A monoclinic mineral, Ca3 Si2 O4 (OH)6 ; it is
formed as portland cement is hydrated under special conditions, and where
calcium silicate is autoclaved (as in sand-lime brick manufacture).
A fine fibrous variety of talc pseudomorphous after enstatite.
Syn:asbestine
A soft, waxy stone--such as pinite, pyrophyllite, or steatite--of a gray,
green, yellow, or brown shade; used by the Chinese to simulate jade for
carving small images, miniature pagodas, and similar objects.
Syn:figure stone; pagodite; lardite; lard stone.
A hexagonal mineral, (RE,Ca)Cu6 (AsO4 )3 (OH)6
.3H2 O ; mixite group. Lanthanum, yttrium, or cerium may
predominate among the rare earths.
a. A soft, pulverulent hydrated silicate of magnesium in Tuscany, IT, from
which floating bricks can be made. Fay
b. A light, chalky deposit of calcium carbonate formed in caverns or
fissures in limestone. Syn:rock milk
a. A kind of silica consisting mainly of chalcedony in variegated bands or
other patterns; commonly occupying vugs in volcanic and other rocks.
AGI
b. A translucent cryptocrystalline variety of variegated chalcedony
commonly mixed or alternating with opal and characterized by colors
arranged in alternating stripes or bands, in irregular clouds, or in
mosslike forms; occurs in virtually all colors, generally of low
intensity, in vugs in volcanic rocks and cavities in some other rocks.
CF:onyx
moss agate.
An impure variety of agate consisting of jasper with veins of chalcedony.
Syn:jaspagate
Opalized agate. Fay
A variety of silicified wood which resembles any variety of agate.
See:silicified wood
a. The formal geochronologic unit of lowest rank, below epoch, during
which the rocks of the corresponding stage were formed. AGI
b. A term used informally to designate a length of geologic time during
which the rocks of any stratigraphic unit were formed. AGI
c. A division of time of unspecified duration in the history of the Earth,
characterized by a dominant or important type of life form; e.g., the age
of mammals. AGI
d. The time during which a particular geologic event or series of events
occurred or was marked by special physical conditions; e.g., the Ice Age.
AGI
e. The position of anything in the geologic time scale; e.g., the rocks of
Miocene age. It is often expressed in years. See also:geologic age
AGI
A device placed in the rail track to arrest a forward runaway tram. The
front axle of a descending tram traveling at normal speed depresses the
catch and allows it to drop back in time for the back axle to pass over.
Should the tram be traveling at excessive speed, the tail end of the catch
arrests the rear axle. Mason
a. The manager of a mining property. Zern
b. On a civil engineering contract, the responsible representative of the
contractor, acting for him or her in all matters. Hammond
c. Before nationalization in Great Britain, the term referred to the chief
official of a large coal mine or group of mines under the same ownership.
After nationalization, the equivalent term is group manager.
Nelson
d. A chemical added to pulp to produce desired changes in climate of the
system. Pryor, 3
The ratio of daughter to parent isotope upon which the age equation is
based. For a valid age determination, (1) the isotope system must have
remained closed since solidification, metamorphism, or sedimentation, (2)
the decay constant must be known, and (3) the sample must be truly
representative of the rock from which it is taken. AGI
A coarse-fraction concentration method used in milling pebble phosphate in
which conditioned feed at 70% to 75% solids is placed on a flat conveyor
belt traveling at a rate of about 75 ft/min (22.9 m/min). Water sprayed on
the surface of the pulp aerates the pulp, causing agglomerates of
phosphate particles to float to the side of the belt for removal. The
silica fraction travels the length of the belt and is permitted to flow
off the opposite end. Baffles are positioned at appropriate points along
the belt to stir the material so that trapped phosphate particles are
given an opportunity to float. Concentrate from the first belts or rougher
operation is cleaned on a second belt for further silica removal. Tailings
from the cleaner belt are recycled to the rougher circuit. Arbiter
A coarse-fraction concentration method used in milling pebble phosphate
that is based on flowing reagentized feed over a submerged sloping,
stationary screen. Agglomerated phosphate particles float on top of the
screen and are recovered at the lower end. Sand particles pass through the
screen and are removed as a tailings fraction. Each screen section is
approx. 3 ft (0.9 m) wide by 4 ft (1.2 m) long and treats 2 to 3 st/h (1.8
to 2.7 t/h) of feed. Arbiter
A measure of the binding qualities of coal but restricted to describe the
results of coke-button tests in which no inert material is heated with the
coal sample. CF:agglutinating value
a. In beneficiation, a concentration process based on the adhesion of pulp
particles to water. Loosely bonded associations of particles and bubbles
are formed that are heavier than water; flowing-film gravity concentration
is used to separate the agglomerates from nonagglomerated particles.
Agglomeration also refers to briquetting, nodulizing, sintering, etc.
Gaudin, 1
b. See:kerosine flotation
A welded pyroclastic deposit characterized by vitric material binding the
pyroclasts, or sintered vitric pyroclasts. Also spelled agglutinite.
AGI
See:caking index
A measure of the binding qualities of a coal and an indication of its
caking or coking characteristics. Applicable with reference to the ability
of fused coal to combine with an inert material such as sand.
CF:agglomerating value
A laboratory test of the coking properties of coal, in which a
determination is made of the strength of buttons made by coking a mixture
of powdered coal and 15 to 30 times its weight of sand.