A term proposed by Clarke (1908) to replace acidic. Syn:silicic
CF:subsilicic; mediosilicic. AGI
Continuous; orebodies are often persistent in depth and metal contents.
von Bernewitz
A survey of radiation conditions at positions occupied by personnel
working near apparatus emitting radioactivity. NCB
Deep sorption of gas by liquid. Pryor, 3
A common term for crowbar, lever, or some such article used as a manual
aid in moving heavy objects. Crispin
A variety of alkali feldspar consisting of parallel or subparallel
intergrowths in which the potassium-rich phase (commonly microcline)
appears to be the host from which the sodium-rich phase (commonly albite)
exsolved; such exsolved areas may be visible to the naked eye, typically
forming strings, lamellae, blebs, films, or irregular veinlets; where
texture is invisible to the eye but can be resolved with a microscope, it
is microperthite. CF:antiperthite; cryptoperthite; microperthite.
A deep-seated igneous rock consisting of alkali feldspar with less than 3%
dark minerals. Feldspar, both orthoclase and albite, may be perthitically
intergrown as cryptoperthite or as anorthoclase. Hess
See:permeable
A monoclinic mineral, LiAlSi4 O10 ; perfect cleavage;
vitreous; resembles spodumene; a source of lithium salts; in granite
pegmatites.
Resembling a flower petal in form, appearance, or texture. Applied to the
structure seen in minerals that split into pieces with a smooth polished
concave-convex surface that fit into one another somewhat like the petals
of an unopened flower bud. Webster 3rd; Fay
A small drain valve. Nichols, 1
To fail gradually in size, quantity, or quality; e.g., the mine has
petered out. Also called peter out. Fay
The gradual thinning of a vein until it disappears.
Statistical Research Bureau
In the Petersen (or van Veen) type of grab, two semicircular buckets of
varying sizes are hinged along a central axis. The buckets are held apart
for lowering from a ship to the bottom by some form of catch. On striking
the bottom, this is released so that on hoisting, the buckets move around
on their axis, take a bite out of the sediment, and come together to form
a closed container. With this configuration, the rate at which the grab
hits the bottom affects the bite, and when the ship is drifting, a poor
sample may be obtained if the grab does not hit the bottom vertically.
See also:grab sampler
Abbrev. for pentaerythritol tetranitrate. See also:penthrite
Bennett
An explosive compounded of ammonium carbonate, nitrated wood or charcoal,
and saltpeter. Standard, 2
A process of fossilization whereby organic matter is converted into a
stony substance by the infiltration of water containing dissolved
inorganic matter (e.g., calcium carbonate, silica), which replaces the
original organic materials, sometimes retaining the structure.
Syn:petrification
See:petrifaction
See:tufa
An aggregate or cluster of tabular crystals of barite, forming chiefly in
sandstone, enclosing sandy grains within the crystals; sand cemented by
barite with the crystal form of the latter. Syn:barite rosette
See also:rosette
See:silicified wood