A nearly horizontal passage from the surface by which a mine is entered and dewatered. A blind horizontal opening into a mountain, with only one entrance.
An instrument used to measure magnetic field strength from an airplane.
A geophysical survey using a magnetometer aboard, or towed behind, an aircraft.
A survey made from an aircraft to obtain photographs, or measure magnetic properties, radioactivity, etc.
Any change in the mineralogic composition of a rock brought about by physical or chemical means, esp. by the action of hydrothermal solutions; also, a secondary, i.e., supergene, change in a rock or mineral. Alteration is sometimes considered as a phase of metamorphism, but is usually distinguished from it because of being milder and more localized than metamorphism is generally thought to be. Source: AGI
A departure from the expected or normal. A geological feature, esp. in the subsurface, distinguished bygeological, geophysical, or geochemical means, which is different from the general surroundings and is often of potential economic value; e.g., a magnetic anomaly.
To analyze the proportions of metals in an ore; to test an ore or mineral for composition, purity, weight, or other properties ofcommercial interest.
In determining the assay value of an ore body, the multiplication of its assay grade by the number of feet along which the sample was taken.
A weight of 29.166+ g, used in assaying to represent proportionately the assay value of an ore. Because it bears the same ratio to 1mg that a ton of 2,000 lb bears to the troy ounce, the weight in milligrams of precious metal obtained from an assay ton of ore equals the number of ounces to the ton. Abbrev. AT.
The annual work upon an unpatented mining claim on the public domain necessary under U.S.law for the maintenance of the possessory title there to. This work must be donee ach year if the claim is to be held without patenting.
Acceptable to lenders as basis for financing a project; most often used to describe definitive feasibility studies.
In plural form, a classification of metals usually considered to be of low value and higher chemical activity when compared with the noble metals (gold, silver, platinum, etc.). This non-specific term generally refers to the high-volume, low-value metals copper, lead, tin, and zinc.
The arrangement of a sedimentary rock in beds or layers of varying thickness and character.
Loosely used to describe a large scale regional shear zone or structural fault.
Rock composed of sharp-angled fragments embedded in a fine-grained matrix.
Bulk Mining/Bulk Tonnage
A method of mining in which large quantities of low-grade ore are mined without attempt to segregate the high-grade portions.
A regular series of ore chips or rock chips taken either in a continuous line across an exposure or at uniformly spaced intervals.
Portion of land held either by a prospector or a mining company. In Canada, the common size is 1,320 ft. (about 400 m) square, or 40 acres (about 16 ha).
A mineralization body inside a vein with small dimensions and high grades.
An ore containing two or more metals, as lead-zinc ore. Many complex ores are difficult or costly to treat, e.g., gold ore with arsenic orantimony minerals, or ore composed almost entirely of several sulfide minerals.
The long cylindrical piece of rock, about an inch in diameter, brought to surface by diamond drilling.
The lowest grade of mineralized material that qualifies asore in a given deposit; rock of the lowest assay included in an ore estimate.
A process of extracting gold and silver as cyanide slimes from their ores by treatment with dilute solutions of potassium cyanide or sodium cyanide. The slimes are subsequently fused and cast into ingots or bullion.
A body of rock containing valuable minerals; usage generally restricted to zones of mineralization whose size has been wholly or partly determined through sampling.
Drilling to establish accurate estimates of mineral reserves
A drilling machine with a rotating, hollow, diamond-studded bit that cuts a circular channel around a core, which can be recovered to provide a more or less continuous and complete columnar sample of the rock penetrated.
The angle at which a bed, stratum, or vein is inclined from the horizontal, measured perpendicular to the strike and in the vertical plane.
The art of drilling a borehole wherein the course of the hole is planned before drilling. Such holes are usually drilled with rotary equipment and are useful in drilling divergent tests from one location, tests that otherwise might be inaccessible, as controls for fire and wild wells, etc.
Ore carrying small particles of valuable minerals spread more or less uniformly through the host rock.
A steep-sided mass of viscous (doughy) lava extruded from a volcanic vent (often circular in plane view) and spiny, rounded, or flat on top. Its surface is often rough and blocky as a result of fragmentation of the cooler, outer crust during growth of the dome.
A horizontal opening in or near an ore body and parallel to the course of the vein or the long dimension of the ore body.
The size and quality of a potential ore body as suggested by widely spaced drillholes; more work is required before reserves can be classified as probable or proven.
A geophysical survey method which measures the electromagnetic properties of rocks.
Roughly parallel but staggered structures.
A mineral deposit consisting of veins and replacement bodies, usually in volcanic or sedimentary rocks, containing precious metals or, morerarely, base metals.
A curve or bend of a planar structure such as rock strata, bedding planes, foliation, or cleavage. A fold is usually a product of deformation, although its definition is descriptive and not genetic and may include primary structures.
An isometric mineral, 4[PbS]; cubic cleavage; forms cubes andoctahedra, also coarse- or fine-grained masses; sp gr, 7.6; occurs with sphalerite in hydrothermal veins, also in sedimentary rocks as replacement deposits; an important source of lead and silver. Also spelled galenite.
The study of the relative and absolute abundances of the elements and their nuclides (isotopes) in the Earth; the distribution and migration of the individual elements or suites of elements in the various parts of the Earth (the atmosphere, hydrosphere, lithosphere, etc.), and in minerals and rocks, and also the study of principles governing this distribution and migration. Geochemistry may be defined very broadly to include all parts of geology that involve chemical changes, or it may be focused more narrowly on the distribution of the elements, as in Mason's definition; the latter is commonly understood if the term is used without qualification.
A branch of physics dealing with the Earth, including its atmosphere and hydrosphere. It includes the use of seismic, gravitational, electrical, thermal, radiometric, and magnetic phenomena to elucidate processes of dynamical geology and physical geography, and makes use of geodesy, geology, seismology, meteorology, oceanography, magnetism, and other Earth sciences in collecting and interpreting Earth data. Geophysical methods have been applied successfully to the identification of underground structures in the Earth and to the search for structures of a particular type, as, for example, those associated with oil-bearing sands.
A methodology for the analysis of spatially correlated data.The characteristic feature is the use of variograms or related techniques to quantify and model the spatial correlation structure. Also includes the various techniques such as kriging, which utilize spatial correlation models.
The exploration of an area in which geophysical properties and relationships unique to the area are mapped by one or more geophysical methods.
A sample from a rock outcrop that is assayed to determine if valuable elements are contained in the rock. A grab sample is not intended to be representative of the deposit, and usually the best looking material is selected.
The relative quantity or the percentage of ore-mineral or metal content in an ore body.
High Grade Ore
Rich ore. As a verb, it refers to selective mining of the be store in a deposit.
A process used for the recovery of copper, uranium, and preciousmetals from weathered low-grade ore. The crushed material is laid on a slightly sloping, impervious pad and uniformly leached by the percolation of the leach liquor trickling through the beds by gravity to ponds. The metals are recovered by conventional methods from the solution.
An up faulted block of rock.
The rock surrounding an ore deposit.
Relating to hot fluids circulating in the earth’s crust.
Rock formed by the solidification of molten material that originated within the earth.
Resources from which the quantity and grade and/or quality ar ecomputed from information similar to that used for measured resources, but the sites for inspection, sampling, and measurement are farther apart or are otherwise less adequately spaced. The degree of assurance, although lower than that for measured resources, is high enough to assume continuity between points of observation.
Resources from which estimates are based on an assumed continuity beyond measured and/or indicated resources, for which there is geologic evidence. Inferred resources may or may not be supported by samples ormeasurements.
A mass of igneous rock that, while molten, was forced into orbetween other rocks.
A sedimentary rock consisting chiefly of calcium carbonate.
A brown, hydrous iron oxide.
A body of rock made up mainly or wholly of sulphide or chalcopyrite; often proves to be an ore body. Also, a mineral deposit occurring in massive-sulphide form.
Resources from which the quantity is computed from dimensions revealed in outcrops, trenches, workings, or drill holes; grade and/or qualityare computed from the results of detailed sampling. The sites for inspection, sampling, and measurement are spaced so closely and the geologic character isso well defined that size, shape, depth, and mineral content of the resourceare well established.
The science and art of separating metals and metallic minerals from their ores by mechanical and chemical processes; the preparation of metalliferous materials from raw ore.
Any ore that contains sufficient valuable minerals to be treated by any milling process.
The process or processes by which a mineral or minerals are introduced into a rock, resulting in a valuable or potentially valuable deposit. It is a general term, incorporating various types; e.g., fissure filling, impregnation, and replacement.
Ore reserves that are known to be extractable using a given mining plan.
A naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystalform, and physical properties.
Net Smelter Return
A share of the net revenues generated from the sale of metal produced by a mine.
A mine that is entirely on surface. Also referred to as open-cut or open-cast mine.
The naturally occurring material from which a mineral or minerals of economic value can be extracted profitably or to satisfy social or political objectives. The term is generally but not always used to refer to metalliferous material, and is often modified by the names of the valuable constituent; e.g., iron ore.;ore mineral.
A vertical or inclined passage for the downward transfer of ore; equipped with gates or other appliances for controlling the flow. An ore pass is driven in ore or country rock and connects a level with the hoisting shaft or with a lower level.
A continuous, well-defined mass of material of sufficient ore content to make extraction economically feasible.
The term is usually restricted to ore of which the grade and tonnage have been established with reasonable assurance by drilling and other means.
An elongate pipelike, ribbon like, or chimney like mass of ore within a deposit (usually a vein), representing the more valuable part of the deposit.
The part of a rock formation that appears at the surface of the ground.
An exceptionally coarse-grained igneous rock, with interlocking crystals, usually found as irregular dikes, lenses, or veins, esp. at themargins of batholiths. Most grains are 1 cm or more in diameter. Although pegmatites having gross compositions similar to other rock types are known,their composition is generally that of granite; the composition may be simple or complex and may include rare minerals rich in such elements as lithium, boron, fluorine, niobium, tantalum, uranium, and rare earths. Pegmatites represent the last and most hydrous portion of a magma to crystallize and hencecontain high concentrations of minerals present only in trace amounts ingranitic.
An igneous rock of any composition that contains conspicuous phenocrysts in a fine-grained groundmass; a porphyritic igneous rock. The term(from a Greek word for a purple dye) was first applied to a purple-red rock quarried in Egypt and characterized by phenocrysts of alkali feldspar. The rock name descriptive of the groundmass composition usually precedes the term; e.g., dioriteporphyry. Obsolete syn: porphyrite.
A large body of rock, typically porphyry, that contains disseminated chalcopyrite and other sulfide minerals. Such deposits are mined in bulk on a large scale, generally in open pits, for copper and byproduct molybdenum. Most deposits are 3 to 8 km across, and of low grade (less than 1%Cu). They are always associated with intermediate to felsic hypabyssalporphyritic intrusive rocks. Distribution of sulfide minerals changes outward from dissemination to veinlets and veins. Supergene enrichment has been very important at most deposits, as without it the grade would be too low to permitmining.
A mineral occurrence that is being, or has been, explored; often restricted to mineral occurrences that have been drilled.
Reserves that have been sampled extensively by closely spaced diamond drill holes and possibly developed by underground workings in sufficient detail to render an accurate estimation of grade and tonnage.
An isometric mineral, FeS2; dimorphous withmarcasite; forms a series with cattierite; crystallizes in cubes andpyritohedra; sparks readily if struck by steel; metallic; pale bronze to brass yellow; hardness varies from 6.0 to 6.5; occurs in veins, as magmatic segregation, as accessory in igneous rocks, and in metamorphic rocks, in sedimentary rocks including coal seams; a source of sulfur; may have includedgold.
A general, exploratory examination or survey of the main features (or certain specific features) of a region, usually conducted as a preliminary to a more detailed survey; e.g. an engineering survey in preparing for triangulation of a region. It may be performed in the field or office, depending on the extent of information available.
The percentage of valuable metal in the ore that is recovered by metallurgical treatment.
The quantity of mineral that is calculated to lie within given boundaries. It is described as total (or gross), workable, or probable working,depending on the application of certain arbitrary limits in respect of deposit thickness, depth, quality, geological conditions, and contemporary economic factors. Proved, probable, and possible reserves are other terms used ingeneral mining practice.
The calculated amount of material in a mineral deposit, based on imited drill information.
A drilling method in which rotating bit cuts rock or compacted earth into fragments, which are flushed upward to the drill collor.
The extrusive equivalent of granodiorite. The principal minerals, sodic plagioclase, sanidine, quartz, and biotite or hornblende, commonly occur as phenocrysts in a finely crystalline groundmass of alkali feldspar and quartz. Accessory minerals are apatite and magnetite, and occasionally augite.
A group of extrusive igneous rocks, typically porphyritic and commonly exhibiting flow texture, with phenocrysts of quartz and alkalifeldspar in a glassy to cryptocrystalline groundmass; also, any rock in that group; the extrusive equivalent of granite. Rhyolite grades into rhyodacite with decreasing alkali feldspar content and into trachyte with a decrease inquartz. The term was coined in 1860 by Baron von Richthofen (grandfather of the World War I aviator). Etymol: Greek rhyo-, from rhyax, stream of lava.
A lease by which the owner or lessor grants to the lessee the privilege of mining and operating the land in consideration of the payment of a certain stipulated royalty on the mineral produced.
Representative fraction of body of material; removed by approved methods; guarded against accidental or fraudulent adulteration; and tested oranalyzed to determine the nature, composition, percentage of specified constituents, etc., and possibly their reactivity. Bulk samples are large(several tons), so taken as to represent the ore for the purpose of developinga suitable treatment. Channel samples, cores, chips, grab, pannings, stope samples, etc., are small ones - made primarily to establish the value of the ore reserve.
The gathering of specimens of ore or wall rock for appraisal ofan ore body. Since the average of many samples may be used, representative sampling is crucial. The term is usually modified to indicate the mode orlocality; e.g., hand sampling, mine sampling, and channel sampling.
An early stage study on the economics of a mining project used for development planning. It is generally based onassumptions and estimated costs, and is neither as detailed nor s reliable as afeasibility study (for a lender). May also be called a “preliminary economic assessment.
Enrichment of a vein or mineral deposit by minerals that have been taken into solution from one part of the vein or adjacent rocks and deposited in another.
Rocks formed by the accumulation of sediment in water (aqueousdeposits) or from air (eolian deposits). The sediment may consist of rock fragments or particles of various sizes (conglomerate sandstone, shale); of the remains or products of animals or plants (certain limestones and coal); of the product of chemical action or of evaporation (salt, gypsum, etc.); or of mixtures of these materials. Some sedimentary deposits (tuffs) are composed offragments blown from volcanoes and deposited on land or in water. Acharacteristic feature of sedimentary deposits is a layered structure known as beddingor stratification. Each layer is a bed or stratum. Sedimentary beds as deposited lie flat or nearly flat.
A vertical or inclined excavation in rock for the purpose of providing access to an ore body. Usually equipped with a hoist at the top, which lowers and raises a conveyance for handling workers and materials.
The deformation of rocks by cumulative small lateral movements along innumerable parallel planes, generally resulting from pressure, and producing schistosity, cleavage, minute application, and other metamorphic structures.
The valuable minerals are commonly concentrated in certain portions of a vein that have one dimension much longer than the others. This shoot or chimney of ore is usually highly inclined to the horizontal.
A process of fossilization whereby the original organic components of an organism are replaced by silica, as quartz, chalcedony, or opal. Source: AGI
Name for the metamorphic rocks surrounding an igneous intrusive where it comes in contact with a limestone or dolostone formation.
Holes drilled to intersect a mineralization horizon or structure along strike or down dip.
The direction, or bearing from true north, of a vein or rock formation measured on a horizontal surface.
The unit amount of spoil or overburden that must be removed to gain access to a unit amount of ore or mineral material, generally expressed in cubic yards of overburden to raw tons of mineral material.
Material rejected from a mill after most of the recoverable valuable minerals have been extracted.
In metallurgy, a unit of mass equal to one percent of a ton; thus if an ore assays 3% metal, one "unit" may be based on contained metal, or on the contained oxide unit is equal to 20 LB., along to (or "tonne unit"), 10 KG. Occasionally used in smelting contracts, or in pricing some ores.
In geological exploration, a narrow, shallow ditch cut across a mineral deposit to obtain samples or to observe character.
The direction, in the horizontal plane, of a linear geological feature, such as an ore zone, measured from true north.
A rock fissure filled by intruded mineral matter that has travelled upwards form some deep source.
A generally finely crystalline or glassy igneous rock resulting from volcanic action at or near the Earth's surface, either ejected explosively or extruded as lava; e.g., basalt. The term includes near-surface intrusions that form a part of the volcanic structure.
A steep-sided extrusion of very viscous lava that is squeezed from a volcanic vent without major eruption. These are frequently rhyolitic in composition and produce a rounded mound above the vent.
an area of distinct mineralization.
Zone of oxidation
the upper portion of an ore body that has been oxidized.