glossary

Au: Gold

Ag: Silver

alteration: A change in the chemical and mineralogical composition of a rock caused by hydrothermal fluids.

argillic: Pertaining to clay or clay minerals; e.g. argillic alteration in which certain minerals of a rock are converted to minerals of the clay group.

break: A general term used in mining geology for any discontinuity in the rock, such as a fault, a fracture, or a small cavity.

caldera: A large, basin-shaped volcanic depression, more or less circular in form, the diameter of which is many times greater than that of the included vent or vents, no matter what the steepness of the walls or form of the floor.

dip: The maximum angle that a structural surface, such as layering in a rock or a fault makes with the horizontal, measured in the vertical plane perpendicular to the strike.

epithermal: Said of a hydrothermal mineral deposit formed within about one kilometre of the Earth’s surface and in the temperature range of 50° to 200° C, occurring mainly as veins.

fault: A fracture or fracture zone along which there has been displacement of the sides relative to one another.

graben: An elongate, relatively depressed crustal unit or block that is bounded by faults on its long sides. It may sometimes be a rift valley.

grade: Relative quantity or percentage of a commodity content in a resource, expressed as grams per tonne or ounces per ton for precious minerals such as gold, or as a weight percentage for other metals.

hydrothermal: Of or pertaining to hot water, to the action of hot water, or to the products of this action, such as a mineral deposit precipitated from a hot aqueous solution, with or without demonstrable association with igneous processes; also said of the solution itself.

hypogene: Said of a geologic process, and of the resultant features, occurring within and below the crust of the Earth.

intrusion: The process of emplacement of magma in pre-existing rock; magmatic activity; also the igneous rock mass so formed within the surrounding rock.

lithology: The description of rocks, especially in hand specimen and in outcrop, on the basis of such characteristics as colour, mineralogic composition, and grain size; the physical character of a rock.

magma: Naturally occurring mobile rock material, generated within the Earth and capable of intrusion and extrusion, from which igneous rocks are thought to have been derived through solidification and related processes.

ore: A naturally occurring material from which a mineral or minerals of economic value can be extracted at a profit under economic conditions that are specified and are generally accepted as reasonable; also the mineral or minerals thus extracted.

phyllite: A general term for minerals with a layered crystal structure; also a metamorphosed rock, intermediate in grade between slate and mica schist.

resource (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 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. Resources are subdivided, in order of increasing geological confidence, into Inferred, Indicated, and Measured categories.

inferred mineral resource: That part of a mineral resource for which quantity and grade or quality can be estimated on the basis of geological evidence and limited sampling and reasonably assumed, but not verified, geological and grade continuity. The estimate is based on limited information and sampling gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes.

indicated mineral resource: That part of a mineral resource for which quantity, grade or quality, 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 the economic viability of the deposit. The estimate is based on detailed and reliable exploration and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes that are spaced closely enough for geological and grade continuity to be reasonably assumed.

measured mineral resource: That part of a mineral resource for which quantity, grade or quality, densities, shape, 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 the economic viability of the deposit. The estimate is based on detailed and reliable exploration, sampling and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes that are spaced closely enough to confirm both geological and grade continuity.

shear: A fracture or fracture zone along which there has been differential movement of the sides relative to one another, typically leading to crushing, brecciation, and subsidiary fractures.

shoot: An elongate pipelike, ribbonlike, or chimneylike mass of ore within a deposit, representing the more valuable part of the deposit.

splay: One of a series of minor faults at the extremities of a major fault; the fault pattern formed by splaying out (the breakup of a fault into a number of minor faults). It is associated with rifts.

structure geomorphology: A comprehensive term for the assemblage of rocks upon which erosive agents are, and have been, at work. The term indicates the product of all constructional agencies, and includes the arrangement and disposition of the rocks, their nature and mode of aggregation, and their initial forms prior to erosion.

structural geology: The general disposition, attitude, arrangement, or relative positions of the rock masses of a region or area; the sum total of the structural features of an area, consequent upon such deformational processes as faulting, folding, and igneous intrusion.

sulphidation (sulfidization; sulphurization) – Reaction between sulfur from an external source and cations (positively charged ions) such as iron, nickel, and copper in solid solution in common rock-forming minerals or in igneous magma, considered as an ore-forming process.

tertiary: The first period of the Cenozoic era (after the Cretaceous of the Mesozoic era and before the Quaternary), thought to have covered the span of time between 65 million and two million years ago. It is divided into five epochs: the Paleocene, Eocene, Oligocene, Miocene, and Pliocene.

trend (geophysical) – That component in a geophysical anomaly map which is relatively smooth, generally produced by regional geologic features (structural geology) – A general term for the direction or bearing of the outcrop of a geologic feature of any dimension, such as a layer, vein, ore body, fold, or orogenic belt.