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sand-sized - (4) particles 62.5 µm to 2 mm in diameter.

scarify - (3) to break the surface of the soil with a narrow bladed instrument.

scatterplot - (4) a graphical plot showing the distribution of data points between two axes.

secondary mineral - (4) a mineral formed by surface processes, usually at the expense of a previously- formed primary mineral. The result of alteration, dissolution, or precipitation.

sediment - (2) solid material, both mineral and organic, that is in suspension, is being transported, or has been moved from its site of origin by air, water, or ice and has come to rest on the earth's surface either above or below the water level.

sediment pond/settling pond - (4) natural or constructed drainage impoundment used to reduce the concentration of suspended particles in surface run-off water or mine effluent prior to re-use or discharge into the environment. Often a series of ponds are constructed to allow regular sediment removal. See also polishing pond.

sedimetary rocks - (3) rocks, such as sandstone, limestone, and shale, that are formed from sediments or from transported fragments deposited in water.

sedimentation - (3) the process or action of depositing sediment.

sediment yield - (3) the amount of sediment removed from a watershed over a specified period, usually expressed as tons, acre-feet, or cubic yards of sediment per unit area of drainage area per year.

sensitive species - (3) all species that are under status review, have small or declining populations, live in unique habitats, or need special management. Sensitive species include threatened, endangered, and proposed species as classified by the Fish and Wildlife Service and National Marine Fisheries Service.

seral - (3) pertaining to the successional stages of biotic communities.

shaft - (1) a vertical or inclined excavation in a mine extending downward from the surface or from some interior point as a principal opening through which the mine is exploited. A shaft is provided with a hoisting engine at the top for handling men, rock, or supplies, or it may be used only in connection with pumping or ventilating operations. Often, the interior is timbered in such a way that each entity has its own passageway or compartment (cage, ski, manway or pipe); (2) an excavation of limited area compared with its depth, made for access to underground mine workings; (4) vertical or inclined underground working excavated downwards. Commonly used for hoist-based transportation of workers and/or ore and waste rock.

sill - (4) a tabular igneous intrusion that parallels the planar structure of the surrounding rock.

silt-sized - (4) particles 2 µm to 62.5 µm in diameter.

slag - (1) the glassy residue from which metals have been removed at a smelter.

slaking - (4) the crumbling and disintegration of materials upon exposure to air and moisture. See also weathering

slime - (1) very small solid particles which are known to pass through a 400 mesh screen. Ore reduced to fine powder and held in suspension in water so as to form a kind of thin mud.

slope stability - (3) the resistance of any slope to failure by sliding or collapsing.

sluice (sluice box) - (2) a long trough-like box set at an incline of about 1:20 through which placer gravel is carried by a stream of water. The gravel is washed away while most of the gold or other heavy metals are caught by riffles or blankets on the floor of the sluice.

smelting - (1) the chemical reduction of a metal from its ore and certain fluxes by melting at high temperatures. The non-metallic material floated on top of the heavier metallic constituents in the molten state and remained in that position when it cooled and hardened.

soil - (4) the upper portion of non-lithified material that has been altered over a period of time as a result of plant growth, climate (including moisture and temperature effects), drainage, macro- and microorganism activity or topographical position, producing a product - soil - that differs from the parent material (regolith) in many physical, chemical , biological processes and morphological properties. Soil can develop from both natural and anthropogenic parent materials. Soil either serves as or has the potential to serve as a medium for the growth of terrestrial of wetland plants.

soil horizon - (3) a layer of soil or soil material roughly parallel to the land surface and differing from adjoining genetically related layers in physical, chemical, and biological properties or characteristics, such as color, structure, and texture.

soil profile - (3) a vertical section of the soil from the surface through all of its horizons.

soil structure - (3) the physical constitution of soil material as expressed by size, shape, and the degree of development of primary soil particles and voids into naturally or artificially formed structural units.

soil texture - (3) (4) the relative proportions of sand-sized, silt-sized and clay-sized particles in the soil-sized fraction.

solubility - (4) the quantity of solute that dissolves in a given volume and type of solvent, at a given temperature and pressure, to form a saturated solution. The degree to which compounds are soluble depends on their ability, and that of other dissolved species, to form ions and aqueous complexes in a particular drainge chemistry.

spawning gravels - (3) stream-bottom gravels where fish deposit and fertilize their eggs. The covering of these gravels with silt can block the supply of oxygen to the eggs or serve as a cementing agent to prevent fry from emerging.

speciation - (4) the chemical form in which an element is present or the process whereby various states or forms of an element become differentiated into ions.

specific conductance -

spoil - (3) overburden or waste excavated and redeposited in surface mining.

square set - (1) a set of vertical and horizontal timbers used to provide roof support.

stamp mill - (1) an apparatus consisting of a vertical steel stem with an iron foot or shoe that is lifted by a cam and dropped onto coarsely crushed ore. Weight is added to the stamp in the form of a bosshead and a renewable wearing plate, the shoe. This assembly is dropped onto the ore which is fed onto a renewable stationary plate called a die. The action is housed on a steel box called the battery box and usually five stamps in a row are included in one battery. In front of the battery box are renewable screens, usually of the 20 mesh size that receive the splash from the impact. The combined stem, bosshead, and shoe usually weigh 800-1000 lbs. The grinding capacity of each stamp is about 2 to 2.5 tons per 24 hour period.

stock (fish) - (3) a group of fish that is genetically self-sustaining and isolated geographically or temporally during reproduction. Generally, stock refers to a local population of fish. More specifically, stock refers to a local population, especially of salmon, steelhead, or other anadromous fish, that originates from specific watersheds as juveniles, and generally returns to its birth streams to spawn as adults.

strategic minerals - (3) minerals essential to the national defense for the supply of which during war we are wholly or partly dependent on sources outside the continental limits of the United States, and for which strict measures are needed to control conservation and distribution.

stratification (lake) - (3) in a lake, the presence of two or more horizontal layers of water of differing characteristics, such as density.

stream order - (3) a stream classification system based on the number of tributaries a stream has. The smallest unbranched tributary in a watershed is designated as a first order stream. A stream formed by the confluence of two first order streams is designated as second order stream, and so on.

strike - (1) the horizontal course or bearing of an inclined bed, stratum or vein, or the direction of a horizontal line in the plane of an inclined bed, stratum or vein.

strip mine - (4) a general term for open pit mine, usually used for coal mines. The term 'strip' may refer to the removal of the surface or that mining occurs in long, linear strips. In the latter case, coal may be mined by removing overburden, excavating the coal seam and filling the excavation with overburden removed from the adjacent strip.

stripping ratio - (4) the ratio of non-ore or non-coal material (lithified or non-lithified) that must be excavated to extract a given amount of ore or coal. A measure of the amount of material that must be excavated in order to remove the coal or ore grade material.

stope - (2) an underground excavation from which ore has been removed.

structural diversity (of a stream channel) - (3) within a stream channel, the diversity of objects that control water movement.

structure (stream channel) - (3) an object, usually large, in a stream channel that controls water movement.

subaqueous - (4) occuring under water.

submarine tailings disposal - (4) the disposal of tailings to deep-sea locations.

submergent vegetation - (3) aquatic plants that grow only within water and do not break the water's surface. See also emergent vegetation.

subsidence - (2) a sinking down of a part of the earth's surface due to the collapse of underlying underground openings.

subsoil - (3) the B horizon of soils with distinct profiles, or the soil below the plowed soil (or its equivalent of surface soil) in soils with weak profile development.

substrate - (3) the mineral or organic material that forms the bed of a stream; the base upon which an organism lives.

suction dredge - (3) a dredge in which material is lifted by being pumped through a suction pipe.

sulfate - (4) a mineral, compound or ion containing the radical SO4(2-).

sulfide - (4) an inorganic compound characterized by the linkage of S2(2-) and S(2-) with a metal or metalloid.

sulfide ore - (3) ore in which sulfide minerals predominate.

sulfide sulfur - (4) sulfur occuring in the oxidation state of -2. The analysis for sulfide-sulfur is one in a series of sulfur analyses that are a part of acid/base accounting.

summer range - (3) range that is grazed mainly during the summer growing season. See also winter range

surface mining - (2) the mining in surface excavations, including placer mining, open pit mining mining, removing ore from open cuts by hand or with mechanical excavating and transportation equipment, and the removal of overburden to uncover the ore.

Surface Mining Control and Reclamation Act of 1977 (SMCRA) - (3) a federal act that sets rules for surface mining and reclamation of mined land, providing for transfer of much authority to states with approved programs

suspended sediment - (3) the very fine soil particles that are maintained in suspension on water for a considerable time by the upward components of turbulent currents or because they are fine enough to form a colloidal suspension.

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