Glossary

A

adit. (a) A horizontal or nearly horizontal passage driven from the surface or portal for the working or unwatering of a mine. If driven through the hill or mountain to the surface on the opposite side it would be a tunnel. Also called drift; adit level. (b) A passage driven into a mine from the side of a hill.

alluvial ore deposit. An ore deposit in which the valuable mineraI particles have been transported and deposited by a stream.

alluvial tin. Stream tin, or cassiterite pebbles in the gravel along the courses of valleys and rivers on the bedrock.

alluvium. Clay silt, sand, gravel, or other rock materials transported by flowing water and deposited in comparatively recent geologic time as sorted or semisorted sediments in riverbeds, estuaries, and flood plains, on lakes, shores, and in fans at the base of mountain slopes, and estuaries.

B

basic hornfels. A hornfels derived from a basic igneous rock.

basic lavas. The lavas poor in silica, less than 52 percent. The rocks are typically dark in colour and heavy, and are well represented by the familiar-type basalt/rocks.

basic magmas. Those rich in iron, magnesium and calcium.

basic rock. A term rather loosely used in lithology generally meaning one of the following: (1) an igneous rock containing less than 55 percent of silica, free or combined; (2) an igneous rock in which minerals comparatively low in silica and rich in the metallic bases, such as the amphiboles, the pyroxenes, biotite and olivine are dominant; or (3) an igneous rock composed chiefly of dark-coloured minerals.

blue elvan. A basaltic rock or greenstone renowned for its hardness.

C

crop out. Synonym for outcrop.

cross course. A vein or lode, which intersects the main productive veins or lodes. Sometimes known as crossvein or crosslode.

crosscut tunnel. A tunnel driven at approximately right angles to a main tunnel, or from the bottom of a shaft or other opening, across the formation to an objective point, The term “crosscut” would seem more appropriate as the term tunnel implies being open to ‘the surface at both ends, as a railroad tunnel.

D

Drift. A tunnel, normally from surface, following a vein or seam, either horizontally or inclined.

Dike (Dyke). A cross cutting intrusion of rock.

E

elvan. A quartz porphyry, chemically similar to granite.

elvan course. A plutonic dike; an elvan dike.

F

Fault. Normally planar fracture in rocks where the rocks one side have moved relative to the other side.

G

gneiss. A metamorphic rock of coarse grain size, characterized by a mineral banding, in which the light minerals (quartz and feldspar) are separated from the dark ones (mica and/or hornblende). The layers of dark minerals are foliated, while the light bands are granulitic.

gneissic; gneissoid. Having the appearance or character of gneiss.

gneissic quarizite. A metamorphic rock intermediate between gneiss and quartzite.

gneissose. (a) Resembling gneiss. (b) Having composite structure of alternating schistose and granulose bands and lenses which differ in mineral composition and texture.

gneissose granite. A general term for granitic rocks with gneissose structure, due, not to rnetamorphism, but to the constrained movements of a viscous magma during crystallization.

gneissose structure. A composite structure due to the alternation of schistose and granulose bands and lenticles, which are dissimilar both in mineral composition and in texture. The foliation is interrupted; and while a gneiss may split along a plane of schistosity, it does so less readily than a schist, and exposes a much rougher fracture surface. There can be all transitions between schistose, granulose, and gneissose structure.

goffan; goffen. (a) A surface working in which the material is thrown from one platform to another. (b) A long narrow surface working.

grain size. (a) A term relating to the size of mineral particles that make up a rock or sediment. (b) For metals, a measure of the areas or volumes of grains in a polycrystalline material, usually expressed as an average when the individual sizes are fairly uniform. Grain sizes are reported in terms of number of grains per unit area or volume, average diameter, or as a grain-size number derived from area measurements. (c) The size or size distribution of refractory particles determined usually by sieve analysis.

graniform. Formed like a grain; composed of grains or granules.

granite. (a) A coarse-grained igneous rock containing megascopic quartz, averaging 25 percent, much feldspar (orthoclase, microcline, sodic plagioclase), and mica or other coloured minerals. In a wide sense, granite includes alkali granites, adamellites, and granodiorites, while the granite clan includes the medium- and fine grained equivalents of these rock types. Because of its extreme hardness, granite is used largely for heavy engineering, building works and road metalling. (b) A light-coloured crystalline rock composed chiefly of quartz and feldspar; generally produces a light-colored soil; called by some drillers white granite and by others sand rock. (c) Loosely used for any light-coloured, coarse-grained igneous rock.

granite aplite. A dike rock composed almost entirely of light-coloured minerals and having a characteristic fine-grained granitic texture. Aplites may range in composition from granitic to gabbroic, but when the term is used without a modifier, it is generally understood to be granitic, that is, consisting essentially of quartz and orthoclase.

granite gneiss. (a) A coarsely crystalline, banded metamorphic rock of granitic composition. (b) A primary igneous gneiss of granitic composition.

granite porphyry. Practically, a quartz porphyry with a coarsely crystalline ground mass and preponderating phenocrysts. The chief phenocrysts are, however, feidspar.

granite wash. The material eroded from out-crops of granites, syenites, diorites, granodiorites, monzonites and their fine-grained or aphanitic equivalents and re-deposited, forming a rock having approximately the same major mineral constituents as the original rock.

granitic. Characteristic of, composed of, pertaining to, or resembling granite.

granitic rock. A name generally applied to rocks resembling granite in appearance and composition, but also (not recommended) to mafic or even ultramafìc rocks.

greenland spar. cryolite.

green lead ore. pyromorphite.

green marble. A commercial term for serpentine.

green mineral. Same as green carbonate of copper; malachite.

green quartz. A name sometimes used for green transparent fluorite.

green rock. Basalt.

green roof. A miner’s term for a roof which has not broken down or shows no sign of taking weight.

greensand. (a) A sedimentary deposit that consists largely of dark greenish grains of glauconite often mingled with clay or sand, occurs abundantly in the Cretaceous often little or not at all cemented, and is used as a water softener and as a source of potash. (b) A highly siliceous sand that contains a little magnesia and alumina mixed with about one-twelfth of its bulk of powdered coal or charcoal and is used when dampened for making foundry molds.

greensand beds. In general, any beds of Cretaceous or Tertiary containing a green iron-potassium silicate; specifically, the Lower Cretaceous of England, whether containing the green silicate or not.

greensand marl. Sand or marl containing glauconite.

greenschist. A metamorphosed basic igneous rock which owes its colour and schistosity to abundant chlorite. See also basic schist; cucalite; epidiorite; greenstone; ophiolite; ophite; prasinite.

greenstone. (a) An old field name for those compact, igneous rocks that have developed enough chlorite in alteration to give them a green colour. They are mostly dia-bases and diorites. It is often used as a prefix to other rock names. The term is used frequently when no accurate determination is possible. (b) Includes rocks that have been metamorphosed or otherwise so altered that they have assumed a distinctive greenish colour owing to the presence of one or more of the following minerals chlorite, epidote, or actinolite.

greet. Sand and grit.

greet stone. (a) Coarse or gritty sandstone, Yorkshire coalfield. (b) Soft beds of the Lincolnshire limestone.

greisen. (a) A granitoid but often cellular rock composed of quartz and muscovite or some related mica, rich in fluorine. It is the characteristic mother rock of the ore of tin, cassiterite, and is, in most cases, a result of the contact action of granite and its evolved mineralizers. (b) A pneumatolytically altered granitic rock composed largely of quartz, mica, and topaz. The mica is usually muscovite or lithium mica, and tourmaline, fluorite, rutile, cassiterite, and wolframite are common accessories. (c) A coarse grained, tin-bearing rock containing muscovite, quartz, topaz, or tourmaline.

greisenization. The process by which other rocks are converted into greisen.

H

Head. Soil and rock debris moved downslope by water saturation and gravity.

Hornfels. Massive, finess grained contact metamorphosed rock.

I

Incline shaft. A shaft sunk at an inclination from the vertical usually following the dip of a lode.

Intrusion. In geology, a mass of igneous rock which, while molten, was forced into or between other rocks.

intrusive rock. A rock that consolidated from magma beneath the surface of the earth.

K

killas. (a) Miner’s term for the slates or schists that form the country rock of the Cornish tin veins. (b) Term used in the china-clay mines for the altered schistose or hornsfelsic rocks in contact with the granite and often considerably modified by emanations from the later.

L

level. A main underground roadway or passage driven along the level course to afford access to the stopes or workings and to provide ventiltion and haulageways for the removal of coal or ore.

level crosscut. A horizontal crosscut.

lode. Strictly a fissure in the country rock filled with mineral; usually applied to metalliferous lodes. In general miners’ usage, a lode, vein, or ledge is a tabular deposit of valuable mineral between definite boundaries. Lode, as used by miners, is nearly synonymous with the term vein, as employed by geologists.

M

mafic. Pertaining to or composed dominantly of the ferromagnesian rock-forming silicates.

metamorphosed. Rocks altered by either heat or pressure; or both.

O

open workings. Surface workings, for exampIe, a quarry or opencast mine. Among the minerals often exploited by open workings are coal, brown coal, gems, and the ores of copper, gold, iron, lead, and tin and all kinds of stone. Also called open work.

R

raise. (a) A vertical or inclined opening drive upward from a level to connect with the level above, or to explore the ground for a limited distance above one level. After two levels are connected, the connection may be a winze or a raise, depending upon which level is taken as the point of reference. (b) A mine opening, like a shaft, driven upward from the back of a level to a level above, or to the surface. (c) To cause to rise, or expand upward. (d) To windcoal, etc., to the surface. (e) To take up the floor or bottom rock in a room, gangway, or entry to increase the height for haulage. (f) A vertical or inclined opening or passageway driven to connect one mine working place with another at a higher level. Also called rise; riser.

S

serpentine rock. A rock generally having a dull green color and often spotted or mottled, resembling the spots of a serpent’s skin.

shadd. (a) Smooth, round stones on the surface, containing tin ore, and indicating a vein. (b) Same as shoad.

shaft. (a) An excavation of limited area compared with its depth, made for finding or mining ore or coal, raising water, ore, rock, or coal, hoisting and lowering men and material, or ventilating underground workings. The term is often specifically applied to approximately vertical shafts, as distinguished from an incline or inclined shaft. A shaft is provided with a hoisting engine at the top for handling men, rock, and supplies, or it may be used only in connection with pumping or ventilating operations (b) A wooden handle of a pick, etc. (c) The term shaft came into use towards the end of the sixteenth century. It means a vertical or steeply inclined excavation or opening from the surface (usually) down through the strata to the coal or mineral to bedeveloped. A mine is provided with an upcast and a downcast shaft. A shaft in metal mining may be sunk upon a vein, even if the inclination is but slight.

shaft bottom. Pit bottom.

shaft collar. (a) In a mine shaft, the first wood frame of the shaft; sometimes used in reference to the mouth or portal of the tunnel. (b) Supporting framework at top of shaft from which linings may be hung. (c) The term applied to the timbering or concrete around the mouth or top of a shaft. (d) The bar, or crosspiece, in a framed timber set. (e) The junction of a mine shaft and the surface. (f) The beginning point of a shaft or drill hole, the surface. (g) The mouth of the mine shaft.

shaft foot. The bottom of a shaft.

shaft house. A building at the mouth of a shaft, where ore or rock is received from the mine.

shaft lining. The timber, steel, brick, or concrete structure fixed around a shaft to support the walls. In modern shafts, a concrete lining is generally favoured as a permanent shaft support.

shaftman. In mining, one who inspects shaft timbering, guides, guards, and parts from top of slowly moving cage or by climbing down manway, replacing and repairing damaged or defective shaft timbers, cage guides and guards, and other parts; and tightening joints of compressed air, steam, and water pipes. Also called shaft mechanic; shaft repairman; shaft tender; sheaveman.

stope. (a) An excavation from which ore has been excavated in a series of steps. A variation of step. Usually applied to highly inclined or vertical veins. Frequently used incorrectly as a synonym for room, which is a wide working place in a flat mine. (b) To excavate ore in a vein by driving horizontally upon it a series of workings, one immediately over the other, or vice versa. Each horizontal working is called a stope because when a number of them are in progress, each working face under attack assumes the shape of a flight of stairs. When the first stope is begun at a lower corner of the body of ore to be removed, and, after it has advanced a convenient distance, the next is commenced above it. This is called overhand stoping. When the first stope begins at an upper corner, and the succeeding ones are below it, it is called underhand stoping. The term stoping is loosely applied to any subterranean extraction of ore except that which is incidentally performed in sinking shafts, driving levels, etc,, for the purpose of opening the mine. (c) Commonly applied to the extraction of ore, but does not include the ore removed in sinking shafts and in driving levels, drifts and other development openings. (d) The working above and below a level where the mass of the ore body is broken. A stope is the very antithesis of a shaft, tunnel, drift, winze, or other similar excavation in a mine. (e) Any excavation in a mine, other than development workings, made for the purpose of extracting ore. The outlines of the ore body determine the outlines of the stope. The term is also applied to breaking ground by drilling and blasting or other methods. (f) The opening created when ore is mined. As a rule sloping is started on each side of a raise-winze connection. (g) A body of mineral left by running drifts about it. Workings in a mine, or the activity by which ore is broken from blocks in ore reserves and other areas. A cavern, chamber, or room from which ore has been extracted.

stope development. The driving of subsidiary openings designed to prepare blocks of ore for actual extraction by stoping.

stoping. The act of excavating ore, either above or below a level, in a series of steps. In its broadest sense stoping means the act of excavating ore by means of a series of horizontal, vertical, or inclined workings in veins or large, irregular bodies of ore, or by rooms in flat deposits. It covers the breaking and removal of the ore from underground openings, except those driven for exploration and development. 

stoping width. (a) Width of lode broken during mining, including any barren rock. (b) Used in underground sampling and is estimated from direct measurement behind the stope face, and reduced to allow for any waste stowed. With wide tabular deposits, there is little difference between the stoping width and the clean width.

W

Whim. A large capstan or vertical drum turned by horsepower or steampower for raising coal, or water, etc., from a mine.

whim shaft. A shaft through which coal, ore, water, etc., are raised froth a mine by means of a whim.

If you have any questions related to Mining Searches, our Reports or Investigations please contact us. Our advisors are ready and happy to take your call on: 01209 218861 or use our contact form.