A form of chemical weathering in which concentric or spherical shells of
decayed rock (ranging in diameter from 2 cm to 2 m) are successively
loosened and separated from a block of rock by water penetrating the
bounding joints or other fractures and attacking the block from all sides.
It is similar to the larger-scale exfoliation produced usually by
mechanical weathering. See also:spheroidal parting
Syn:onion-skin weathering; concentric weathering; spherical weathering.
CF:exfoliation
A variety of siderite occurring in globular concretionary aggregates of
bladelike crystals radiating from a center, generally in a clayey matrix
(such as those in or below underclays associated with coal measures). It
appears to be the result of weathering of water-logged sediments in which
iron, leached out of surface soil, is redeposited in a lower zone
characterized by reducing conditions. Also spelled sphaerosiderite.
a. A rounded or spherical mass of acicular crystals, commonly of feldspar,
radiating from a central point. Spherulites may range in size from
microscopic to several centimeters in diameter. Also spelled: sphaerolite.
AGI
b. Any more or less spherical body or coarsely crystalline aggregate with
a radial internal structure arranged around one or more centers, varying
in size from microscopic grains to objects many centimeters in diameter,
formed in a sedimentary rock in the place where it is now found; e.g., a
minute particle of chalcedony in certain limestones, or a large carbonate
concretion or nodule in shale. CF:spherite; variole. AGI
c. A small (0.5 to 5 mm in diameter), spherical or spheroidal particle
composed of a thin, dense calcareous outer layer with a sparry calcite
core. It can originate by recrystallization or by biologic processes.
AGI
Said of the texture of a rock composed of numerous spherulites; also, said
of a rock containing spherulites. CF:variolitic; radiated.
Syn:globular; sphaerolitic. AGI
a. A ring inserted at the joints of the suspension column of a borehole
pump. Radial vanes from the ring support a central sleeve, which acts as a
steady bearing from the pump shaft. BS, 10
b. The bowl part of a spider and slips. Also called bowl.
See also:spider and slips
c. See:drum horn
d. Assembly of radiating tie rods on the top of a furnace. ASTM
A gripping device used to grip and hold rods or casing while coupling or
uncoupling them as they are being run into or pulled from a borehole. Also
called bowl and slips. See also:spider
A differential gear that rotates on its shaft in a rotating case.
Nichols, 1
A local term in Ohio for sandstone beds that show crossbedding on a small
scale, which is complicated by intricate interlacing of fine-bedding
planes. Frequently seen in sawed stones, esp. where the lamination is
slightly oblique or irregular. It is very like the grain of wood that
shows in a planed board.
An alloy containing 10% to 25% manganese. Is used in steelmaking as a
deoxidizing agent and to raise the manganese content of the steel. Also
called spiegel and psiegel iron. CTD; Henderson; Camp
In ore dressing, the material discharged at the bottom of the hydraulic
classifier. Newton, 1
A cylindrical amygdule whose longer axis is at right angles to the
bedding.
In bituminous coal mining, one who drives a team of two or more draft
animals in tandem for hauling wagons or cars of coal. Also called
spike-team driver. DOT
a. A team consisting of three draft animals, two of which are at the pole
while the third pads. Fay
b. Three mules, two abreast and one in the lead, used in a mine to haul
coal cars. Fay
See:spike driver
A term used in the United States for the operation of adding
ferromanganese, silicomanganese, or other deoxidizing agent, to an open
hearth bath for the immediate stoppage of all oxidizing reactions.
Osborne
a. A large timber driven into the ground, used as a foundation; a pile.
Crispin
b. A plank driven ahead of a tunnel face for roof support. Also called
forepole. Nichols, 1
c. A temporary lagging driven ahead on levels in loose ground.
See also:spill
d. A short piece of plank sharpened flatways and used for driving into
watery strata as sheet piling to assist in checking the flow.
An ironstone miner who excavates and sets timber supports in roadways
through wastes and disturbed ground. Nelson
An instrument resembling the bathythermograph and operating in a similar
fashion, with the additional ability of obtaining water samples at
discrete depths within the limit of operation. Basically, a
bathythermograph to which 12 small seawater sampling bottles are attached,
it performs the same functions as a cast of Nansen bottles and reversing
thermometers to limited depths, but with less accuracy. It is useful for
studies of shallow water areas, bays, and estuaries, where rapidity of
sampling is of greater importance than the degree of accuracy of
temperatures. Hunt
a. Forepoling over timber and steel supports in weak, loose beds.
See also:spilling
b. Driving timbers ahead of an advancing tunnel through treacherous,
loose, watery ground. Pryor, 3
An altered basalt, characteristically amygdaloidal or vesicular, in which
the feldspar has been albitized and is typically accompanied by chlorite,
calcite, epidote, chalcedony, prehnite, or other low-temperature hydrous
crystallization products characteristic of a greenstone. Spilite often
occurs as submarine lava flows and exhibits pillow structure. Adj:
spilitic. The name was given by Brongniart in 1827. AGI
A group of altered extrusive and minor intrusive basaltic rocks that
characteristically have a high albite content. The group is named for its
type member, spilite. AGI