Mining-Prospecting Dictionary

• Face: The surface of a working area that is to be mined.
• Face Value: The nominal value given to legal tender coin or currency (i.e., a 1-ounce gold American Eagle has a face value of $50).
• Fahrenheit: A system of temperature measurement.
• False set: Temporary timbering in a mine.
• Fault: A fracture or fissure in the earth's surface.
• Fault Gouge: Soft, uncemented pulverized clay or claylike material, commonly a mixture of minerals in finely divided form, found along some faults or between the walls of a fault, and filling or partly filling a fault zone; a slippery mud that coats the fault surface or cements the fault breccia. It is formed by the crushing and grinding of rock material as the fault developed, as well as by subsequent decomposition and alteration caused by underground circulating solutions.
• Fault Zone: A fault that is expressed as a zone of numerous small fractures or of breccia or fault gouge. A fault zone may be as wide as hundreds of meters.
• Feasibility Studies: Determinations of the economic feasibility of mining a deposit, based on progressively greater levels of information.
• Fill; Man-made deposits of natural earth materials (e.g. rock, soil, gravel) and waste materials (e.g. tailings or spoil from dredging), used to fill an enclosed space such as an old stope or chamber in a mine.
• Fine gold: Pure gold of 1000 fine. Also very small gold particles.
• Fineness: In precious metals, the quantity of pure gold, platinum, etc., contained in 1,000 parts of an alloy. Gold bullion of .995 fineness contains 995 parts gold and 5 parts of another metal(s).
• Fire assay: The assaying of metallic minerals by use of a miniature smelting procedure with various fluxing agents.
• Fissile: Capable of being split or removed in sheets, as slate and mica.
• Fissure: An opening or crack in rock formations, even if filled with rock.
• Flask: Unit and container for measuring mercury, equal to 76 pounds.
• Float: Rocks that have broken off an ore deposit and moved down-slope.
• Floor: The bottom of a mining level in underground mines.
• Flotation: An ore milling process for concentrating minerals based on the selective adhesion of certain minerals to air bubbles in a mixture of water and ground-up ore. When the right chemicals are added to a frothy water bath of ore that has been ground to the consistency of talcum powder, the minerals will float to the surface. The metal-rich flotation concentrate is then skimmed off the surface.
• Flour: Extremely fine gold particles; also finely-ground ore.
• Flume: A trough used to convey water.
• Fluvial: Sand and gravel laid down by water movement.
• Flux: Chemical or compound added to crushed ore to aid in its reduction by heat, as in fire assaying.
• Fold : A bending in a rock structure.
• Foliated: Leaf-like formations of minerals.
• Fools gold: Substances resembling gold in color, like pyrite and mica.
• Footwall: The rock underlying an ore deposit. The wall or the rock on the underside of a vein or ore deposit
• Formation: Denotes a particular rock structure; also the processes by which a mineral deposit is formed.
• Forward Contract: A cash rather than a futures transaction in which the buyer and seller agree upon delivery of a specified quality and quantity of metal at a specified future date.
• Fossil: Impressions of plants or animals in rocks.
• Four Nines: Gold with a fineness of .9999 - the purest gold available.
• Fracture: A break in a rock formation; surface of a broken rock.
• Fumarole: A site where fumes are expelled in a volcanic area
• Furnace: Equipment for roasting or smelting ores.
• Fusion: The melting of a substance.
• Futures Contract: A firm commitment to make or accept delivery of a specified quantity and quality of a commodity during a specific month in the future.
• Futures Commission Merchant: An individual or organization which solicits or accepts orders to buy or sell futures contracts or commodity options, and accepts money or other assets from customers in connection with such orders.