A sedimentary deposit laid down in the brackish water of an estuary,
characterized by fine-grained sediments (chiefly clay and silt) of marine
and fluvial origin mixed with a high proportion of decomposed terrestrial
organic matter; it is finer grained and of more uniform composition than a
deltaic deposit. AGI
a. The seaward end or the funnel-shaped tidal mouth of a river valley
where fresh water comes into contact with seawater and where tidal effects
are evident. AGI
b. A portion of an ocean or an arm of the sea affected by fresh water;
e.g., the Baltic Sea. AGI
c. A drowned river mouth formed by the subsidence of land near the coast
or by the rise of sea level. AGI
The angle formed between the true horizon and the actual plane of the etch
ring in an acid bottle as measured before capillarity corrections. Also
called apparent angle. See also:capillarity
Long
A marking, commonly in the form of minute pits, produced by a solvent on a
crystal surface; the form varies with the mineral species and the solvent,
but reflects the symmetry of the structure; also called etching figure.
A process of engraving in which lines, frosting, or roughening are
produced by an acid or mordant. Often used in studying the composition and
structure of metals, sandgrains, and crystals.
A line of demarcation between the etched and unetched portions of the
inside of an acid bottle, used to determine the inclination of a borehole
by an acid-dip survey. Long
A method, using a soda-lime glass tube partially filled with a dilute
solution of hydrofluoric acid, of determining the angle at which a
borehole is inclined at any specific point of its course below the collar.
See also:acid-dip survey
Regular surface marking developed by solvent action on smooth surface of
alloy or crystal, and characteristic for that specific substance. The
reagent used is an etchant, usually of an acid in water or alcohol.
Pryor, 3
See:etch line
The time required for a dilute solution of hydrofluoric acid of a specific
strength to etch the inside of an acid bottle enough so that the line of
demarcation between the etched and unetched portions of the acid bottle is
clearly discernible. Also known as etching time. Long
See:acid-etch tube
See:acetamide
See:alcohol
The study of the correct and incorrect nomenclature of gems, with emphasis
on clarifying names and terms that may mislead or deceive purchasers.
See acetylene.
A crosscutting intrusive body of plutonic rock that narrows downward.
Used as an electrolyte to transform coal into a tan-gray substance with a
relatively high hydrogen-to-carbon ratio.
A highly explosive liquid HOCH2 CH2 OH ; somewhat volatile;
nonfreezing; explosive base. Used as an antifreeze. Lewis
See:acetylene
a. Leucite nephelinite. AGI
b. A dark-colored extrusive rock intermediate in composition between
leucitite and nephelinite with phenocrysts of clinopyroxene in a dense
groundmass of leucite, nepheline, and clinopyroxene. The name is not
included in the IUGS classification of extrusive igneous rocks.
A collective name for fluid, viscid, and solid bitumens that are easily
soluble in organic solvents. Petroleum, ozokerite, elaterite, and asphalt
are examples. Tomkeieff