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Liberty Star - Minerals glossary Category: Agriculture and Industry > Minerals terms Date & country: 10/11/2016, USA Words: 619

Mafic
Igneous rocks composed mostly of dark, iron- and magnesium-rich minerals.

Magma
The molten material deep in the Earth from which rocks are formed.

Magmatic segregation
An ore-forming process whereby valuable minerals are concentrated by settling out of a cooling magma.

London Metals Exchange
A major bidding market for base metals, which operates daily in London.

Long position
Securities owned outright or carried on margin.

Lode
A mineral deposit in solid rock.

Logging
The process of recording geological observations of drill core either on paper or on computer disk.

London fix
The twice-daily bidding session held by five dealing companies to set the gold price. There are also daily London fixes to set the prices of other precious metals.

Lignite
A soft, low-rank, brownish-black coal.

Limestone
A bedded, sedimentary deposit consisting chiefly of calcium carbonate.

Limit order
An order made by a client to a broker to buy or sell shares at a specified price or better.

Limonite
A brown, hydrous iron oxide.

Line cutting
Straight clearings through the bush to permit sightings for geophysical and other surveys.

Lithology
(a) The description of rocks, esp. sedimentary clastics are esp. in hand specimen and in outcrop, on the basis of such characteristics as color, structures, mineralogic composition, and grain size. As originally used, `Lithology` was essentially synonymous with petrography as currently defined. (b) The physical character of a rock. —Adj: lithologic. Cf: petrology.

Level
The horizontal openings on a working horizon in a mine; it is customary to work mines from a shaft, establishing levels at regular intervals, generally about 50 meters or more apart.

Leachable
Extractable by chemical solvents.

Leaching
A chemical process for the extraction of valuable minerals from ore; also, a natural process by which ground waters dissolve minerals, thus leaving the rock with a smaller proportion of some of the minerals than it contained originally.

Lens
Generally used to describe a body of ore that is thick in the middle and tapers towards the ends.

Lenticular
A deposit having roughly the form of a double convex lens.

Lava
A general name for the molten rock ejected by volcanoes.

Lagging
Planks or small timbers placed between steel ribs along the roof of a stope or drift to prevent rocks from falling, rather than to support the main weight of the overlying rocks.

Lamprophyre
An igneous rock composed of dark minerals that occurs in dykes; sometimes contains diamonds.

Laterite
A residual soil found in tropical countries out of which the silica has been leached. May form ore bodies of iron, nickel, bauxite and manganese.

Launder
A chute or trough for conveying pulp, water or powdered ore in a mill.

Jaw crusher
A machine in which rock is broken by the action of steel plates.

Jig
A piece of milling equipment used to concentrate ore on a screen submerged in water, either by the reciprocating motion of the screen or by the pulsation of water through it.

Kimberlite
A variety of peridotite; the most common host rock of diamonds.

Intrusive Breccia
A rock in which angular fragments are surrounded by a mass of fine-grained minerals.

Ion exchange
An exchange of ions in a crystal with ions in a solution. Used as a method for recovering valuable metals, such as uranium, from solution.

IP
Induced polarization. A method of ground geophysical surveying employing an electrical current to determine indications of mineralization.

Iron Oxide Copper-Gold (IOCG) Uranium Deposits
The IOCG deposit is a complex type of system that is often mined for copper and gold but can also contain a significant amount of uranium. This type of deposit is typified by its main example, the world’s largest uranium deposit, Olympic Dam. Olympic Dam contains approximately 1 billion pounds of U308 in reserve and produced more than 9% of the world’s uranium in 2004. The Olympic Dam deposit formed when hot mineral- rich fluids from a deep source penetrated a higher granite host rock to cause brecciation and mineral deposition. Olympic Dam is localized at the intersection of major structures and has an associated magnetic and gravity anomaly. Mineralization includes copper, uranium, gold, silver, light rare earth elements and iron oxides. The age of the Olympic Dam host rocks and deposit are the same and are comparable to the ages of the Central Mineral Belt uranium district.

Initial public offering
The first sale of shares to the public, usually by subscription from a group of investment dealers.

Institutional investors
Pension funds and mutual funds, managing money for a large number of individual investors.

Intermediate rock
An igneous rock containing 52% to 66% quartz.

Intrusive
A body of igneous rock formed by the consolidation of magma intruded into other rocks, in contrast to lavas, which are extruded upon the surface.

Inferred Mineral Resource
An Inferred Mineral Resource is 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.

Induced polarization
see IP

Industrial minerals
Non-metallic, non-fuel minerals used in the chemical and manufacturing industries. Examples are asbestos, gypsum, salt, graphite, mica, gravel, building stone and talc.

Hydrothermal
Relating to hot fluids circulating in the Earth’s crust.

Igneous rocks
Rocks formed by the solidification of molten material from far below the Earth’s surface.

Ilmenite
An ore mineral of titanium, being an iron-titanium oxide.

In Situ Leaching mining
(ISL) The recovery, by chemical leaching, of the valuable components of an orebody without physical extraction of the ore from the ground. Also referred to as `solution mining.`

Indicated Mineral Resource
An Indicated Mineral Resource is 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.

Hydrometallurgy
The treatment of ore by wet processes (e.g., leaching) resulting in the solution of a metal and its subsequent recovery.

Hydraulic filling
A variation of cut and fill stoping which involves returning carefully sized mill tailings in a slurry to the stopes underground, where the slurry is hosed into place as stope fill under the pressure developed by the head. Water quickly drains from the tailings fill, which becomes compact enough to support the weight of men and equipment as they continue to stope overhead. Hydraulic filling is a convenient way of combining the solutions to the stope fill and mill tailings disposal problems.

Host rock
The rock surrounding an ore deposit.

Hoist
The machine used for raising and lowering the cage or other conveyance in a shaft.

Holding company
A corporation engaged principally in holding a controlling interest in one or more other companies.

Hornfels
A fine-grained contact metamorphic rock.

Horse
A mass of waste rock lying within a vein or orebody.

Horst
An upfaulted block of rock.

Highly enriched uranium
(HEU) Any form of uranium with a U-235 concentration of 20% or higher.

High-grader
One who steals rich ore, especially gold, from a mine.

High grade
Rich ore. As a verb, it refers to selective mining of the best ore in a deposit.

Heap leaching
A process whereby valuable metals (usually gold and silver) are leached from a heap, or pad, of crushed ore by leaching solutions percolating down through the heap and are collected from a sloping, impermeable liner below the pad.

Hedging
Taking a buy or sell position in a futures market opposite to a position held in the cash market to minimize the risk of financial loss from an adverse price change.

Hematite
An oxide of iron, and one of that metal’s most common ore minerals.

Halite
Rock salt.

Hanging wall
The rock on the upper side of a vein or ore deposit.

Head grade
The average grade of ore fed into a mill.

Heap leach solutions
The separation, or dissolving-out, from mined rock of the soluble uranium constituents by the natural action of percolating a prepared chemical solution through mounded (heaped) rock material. The mounded material usually contains low grade mineralized material and/or waste rock produced from open pit or underground mines. The solutions are collected after percolation is completed and processed to recover the valued components.

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

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

Gypsum
A sedimentary rock consisting of hydrated calcium sulfate.

Gyratory crusher
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.

Grouting
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.

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

Greenfield Project
In many disciplines a greenfield is a project that lacks any constraints imposed by prior work. The analogy is to that of construction on greenfield land where there is no need to work within the constrains of existing buildings or infrastructure. In mining, land that has yet to be fully explored.

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

Grizzly
(or mantle) 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.

Gross value
The theoretical value of ore determined simply by applying the assay of metal or metals and the current market price. It must be used only with caution and severe qualification.

Gravity meter, gravimeter
An instrument for measuring the gravitational attraction of the Earth; gravitational attraction varies with the density of the rocks in the vicinity.

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

Graben
A down faulted block of rock.

Grab sample
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.

Gold
A precious yellow metallic element, highly malleable and ductile, and not subject to oxidation or corrosion. Symbol: Au; atomic weight: 196.967; atomic number: 79; specific gravity: 19.3 at 20°C.

Gold loan
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.

Gossan
The rust-colored capping or staining of a mineral deposit, generally formed by the oxidation or alteration of iron sulfides.

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

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

Geothermal
Pertains to the heat of the Earth’s interior.

Glacial drift
Sedimentary material that has been transported by glaciers.

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

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

Geoscientific
Pertaining to the earth sciences and sciences specific to mineral exploration such as geology, geochemistry, geophysics, hydrology, etc.

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

Geomorphic
Pertaining to the form of the Earth or of its surface features: e.g. a geomorphic province.

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

Geophysics
The study of the physical properties of rocks and minerals.

Gabbro
A dark, coarse-grained igneous rock.

Galena
Lead sulfide, the most common ore mineral of lead.

Gamma
A unit of measurement of magnetic intensity.

Gangue
The worthless minerals in an ore deposit.

Geiger counter
An instrument used to measure radioactivity (e.g., that which emanates from certain minerals) by means of a Geiger-Mueller tube.

Geochemistry
The study of the chemical properties of rocks.

Free milling
Ores of gold or silver from which the precious metals can be recovered by concentrating methods without resort to pressure leaching or other chemical treatment.

Fracture
A break in the rock, the opening of which allows mineral-bearing solutions to enter. A `cross-fracture` is a minor break extending at more-or-less right angles to the direction of the principal fractures.

Foreign sale
A uranium sale to a firm located outside the United States.

Forward contract
The sale or purchase of a commodity for delivery at a specified future date.

Forward costs
(uranium) The operating and capital costs that will be incurred in any future production of uranium from in-place reserves. Included are costs for labor, materials, power and fuel, royalties, payroll taxes, insurance, and general and administrative costs that are dependent upon the quantity of production and, thus, applicable as variable costs of production. Excluded from forward costs are prior expenditures, if any, incurred for property acquisition, exploration, mine development, and mill construction, as well as income taxes, profit, and the cost of money. Note: By use of forward costing, estimates of reserves for ore deposits in differing geological settings can be aggregated and reported as the maximum amount that can theoretically be extracted to recover the specified costs of uranium oxide production under the listed forward cost categories.