A crystalloblastic rock consisting mainly of amphibole and plagioclase
with little or no quartz. As the content of quartz increases, the rock
grades into hornblende plagioclase gneiss. CF:feather amphibolite
AGI
The set of metamorphic mineral assemblages (facies) in which basic rocks
are represented by hornblende + plagioclase, the plagioclase being
oligoclase-andesine or some more calcic variety. Epidote and almandine are
common in amphibolites. The facies is typical of regional dynamothermal
metamorphism under moderate to high pressures (in excess of 300 MPa) with
temperatures in the range 450 to 700 degrees C. AGI
See:amphibolide
See:leucite
Having both acidic and basic properties. CTD
See:amygdule
An extrusive or intrusive rock containing numerous amygdules. Said of a
rock having numerous amygdules. Syn:amygdaloidal; mandelstone.
See also:amygdule
a. Said of rocks containing amygdules and of the structure of such rocks;
e.g., certain basaltic lava sheets on Keweenaw Point, Lake Superior, which
have amygdules filled with native copper, and are important sources of the
metal. Syn:amygdaloid; amygdule. AGI
b. Almond-shaped. Zern
A rock containing amygdules, or the structure of a rock resulting from its
presence. Schieferdecker
A gas cavity or vesicle, in an igneous rock, that is filled with such
secondary minerals as calcite, quartz, chalcedony, or a zeolite. The term
amygdale is preferred in British usage. Syn:amygdaloidal
See also:amygdaloid
C5 H11 OH ; a frothing agent. Pryor, 3
A powerful collector agent used in the flotation process. Pryor, 1
A bunch-blasting method in which 6 to 15 fuses, cut to respective lengths
2 in (5.1 cm) longer than required, are tied together near one end by two
ravelings of fuse spaced about 5 to 6 in (12.7 to 15.2 cm) apart. A
special cutter cuts the fuses off evenly between the two ties, leaving the
fuses tied together and offering a smooth face of cut ends. Another bunch
is made from the fuses of the remaining holes in the round. By using a
short notched fuse as a spitter, the flame is directed against the cut end
of one bunch of fuses. As soon as this bunch ignites, it is held close to
the face of the second bunch, moving slowly to contact all fuses with the
flame from the first bunch. Bunches should be held at least 6 in back from
the end to avoid burning the hands. By this method, all the holes of a
round are fired in only two groups and by one spitter. Lewis
a. Said of an organism (esp. a bacterium) that can live in the absence of
free oxygen; also, said of its activities.--n. anaerobe. AGI
b. Said of conditions that exist only in the absence of free oxygen.
CF:aerobic
An isometric mineral, 16[Na(H2 O)(AlSi2 O6 )] ;
zeolite group; in white to slightly tinted radiating aggregates or
granular masses; a late primary or hydrothermal mineral in mafic igneous
rocks, an alkaline lake precipitate, and in silicic tuffs and tuffaceous
sandstones. Formerly called analcite.
An extrusive or hypabyssal igneous rock consisting mainly of analcime and
pyroxene (usually titanaugite). Feldspathoids, plagioclase, and/or olivine
may be present. Apatite, sphene, and opaque oxides may be present as
accessories. AGI
Replacement of feldspars or feldspathoids by analcime, usually in igneous
rocks during late magmatic or postmagmatic stages. Syn:analcitization
AGI
See:analcimization
A computer that operates with numbers represented by directly measurable
quantities (such as length, voltage, or resistance) in a one-to-one
correspondence; a measuring device that operates on continuous variables
represented by physical or mathematical analogies between the computer
variables and the variables of a given problem to be solved. AGI
a. Corresponding to or resembling something else in some way, as in form,
proportion, etc.
b. Designating that pole (end) of a pyroelectric crystal to which heating
gives a positive charge. CF:antilogous
Study of the qualitative or quantitative composition of materials.
Pryor, 3