See:messelite
Chemical interchange within a rock whereby its mineral constituents are
converted into new mineral species; a type of recrystallization.
AGI
Said of the mineral grains of a rock that have been regenerated by zones
of secondary growth in crystalline continuity. The new material may have
been deposited from solutions or from molten fluids.
The function of the neoprene plug is to provide a completely waterproof
seal at the open end of the detonator. Moisture penetration could cause
desensitization of the explosive charge in the detonator, and in the case
of copper-tubed detonators, moisture could produce a potentially dangerous
chemical reaction between the lead azide and the copper. McAdam, 2
A hexagonal mineral, (Na,K)AlSiO4 ; feldspathoid group; greasy
luster; forms glassy crystals, colorless grains, coarse crystals with
prismatic cleavage, or masses without cleavage; occurs in alkalic igneous
rocks; an essential constituent of some sodium-rich rocks, e.g., nepheline
syenite. Formerly called nephelite; eleolite.
A plutonic rock composed essentially of alkali feldspar and nepheline. It
may contain an alkali ferromagnesian mineral, such as an amphibole
(riebeckite, arfvedsonite, barkevikite) or a pyroxene (acmite or
acmite-augite); the intrusive equivalent of phonolite. Sodalite,
cancrinite, hauyne, and nosean, in addition to apatite, sphene, and opaque
oxides, are common accessories. Rare minerals are also frequent
accessories. Syn:foyaite; eleolite syenite; midalkalite. AGI
A fine-grained or porphyritic extrusive or hypabyssal rock, of basaltic
character, but primarily composed of nepheline and clinopyroxene, esp.
titanaugite, and lacking olivine and feldspar. AGI
A nepheline-rich groundmass in an igneous rock; the glassy groundmass in
nepheline rocks. AGI
The process of introduction of or replacement by nepheline. AGI
The measurement of the cloudiness of a medium; esp. the determination of
the concentration or particle sizes of a suspension by measuring, at more
than one angle, the scattering of light transmitted or reflected by the
medium. CF:turbidimetry
An exceptionally tough, compact, fine-grained, greenish or bluish variety
of amphibole (specif. tremolite or actinolite) constituting the less rare
or valuable kind of jade. Syn:kidney stone; greenstone.
A dike filled by sediment, generally sand, in contrast to a plutonic dike
filled by volcanic materials. See also:sand dike
See:neptunism
The theory, advocated by A. G. Werner in the 18th century, that the rocks
of the Earth's crust all consist of material deposited sequentially from,
or crystallized out of, water. Etymol: Neptune, Roman god of waters.
CF:plutonism
A monoclinic mineral, KNa2 Li(Fe,Mn)2 Ti2 Si8
O24 ; forms red to black prismatic crystals; occurs in late stages
of reduced, silica-deficient environments; e.g., alkaline igneous rocks
and veins in serpentinite. See also:mangan-neptunite
Pertaining to the shallow seas; for accumulations of shells, but sometimes
for the whole environment of deposition on the continental shelf.
Challinor
That part of the sea floor extending from the low tide line to a depth of
200 m.
In ion exchange, the diffusion-layer supposed to surround a bead of resin.
This static film is reduced, or diffusion through it is accelerated, if
agitation of the ambient liquor is increased, if temperature is raised, or
if concentration of ions in solution is made greater. Pryor, 3
A black marble found in Roman ruins, probably from the Taenarian
peninsula, Greece.
An orthorhombic mineral, Mg(HCO3 )(OH).2H2 O ; forms
low-temperature efflorescences, particularly as an alteration product of
lansfordite. Named for a coal mine at Nesquehoning, PA.
A British term used esp. in Scotland for a promontory, headland, or cape,
or any point or projection of the land into the sea; commonly used as a
suffix to a place name, e.g., Fifeness. Also called nose. AGI