Next page Previous page

agglutination

See:cementation

aggradation

a. The building up of the Earth's surface by deposition; specif., the
upbuilding performed by a stream in order to establish or maintain
uniformity of grade or slope. See also:gradation
Syn:upgrading
b. A syn. of accretion, as in the development of a beach. The spread or
growth of permafrost, under present climatic conditions, due to natural or
artificial causes. AGI

aggregate

a. A mass or body of rock particles, mineral grains, or a mixture of both.
AGI
b. Any of several hard, inert materials, such as sand, gravel, slag, or
crushed stone, mixed with a cement or bituminous material to form
concrete, mortar, or plaster, or used alone, as in railroad ballast or
graded fill. The term can include rock material used as chemical or
metallurgical fluxstone. See also:chippings; coarse aggregate;
fine aggregate; lightweight aggregate. AGI

aging

A change in the properties of a substance with time. See also:overaging;
precipitation hardening. Nelson

Agitair flotation machine

Uses air to separate aerophilic and hydrophilic particles. Low-pressure
air bubbles lift aerophilic particles to an overflow, leaving hydrophilic
particles behind. Pryor, 3

agitation dredging

Consists of pumping the discharge directly into the sea and using the tide
to carry the fines to deeper water areas. Agitation dredging is employed
only during ebb tide in tidal estuaries having swift tidal flows that will
disperse the accumulations of silt. Carson, 2

agitation ratio

In older type gravity concentrators, such as tables and vanners, the ratio
between the average diameter of a mineral particle and the diameter of a
gangue particle that travels at equal speed.

agitator

a. A tank in which very finely crushed ore is agitated with leaching
solution. Usually accomplished by means of a current of compressed air
passing up a central pipe and causing circulation of the contents of the
tank. Sometimes called a mixer. CTD
b. A device used to stir or mix grout or drill mud. Not to be confused
with shaker or shale shaker. Long
c. A device used to bring about a continuous vigorous disturbance in a
pulp; frequently used to assist bubble formation. BS, 5
d. Pac. See:settler

aglaite

A pseudomorph of spodumene in which the spodumene has been replaced by
muscovite either as pinite or as visible plates. Also called pihlite and
cymatolite in the belief that the material was a new mineral. Hess

agmatite

Migmatite with appearance of breccia. CF:contact breccia

agnesite

An early name for bismutite, Cornwall, U.K. Fay

agonic line

An isogonic line that connects points of zero magnetic declination. Its
position changes according to the secular variation of the Earth's
magnetic field. See also:isogonic line

agreement

The formal document by which the contractor and the authority mutually
agree to comply with the requirements of the drawings, specification,
schedule, conditions of tendering, and general conditions of contract and
the tender. See also:tender; contract. Nelson

agricolite

A former name for eulytite.

agricultural geology

The application of geology to agricultural needs, e.g., mineral deposits
used as fertilizers or the location of ground water. Syn:agrogeology
AGI

agricultural lime

a. Either ground quicklime or hydrated lime whose calcium and magnesium
content is capable of neutralizing soil acidity. ASTM
b. Lime slaked with a minimum amount of water to form calcium hydroxide.
CCD, 2

agrite

A brown, mottled calcareous stone. Schaller

agrogeology

See:agricultural geology

aguilarite

An orthorhombic mineral, Ag4 SeS .

ahlfeldite

A monoclinic mineral, NiSeO3 .2H2 O; forms a series with
cobaltomenite; rose colored; vitreous luster; no cleavage; conchoidal
fracture; strongly pleochroic, X rose, Y pale green, Z brown green; from
Pacajake, Bolivia. Am. Mineral., 1

A-horizon

In a soil profile, the uppermost zone from which soluble salts and
colloids have been leached and in which organic matter has accumulated.
See also:B-horizon