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achavalite

Former name for iron selenide, FeSe .

Acheson graphite

Artificial graphite made from coke by electric furnace heating.
Bennett

Acheson process

A process for the production of artificial or synthetic graphite. It
consists of sintering pulverized coke in the Acheson furnace at 2,760 to
3,316 degrees C. Henderson

achirite

Former name for dioptase.

achroite

A colorless variety of elbaite tourmaline used as a gemstone.

achromatic

In microscopy, a compound lens that does not spread white light into its
spectral colors. CF:aberration

acicular

a. A mineral consisting of fine needlelike crystals; e.g., natrolite.
Nelson
b. Slender needlelike crystal.
c. Refers to needlelike crystals. CF:equant; sagenitic; tabular;
rodlike.

acicular bismuth

See:aikinite

acicular powder

In powder metallurgy, needle-shaped particles. ASM, 1

aciculite

See:aikinite

acid

a. A solution of pH less than 7.0 at 25 degrees C.
b. A substance containing hydrogen that may be replaced by metals with the
formation of salts. CTD

acid Bessemer converter

One lined with acid refractories.

acid bottom and lining

The inner bottom and lining of a melting furnace, consisting of materials
like sand, siliceous rock, or silica brick, which give an acid reaction at
the operating temperature. Syn:acid lining

acid clay

a. A clay that is used mainly as a decolorant or refining agent, and
sometimes as a desulfurizer, coagulant, or catalyst.
b. A clay that yields hydrogen ions in a water suspension; a hydrogen
clay.

acid cure

In uranium extraction, sulfation of moist ore before leaching.
Pryor, 1

acid-dip survey

A method of determining the angular inclination of a borehole in which a
glass, test-tubelike bottle partly filled with a dilute solution of
hydrofluoric acid is inserted in a watertight metal case. When the
assemblage is lowered into a borehole and left for 20 to 30 min, the acid
etches the bottle at a level plane from which the inclination of the
borehole can be measured. CF:Kiruna method
acid test; acid-etch tube. Long

acid-dip test

See:acid-dip survey

acid drainage

Water with a pH of less than 6.0 and in which total acidity exceeds total
alkalinity; discharged from an active, inactive, or abandoned surface coal
mine and reclamation operation.

acid electric furnace

An arc furnace having an acid refractory hearth.

acid embrittlement

A form of hydrogen embrittlement that may be induced in some metals by
acid treatment. ASM, 1

acid-etch tube

A soda-lime glass tube charged with dilute hydrofluoric acid, left in a
borehole for 20 to 30 min to measure inclination as indicated by the angle
of etch line on the tube. May be fitted in a clinometer.
Syn:acid-etch vial; culture tube; etch tube; sargent tube.
See also:acid-dip survey