Back-Up Curve – Curve on the analog record that displays log data on a new scale when deflections on the main curve exceed the width of the paper; usually displayed with a different pattern or color.
Backwash – Return flow of water down a beach after a wave has broken.
Bacterial Oxidation – BIOX is a process in which a combination of three bacteria are used to break down the sulphide mineral matrix in the ore being treated, thus freeing occluded gold for subsequent cyanidation. The bacteria attach themselves to the metal sulphide surfaces in the ore, resulting in the accelerated oxidation of the sulphides. During the bacterial oxidation process, elements like iron, sulphur and arsenic are dissolved.
Ball Mill – A steel cylinder filled with steel balls into which crushed ore is fed. The ball mill is rotated, causing the balls to cascade and grind the ore.
Banded Iron Formation – Rock consisting of alternating light and dark layers of iron-rich chert (hematite and limonite) formed approximately 3,800 million years ago.
Bankable Feasibility Study – A BFS is an extensive technical and financial study to assess the commercial viability of a project, of sufficient detail and integrity that it can be used to arrange and support project financing.
Bankfull Stage – Height of water in a stream that just corresponds to the level of the surrounding floodplain.
Bar ‘Unit’ – Unit of pressure equal to 10 to the sixth dynes/square centimeter; approximately one atmosphere.
Bar ‘Water’ – An accumulation of sediment, usually sandy, which forms at the borders or in the channels of streams or offshore from a beach.
Barasway – Body of water separated from the sea by a bar or ridge of sand, gravel, etc., built up by waves and currents. Also known as a lagoon.
Barchan – Crescent-shaped sand dune moving across a clean surface with its convex face upwind and its concave slip face downwind.
Bar-Finger Sand – Elongated lens of sand deposited during the growth of a distributary in a delta. The bar at the distributary mouth is the growing segment of the bar finger.
Barite – White, heavy mineral. The main ore of barium, used in paints, drilling muds and TV screens.
Barrier Island – Long, narrow island parallel to the shore composed of sand and built by wave action.
Basalt – Fine-grained, dark, mafic igneous rock composed largely of plagioclase feldspar, pyroxene and some olivine. The rough volcanic equivalent of gabbro.
Base Level – Level below which a stream cannot erode; usually sea level but sometimes locally the level of a lake or resistant formation.
Base Metal – Generally non-ferrous, non-precious metal such as copper, lead, nickel, zinc or cobalt.
Basement – Igneous and metamorphic rocks that underlie the oldest sedimentary formations. Often refers to rocks of Precambrian age which may be covered by younger rocks. In some areas such as shields, like the Canadian Shield, the basement rocks may be exposed at the surface.
Basement Rock – Oldest rocks recognized in a given area such as a complex of metamorphic and igneous rocks that underlie all the sedimentary formations. Usually Precambrian or Paleozoic in age.
Basic Rock – Any igneous rock containing mafic minerals rich in iron and magnesium, but containing no quartz and little sodium rich plagioclase feldspar.
Basin – Site of an accumulation of a large thickness of sediments or a tectonic, syncline-like depression of strata.
Batholith – Very large body of igneous intrusive rock, usually granite, that forms from cooled magma deep in the Earth’s crust
Bathymetry – Study and mapping of sea-floor topography.
Bauxite – Rock composed primarily of hydrous aluminum oxides and formed by weathering in tropical areas with good drainage. A major ore of aluminum.
Baymouth Bar – A narrow, usually submerged, ridge of sand and gravel deposited across the mouth of a bay. Commonly formed by the extension of spits and may connect two headlands, thus straightening the coast.
Bed – Layer in sedimentary rocks formed during deposition and reflecting different compositions or grain sizes in the original sediment.
Bedding – Characteristic of sedimentary rocks in which layers separating different grain sizes or compositions indicate successive depositional surfaces that existed at the time of sedimentation.
Bed-Load – Sediment that a stream moves along the bottom of its channel by rolling and bouncing.
Bedrock – Continuous, solid rock that underlies soil and unconsolidated loose sediment everywhere. An exposure of bedrock is called an outcrop.
Belt – Specific regional domain over an elongated area that is generally continuous for many kilometres hosting a series of mineral deposits occurring in close proximity to each other, often with a common origin. It often contains unique geologic characteristics.
Berg – Mass of floating or stationary ice.
Beta-Particle – Electron emitted with high energy and velocity from an atomic nucleus undergoing radioactive decay.
B-Horizon – Intermediate layer in a soil, situated below the A-horizon and consisting of clays and oxides. Often referred to as the zone of accumulation.
Biochemical Precipitate – Sediment, especially of limestone or iron, formed from elements extracted from seawater by living organisms.
Biostratigraphy – Study of rock layers based on their fossils; thus biostratigraphic.
Biostratinomy – Study of what happens between the death of an organism and burial.
Biotite – Dark-colored phyllosilicate mineral within the mica group containing potassium, aluminum, magnesium and iron which splits easily into thin, translucent sheets.
Biotites – Common rock-forming mineral in crystalline rocks, either as an original crystal in igneous rocks or as a metamorphic product in gneisses and schists.
Bioturbation – Disturbance of sediment by organisms.
Bituminous Coal – Most common grade of coal that is soft and formed by an intermediate degree of metamorphism, usually containing 15 to 20 percent volatiles.
Block Fault – Structure formed when the crust is divided into blocks of different elevation by a set of normal faults.
Blowout – Shallow circular or elliptical depression in sand or dry soil formed by wind erosion. Also a sudden escape of a confined gas or liquid, as from a well.
Blueschist – Metamorphic rock formed under great pressures, but not so great temperatures.
Bolson – Arid regions where a basins fill with alluvium and intermittent playa lakes that have no outlet.
Bore Hole – Drill hole created for exploring strata in search of minerals, or alternatively for blasting purposes or proving the position of old workings and faults.
Borehole – Compensated – Probes designed to reduce the extraneous effects of the borehole, casing, and of probe position are called borehole-compensated.
Borehole Television or Video – A downhole television camera.
Bornite – Bornite is an important copper ore mineral along with copper ores such as chalcocite, chalcopyrite, covellite, digenite, cuprite and tetrahedrite. In Bornite copper content is 50% atomic ratio.
Bottom-Hole Temperature – Bottom-hole temperature (BHT) is usually measured with maximum recording thermometers attached to a logging probe.
Boudinage – Layer, such as bed, dyke, etc., that has been pulled apart into sausage-like pieces.
Bouguer Correction – Process of correcting gravity data for the mass of the rock between a given station and its reference (base) station. Application of the Bouguer correction to the data set, as well as corrections for latitude, topography, meter drift and elevation, yields the Bouguer anomaly.
Bounds – Integrated approach to exploration where geophysical survey data is complemented by direct sampling and other geological information. As a consequence, inversions of geophysical survey data can be constrained by setting upper and lower bounds (cut-offs) on the model values.
Brachiopod – Type of shelled animal with two unequal shell halves, which usually lived attached to the seafloor by a stalk.
Brackish – Slightly salty.
Breccia – Rock consisting of angular fragments are surrounded by a mass of fine-grained minerals which may or may not be similar to the larger fragments. It may be formed from any rock type by fracturing (in a fault), explosion (volcanic), intrusion (intrusion breccia) or sedimentation (scree slope). The sharpness of the fragments indicates that they did not travel far from where they fractured.
Brute Stack – Common midpoint stack with only preliminary static corrections and preliminary normal-moveout corrections.
Bulk Density – Mass of material per unit volume; in logging. It is described as the density, in grams per cubic centimeter, of the rock with pore volume filled with fluid.
Bulk Modulus – Modulus of elasticity, relating change in volume to the hydrostatic state of stress. The opposite of compressibility.
Bushman Lineament – Surface expression of the Bushman Shear.
Butte – Steep sided, flat topped hill formed by erosion of flat laying strata where remnants of a resistant layer protect the softer rocks underneath.