The processes of deformation in the Earth's crust that produce its
continents and ocean basins, plateaus and mountains, and major folds and
faults. Syn:tectonism
a. Transmitting infrared radiation. Webster 3rd
b. Allowing the free passage of the rays of heat as a transparent body
allows free passage of light. Standard, 2
A microscopic unicellular plant with an envelope (frustule) or outer
skeleton of hydrated silica, close to opal in composition, and usually in
two parts. Diatoms inhabit both fresh water and salt water, and in places
their frustules form masses of diatomaceous earth or shale hundreds of
feet thick.
Composed of or containing diatoms or their siliceous remains. AGI
See:diatomite
A light-colored soft friable siliceous sedimentary rock, consisting
chiefly of opaline frustules of the diatom, a unicellular aquatic plant
related to the algae. Some deposits are of lake origin, but the largest
are marine. Owing to its high surface area, high absorptive capacity, and
relative chemical stability, diatomite has a number of uses, esp. as a
filter aid and as an extender in paint, rubber, and plastics. The term is
generally reserved for deposits of actual or potential commercial value.
Syn:diatomaceous earth; kieselguhr; guhr; tripoli. Obsolete syn:
infusorial earth; tripoli-powder. See also:tripolite
AGI
A deep-sea deposit, resembling flour when dry, largely composed of the
frustules of diatoms and containing a small but variable proportion of
calcareous organisms and mineral particles. Holmes, 2
Having a single distinct diagonal cleavage; applied to certain crystals.
Standard, 2
A saprokol containing a large amount of diatoms. Tomkeieff
A breccia-filled volcanic pipe that was formed by a gaseous explosion.
AGI
2-methyl-l-butanol; a frother used in the flotation process.
Pryor, 1
A Wisconsin term for small cubic galena. Fay
Any clay or mudstone with a cuboidal fracture, as in the Kimmeridge clay.
Arkell
A term loosely used to refer to either the two colors observable in a
dichroic stone or the three colors in a trichroic stone.
Syn:twin colors
a. Pleochroism of a crystal, which is indicated by two different colors or
two shades of the same color. In plane-polarized light, dichroic minerals
change color upon rotation. CF:trichroism; pleochroism.
b. Color change owing to change in the spectrum of illumination; e.g.,
alexandrite, which is green in sunlight but red by tungsten incandescent
light. See also:chrysoberyl
c. The property of some surfaces to reflect light of one color while
transmitting light of another.
A former name for iron-rich cordierite that may have been the navigation
stone of the Vikings; reveals maximum light polarization in the southern
sky.
A salt containing the divalent (Cr2 O7 )2- radical.
a. An instrument designed to detect two of the different colors emerging
from pleochroic (that is, dichroic or trichroic) minerals. Contains a
rhomb of Iceland spar and a lense system in a short tube, and exhibits the
two colors side by side. See also:dichroic colors
b. An instrument to detect two colors transmitted by pleochroic minerals
and display them side-by-side.
A monoclinic mineral, (K,Ba)(Na,Ca)5 (Mn,Fe,Mg)14 Al(PO (sub
4) )12 (OH,F)2 ; forms a series with arrojadite.
A green, hydrous phosphate mineral, chiefly of manganese, iron, and
sodium. Fay
A monoclinic mineral, Al2 Si2 O5 (OH)4 ;
kaolinite-serpentine group; polymorphous with halloysite, kaolinite, and
nacrite, each having a different stacking order of identical layers
(polytypy); commonly in hydrothermal veins.