photomagnetic borehole surveying
A method of borehole surveying, consisting essentially of a timing clock,
batteries and light bulb, a floating light-transparent compass, an
inclination unit, and a photographic film for recording both the position
of the compass and the crosshairs of the inclinometer. The instrument is
enclosed in a nonmagnetic casing.
See also:multishot gyroscopic instrument
Nelson
A dust-sampling method in which samples of dust are collected on filter
paper and then placed in a photometer. The instrument shows the intensity
of a beam of light after it has passed through the paper, and the fall in
intensity is a direct measure of the dust concentration. With dark dust,
such as in coal mines, a rough indication of the dustiness may be obtained
by comparison of the depth of tone with a graded series of samples that
have been calibrated against some other instrument. There are two methods
of collecting samples for photometric estimation: (1) by passing the air
through a filter paper, as for gravimetric estimation; or (2) by
impingement, as in the konimeter. Spalding
A photographic enlargement of a microscopic image such as a petrologic
thin section; a type of micrograph. Less-preferred syn: microphotograph.
Webster 3rd
A sensitive detector of light in which the initial electron current,
derived from photoelectric emission, is amplified by successive stages of
secondary electron emission. NCB
A discrete quantity of electromagnetic energy. Photons have momentum but
no mass or electrical charge. Lyman
Term applied to minerals (e.g., chlorargyrite, utenbogaardite) that are
visibly injured by light.
A method of reproducing a drawing on opaque paper by printing from a
photographic negative, which enables the original drawing to be enlarged
or reduced. Hammond
A ground-surveying instrument used in terrestrial photogrammetry,
combining the functions of a theodolite and a camera mounted on the same
tripod. AGI
The reversible change in color of a substance produced by the formation of
an isomeric modification when exposed to radiant energy (such as light).
Webster 3rd
Peat composed of reed grass and other grasses. Tomkeieff
Pertaining to ground water. AGI
A volcanic eruption or explosion of steam, mud, or other material that is
not incandescent; it is caused by the heating and consequent expansion of
ground water due to an underlying igneous heat source. AGI
Any of the vapors and gases of atmospheric or oceanic origin which, coming
into contact with ascending magma, may provide the motive force for
volcanic eruptions. CTD
See:line of seepage
See:water table
A term that originally was applied only to water that occurs in the upper
part of the zone of saturation under water-table conditions (syn. of
unconfined ground water, or well water), but has come to be applied to all
water in the zone of saturation, thus making it an exact syn. of ground
water. AGI
Substance used in flotation processes to control the hydrogen-ion
concentration. See also:pH
Siliceous shale. The term is used esp. by European geologists. Also
spelled phtanite. AGI
Miner's occupational disease, a form of lung consumption associated with
or aggravated by work in dusty surroundings, such as badly ventilated
underground workings. See also:pneumoconiosis
Hydrothermal alteration typically resulting from removal of sodium,
calcium, and magnesium from calc-alkalic rocks, with pervasive replacement
of silicates, muting the original rock texture. It is a common style of
alteration in porphyry base-metal systems around a central zone of
potassic alteration. See also:propylitization