A dark, coarse-grained igneous rock.

Lead sulfide, the most common ore mineral of lead.

A horizontal or a nearly horizontal underground passage, either natural or artificial.

A unit of measurement of magnetic intensity.

The worthless rock in a vein which holds valuable metals.

An instrument used to measure the radioactivity that emanates from certain minerals by means of a Geiger-Mueller tube.

The study of the chemical properties of rocks.

One who studies the constitution, structure, and history of the earth's crust, conducting research into the formation and dissolution of rock layers, analyzing fossil and mineral content of layers, and endeavoring to fix historical sequence of development by relating characteristics to known geological influences (historical geology).

The science concerned with the study of the rocks which compose the Earth.

A scientific method of prospecting that measures the physical properties of rock formations. Common properties investigated include magnetism, specific gravity, electrical conductivity and radioactivity.

The study of the physical properties of rocks and minerals.

Pertains to the heat of the Earth's interior.

Sedimentary material that has been transported by glaciers.

Lines or scratches on a smooth rock surface caused by glacial abrasion.

An open pit from which ore is extracted, especially where broken ore is passed to underground workings before being hoisted.

A layered or banded crystalline metamorphic rock, the grains of which are aligned or elongated into a roughly parallel arrangement.

A form of debt financing whereby a potential gold producer borrows gold from a lending institution, sells the gold on the open market, uses the cash for mine development, then pays back the gold from actual mine production.

Gold particles found within material deposited by a glacier. Gold-in-till is formed when a glacier overrides a gold-bearing deposit, eroding gold and entraining it into the ice. When the glacier melts, the gold is laid down along with sand, silt, clay, and other material to form a deposit known as a till. Gold-in-till sampling is sometimes used to determine the general location of a gold-bearing ore body.

An area of rusty staining on the rocks that is formed when sulphide minerals are oxidized. Often an important indicator to geologists that minerals of interest may be present. Iron most usually leaves the rusty stains, nickel a light green, and secondary uranium minerals can leave an orangish stain.

Fine, putty-like material composed of ground-up rock found along a fault.

A sample from a rock outcrop that is assayed to determine if valuable elements are contained in the rock. Literally walking the ground and grabbing prospective looking rock samples, mapping the location of each. The samples are then assayed to begin forming a map of where further investigation may be warranted. A grab sample is not intended to be representative of the deposit, and usually the best-looking material is selected.

A downfaulted block of rock.

In petrology, that factor of the texture of a rock composed of distinct particles or crystals which depends upon their absolute size.

A coarse-grained intrusive igneous rock consisting of quartz, feldspar and mica.

An instrument for measuring the gravitational attraction of the earth; gravitational attraction varies with the density of the rocks in the vicinity.

Recovery of gold from crushed rock or gravel using gold's high specific gravity to separate it from lighter material

An area underlain by metamorphosed volcanic and sedimentary rocks, usually in a continental shield.

Material used to finely grind ore material to a size which allows recovery of the desired contained material

A grating, usually constructed of steel rails, placed over the top of a chute or ore pass for the purpose of stopping large pieces of rock or ore that may hang up in the pass.

The total number of acres that a company holds on a project. This term is in contrast to net acres, the number of acres the company actually owns, given its ownership percentage of the property.

The theoretical value of ore determined simply by multiplying the assay of metal or metals and the current market price. It must be used only with caution and severe qualification because gross value completely ignores all the costs that have to go into extracting and processing the metals, including the time value of money. Also, transporting the ore, smelting costs - including dealing with any negative by products (mercury or arsenic), etc.

A share of gross revenue from the sale of minerals from a mine.

The regulation and final arresting of the closure of the walls of a mined area. The term generally refers to measures taken to prevent roof falls or coal bursts.

The pressure to which a rock formation is subjected by the weight of the superimposed rock and rock material or by diastrophic forces created by movements in the rocks forming the earth's crust. Such pressures may be great enough to cause rocks having a low compressional strength to deform and be squeezed into and close a borehole or other underground opening not adequately strengthened by an artificial support, such as casing or timber.

The process of sealing off a water flow in rocks by forcing a thin slurry of cement or other chemicals into the crevices; usually done through a diamond drill hole.

Finances or supplies of food, etc., furnished to a prospector in return for an interest in any discoveries made.

The timber rails installed along the walls of a shaft for steadying, or guiding, the cage or conveyance.

A cement applied by spraying to the roof and sides of a mine passage.

A sedimentary rock consisting of hydrated calcium sulfate.

A machine that crushes ore between an eccentrically mounted crushing cone and a fixed crushing throat. Typically has a higher capacity than a jaw crusher.