical rock sample extracted during drilling for analysis.
Cut-off Grade: Minimum metal grade at which ore is economically mined and processed.
D
Depletion: Reduction of mineral reserves due to mining production.
Deposit: Naturally occurring accumulation of minerals that can be economically extracted.
Development: Work to prepare a mine for production, including tunnels, shafts, and infrastructure.
Dilution: Waste material mixed with ore during mining, lowering the average grade.
Doré: Unrefined gold and/or silver bars produced at a mine before refining.
Dry Stacking: Tailings disposal method that involves dewatering tailings to higher degrees than a paste consistency for storage in a dry stack.
F
Flotation: Process to separate valuable minerals from ore using chemical reagents.
G
Grade: Metal content of ore, expressed as a percentage or grams per tonne.
Greenfield Exploration: Exploration in an area with no prior mining history.
L
Life of Mine (LOM): Estimated period a mine will operate based on the current mine plan.
N
NI 43-101: National Instrument 43-101 (the “NI 43-101” or “NI”) is a Canadian regulatory standard governing the disclosure of information for mineral projects. It provides a codified set of rules and guidelines for reporting and presenting details about mineral properties owned or explored by companies listed on Canadian stock exchanges, including foreign-owned mining companies that trade on exchanges regulated by the Canadian Securities Administrators.
O
Ore Mined: Quantity of ore extracted from the mine.
Ore Processed: Quantity of ore sent through the plant for metal recovery.
P
Paste Fill: Mixture of tailings and cement used to fill mined-out areas underground.
R
Reserves: Mineral Reserves represent the economically mineable portion of a Measured or Indicated Mineral Resource. In other words, they’re the part of a resource that has been evaluated in enough detail – including mining, processing, metallurgical, economic, and legal factors – to demonstrate that extraction can be done economically under current conditions. Before a Resource can be classified as a Reserve, it must go through technical and economic studies (like a feasibility or pre-feasibility study) that apply Modifying Factors — things like mining methods, recovery rates, operating costs, environmental and permitting considerations, and market assumptions.
Probable: Derived from Indicated (and sometimes Measured) Resources, Probable Reserves carry a reasonable level of confidence in the economic and technical factors supporting extraction. Some uncertainty remains, but studies show that mining is likely to be economically viable.
Proven: Derived from Measured Resources, Proven Reserves have the highest level of confidence. The deposit’s size, grade, and modifying factors have been confirmed through detailed studies, and the economic case for mining is strong and well supported.
Resources: Mineral Resources are sub-divided, in order of increasing geological confidence, into inferred, indicated and measured categories. A Mineral Resource is a concentration or occurrence of solid material of economic interest in or on the earth’s crust in such form, grade or quality and quantity that there are reasonable prospects for eventual economic extraction. The location, quantity, grade or quality, continuity and other geological characteristics of a Mineral Resource are known, estimated or interpreted from specific geological evidence and knowledge, including sampling.
Inferred: This is the earliest stage of resource confidence. The deposit is believed to exist based on limited geological information – such as a few drill holes or samples – but there’s still a lot of uncertainty about its size, grade, and shape. More drilling and data are needed to confirm its extent and quality.
Indicated: At this stage, there’s moderate confidence in the data. The deposit has been drilled and sampled enough to reasonably estimate its size, grade, and physical characteristics. There’s sufficient information to start preliminary mine planning and assess whether extraction might be economically viable, though some uncertainty remains. An Indicated Mineral Resource has a lower level of confidence than that applying to a Measured Mineral Resource and may only be converted to a Probable Mineral Reserve.
Measured: The deposit has been thoroughly explored, sampled, and modeled. The geological characteristics are well understood, allowing for detailed mine design and reliable economic evaluation. A Measured Mineral Resource has a higher level of confidence than that applying to either an Indicated Mineral Resource or an Inferred Mineral Resource. It may be converted to a Proven Mineral Reserve or to a Probable Mineral Reserve.
S
Shaft: Vertical or inclined tunnel used to access underground ore.
Smelting: Process of extracting metal from concentrate by heat and chemical reduction.
Stockpile: Accumulated ore or concentrate stored before processing or shipment.
Stope: Underground excavation where ore is extracted.
Strip Ratio: Ratio of waste rock to ore in an open-pit mine.
T
Tailings: Residual waste from ore processing.
V
Vein: Mineralized zone or fracture in rock containing valuable metals.
W
Waste: Material removed during mining that does not contain economically recoverable metals.