Logo Picture Left SideLogo Picture Right SideLogo Text at Center
Home > Search > Site Map > Quarries - Economics, Methods, Stone Types... > Glossary of Scientific and Quarry Terms

Glossary of Scientific and Quarry Terms

The following terms are quoted from The Chief Commercial Granites of Massachusetts, New Hampshire and Rhode Island, Bulletin 354 (1908) and The Commercial Granites of New England, Bulletin 738, both by T. Nelson Dale.

Accessory Minerals Accessory minerals in granite are original constituents of the rock, found only in small, often only in microscopic quantity.
Acidic A term applied to rocks in which silicic acid (silica) or quartz predominates.
Allanite An opaque black mineral (silicate), brown in thin section, one of the primary less common accessory constituents of granite, which contains from 12 to 17 elements, including 6 of the rarer ones.
Anticline A term applied to granite sheets or sedimentary beds that form an arch.
Aplite Fine-grained granite, usually occurring in dikes and containing little mica and a high percentage of silica.
Basic A term applied to rocks in which the iron-magnesia minerals and feldspars with lime and soda predominate, such as diabase or basalts.
Black Horse Term used by quarrymen in Rhode Island to denote a dark biotite gneiss in contact with the granite.
Blind Seams Quarrymen's term for incipient joints.
Bowlder Quarry One in which the joints are either so close or so irregular that no very large blocks of stone can be quarried.
Channel A narrow artificial incision across a mass of rock, which, in the case of a granite sheet, is made either by a series of contiguous drill holes or by blasting a series of holes arranged in zigzag order.
Cleavage Cleavage, when applied to a mineral, designates a structure consequent upon the geometrical arrangement of its molecules at the time of its crystallization.
Close Jointed A term applied to joints that are very near together.
Crocus A term used in the Milford, N. H., quarries to denote gneiss or any other rock in contact with granite.
Crush-Border A microscopic granular structure sometimes characterizing adjacent feldspar particles in granite in consequence of their having been crushed together during or subsequent to their crystallization.
Cut-off Quarrymen's term for the direction along which the granite must be channeled, because it will not split. Same as "hardway."
Dendrites Plantlike crystallization of iron or manganese oxides on the surfaces of fissures in any rock or mineral. Frost crystals on window panes are of like character.
Dike A mass of granite, diabase, basalt, or other rock which has been erupted through a narrow fissure.
Dimension Stone A term applied to stones that are quarried of required dimensions.
Dip The inclination from the horizon, given in terms of degrees, of a sheet, joint, heading, dike, or other structural plane in a rock.
Drift Sand and bowlders deposited by the continental glacier.
Drumlin Oval hillock of clay and bowlders formed beneath the ice sheet of the glacial epoch.
Erosion The wearing away of portions of a rock by such natural agencies as stream or ice action.
Exfoliation The peeling of a rock surface in sheets owing to changes of temperature or other causes.
Faulting The slippage of a rock mass or masses along a natural fracture.
Flow-Structure The parallel arrangement of the minerals in granite or other igneous rock in the direction of its flowage during its intrusion.
Geode A rock cavity lined with crystals. Geodes in granite are attributed to steam or gas bubbles.
Grain Grain in granite is practically the direction in which the stone splits "next easiest," the "rift" being that in which it splits most readily.
Grout A term applied to the waste material of all sizes obtained in quarrying stone.
Grow-on Quarrymen's term to designate the place where the sheet structure dies out, or the place where two sheets appear to grow onto one another.
Hard-way The direction at right angles to both rift and grain in which granite does not split readily. (See Cut-off.)
Heading A collection of close joints.
Heading-seam See Joint.
Hematite An oxide of iron.which when scratched or powdered gives a cherry-red color.
Igneous A term applied to rocks that have originated in a molten condition.
Joints More or less steeply inclined fractures which cross the granite sheets and which are attributed to various stresses.
Kaolin A hydrous silicate of alumina derived from the alteration of feldspar.
Kaolinization The process by which a feldspar passes into kaolin.
Knots A term applied by quarrymen to dark gray or black objects, more or less oval or circular in cross-section, which are segregations of black mica or hornblende formed in the granite while in a molten state. English quarrymen call them "heathen."
Knox Hole A circular drill with two opposite vertical grooves which direct the explosive power of the blast.
Lewis Hole An opening made by drilling two or three holes near together and chiseling out the intervening rock.
Limonite A hydrous oxide of iron.;a hydrated hematite, which, when scratched or powdered, gives a brownish rust color.
Matrix The general mass of a rock which has isolated crystals; sometimes called groundmass.
Metamorphism The process, partly physical, partly chemical, by which a rock is altered in the molecular structure of its constituent minerals and in their arrangement. Metamorphism may be regional, due to crustal compression, or contact, due to the intrusion of sedimentary rock by an igneous rock.
Millimeter French decimal lineal measure, the thousandth part of a meter or the tenth part of a centimeter. It is equivalent to nearly 0.04 inches, the meter being 10/27 inches.
Monolith A column or monument of one stone.
Motion A term used in granite regions to designate small paving-block quarries.
Ophitic A term applied to microscopic rock texture to designate a mass of longish interlacing crystals, the spaces between which have been filled with minerals of later crystallization.
Oreď A term applied to microscopic rock texture to designate a mass of longish interlacing crystals, the spaces between which have been filled with minerals of later crystallization.
Pegmatite A very coarse granite occurring in irregular dikes or lenses in granites and some other rocks.
Phenocryst A term applied to isolated crystals visible to the unaided eye and lying in the mass of a rock of igneous origin.
Plagioclase A term applied to all those feldspars that are not potash feldspars.
Plug and Feathers A quarrymen's term. The plug is a wedge, and the feathers are two short pieces of half-round iron whose curved sides fit the drill hole while their flat sides receive the plug. By driving the plugs in a series of holes a stone may be broken.
Polarized Light Light whose vibrations, unlike those of ordinary light, which are in all directions, are in only one plane. Polarized light is used in the microscopic study of rocks.
Porphyritic A term applied to rock texture to designate the presence of isolated crystals in a general mass (matrix or groundmass) of finer material.
Pseudomorph Signifies false form, and designates a crystal in which, owing to various chemical changes, the original mineral has been more or less replaced by others. The form of the crystal no longer corresponds to the mineral.
Quartz Monzonite Technical designation for a granite in which the percentages of soda-lime and of potash feldspar are nearly the same or in which the former exceeds the latter. In ordinary granites the amount of soda-lime feldspar is relatively small.
Random Stone A term applied by quarrymen to quarried block of any dimensions. (See definition of dimension stone.)
Rift A quarrymen's term to designate an obscure microscopic cleavage in granite which greatly facilitates quarrying.
Run A term used by quarrymen in connection with "rift," apparently to denote the course of the deflection of the rift due to gravity, strain, or other not yet understood cause.
Salt-Horse Quarrymen's term for aplite.
Sand Seams Quarry term for more or less minute veins or dikes of muscovite (white mica) with some quartz, in cases also with feldspar.
Sand Streaks Same as sand seams.
Sap Quarrymen's term for ferruginous discoloration along sheet or joint surface.
Schist A rock made up of flattish particles arranged in rough parallelism, some or all of which have crystallized under pressure.
Schistosity The quality of being like a schist.
Seam Quarrymen's term for joint.
Secondary Minerals Minerals whose presence is due to the alteration of the original minerals.
Sedimentary A term designating those rocks that consist of particles deposited under water.
Segregation The scientific term for "knot;" a collection of material separated from other material. A vein of segregation is one formed by the filling of a fissure with mineral matter originating in the surrounding rock.
Sericite A more or less fibrous form of muscovite (potash mica), often resulting from the alternation of feldspar.
Shakes Quarrymen's term to designate a somewhat minute close-joint structure, which forms along the sheet structure as a result of weathering.
Sheet Quarry A quarry in which the granite lies in sheets, crossed by wide-spaced steep joints.
Slickensides The polished and grooved faces of a joint or bed caused by motion and friction.
Specific Gravity The weight of a rock or mineral compared to that of a body of distilled water of the same bulk.
Strain-sheet The weight of a rock or mineral compared to that of a body of distilled water of the same bulk.
Stratifield A term applied to rock consisting of originally horizontal beds or strata.
Strike The direction at right angles to the inclination of a plane of bedding, a sheet, or joint, etc.
Stripping The material (sand, clay, soil, etc.) overlying a rock of economic value, which must be removed before quarrying.
Subjoint Minor joints diverging from or parallel to the regular joints.
Syncline A geological term for the trough part of a wave-like sheet or bed of rock.
Till A mixture of clay and bowlders deposited by glaciers.
Tillite Special name for the material of the till. The evidence that the clay and pebbles or boulders are of glacial origin is in the parallel striation of the pebbles or boulders owing to their having been rubbed against a rock while fixed in the moving ice.
Toeing-in Quarrymen's term for the wedging in of the end of a granite sheet under an overhanging joint, probably in consequence of the faulting of the sheets along the joint. It is also applied to the overlapping of lenticular sheets.
"Toenails" Curved joints intersecting the sheet structure, in most cases striking with the sheets, in some differing from them in strike 45° or more.
Twin Crystals Two adjacent crystals which have formed with the poles of their main axes in opposite or different directions.
Weathering The decomposition of a rock owing to the action of the weather.
White Horse Term used by quarrymen to denote a light-colored gneiss, aplite, or pegmatite.
Wollastonite A mineral consisting of silica 51.7 per cent and lime 48.3 per cent. It commonly results from the metamorphism of calcareous rock or marble where in contact with an igneous rock.

[Top of Page]