The upper part of the lithosphere in which rocks are under stresses less
than the stresses required to close their interstices by deformation of
the walls of the interstices. AGI
A subsurface zone in which all the interstices are filled with water under
pressure greater than that of the atmosphere. This zone is separated from
the zone of aeration (above) by the water table. Syn:saturated zone;
phreatic zone. AGI
The zone in which supergene enrichment has taken place.
zone of substantial deformation
See:destressed area
The superficial layer of the Earth's crust above the water table that is
subjected to the destructive agents of the atmosphere and in which soils
develop. CF:zone of cementation
A purification technique in which a molten or high-temperature zone is
moved along a length of material to be purified to bring about impurity
segregation; the impurities become concentrated in the slowly moving hot
zone, leaving behind the cooler solidified material that has a higher
purity than the original material. The technique depends on differences
in composition of liquids and solids in equilibrium and may be repeated
to attain high degrees of purity. It usually is applied to crystalline
materials, such as germanium or silicon.
In a shaft furnace, the different portions (horizontal sections) are
called zones, and are characterized according to the reactions that take
place in them, as the zone of fusion or smelting zone, the reduction zone,
etc. Fay
A lode may be divided into three main zones: (1) unaltered ore at depth;
(2) gossan or altered surface portion of the lode, which contain native
metals, oxides, and oxysalts that result from weathering of the ore; and
(3) secondary enrichment which lies between the first two zones, where
interaction between waters from the gossan and the unaltered ore have
produced new materials, often of considerable economic value.
Nelson
Standard time applied at sea in which the surface of the globe is divided
into 24 zones of 15 degrees , or of 1 h, each. The "0 zone" extends 7.5
degrees east and west of the meridian of Greenwich (England), (the Prime
Meridian); the zones are designated by the number of hours that must be
applied to the local time to obtain Greenwich time. Abbrev., ZT.
Webster 3rd
a. In ore deposits, the spatial distribution patterns of elements,
minerals, or mineral assemblages. AGI
b. A variation in the composition of a crystal from core to margin, due to
a separation of the crystal phases during its growth, by loss of
equilibrium in a continuous reaction series. The higher-temperature phases
of the isomorphic series form the core, with the lower-temperature phases
toward the margin. Syn:zonal structure
c. Concentric layering parallel to the periphery of a crystal, shown by
color banding, such as in tourmaline, and by differences in optical
reactions to polarized light, such as in plagioclase feldspar.
CF:undulatory extinction
d. In a mineral deposit, the occurrence of successive minerals or elements
outward from a common center.
e. The development of areas of metamorphosed rocks that may exhibit zones
in which a particular mineral or suite of minerals is predominant or
characteristic, reflecting the original rock composition, the pressure and
temperature of formation, the duration of metamorphism, and whether or not
material was added or removed.
Spatial distribution patterns of elements, minerals, or mineral
assembalages; paragenetic sequences, either syngenetic or epigenetic.
Zoning is esp. well developed in the mineralization-alteration assemblages
about subvolcanic occurrences such as porphyry base-metal deposits.
See also:zonal theory
A name that has been used in Arizona for locally occurring jasper or chert
of various colors.
A light and dark green variety of pumpellyite in green pebbles of banded
structure; occurs in the Lake Superior region, MI.
A trade name for a light, flaky material obtained by roasting vermiculite,
which swells to 15 times its original volume, forming golden yellow
scales; from Libby, MT. A titanium-bearing jefferisite from Westcliffe,
CO., is similar. English
The animal forms of plankton, e.g., jellyfish. They consume phytoplankton.
AGI
A brass-yellow metallic mineral with dark yellow streak; possibly
clausthalite with umangite.
Any of the Dow series of xanthate flotation reagents. Pryor, 3
An isometric mineral, Al13 Si5 O20 (OH,F)18 Cl;
occurs in transparent tetrahedral crystals, also minute cubes; at the
Zuni Mine, Silverton, CO. Also spelled zungite.
A rawhide sack that holds about 150 lb (68.1 kg); used by miners for
carrying ore. Nelson
A monoclinic mineral, (Fe,Mn)2 (PO4 )F; forms a series with
triplite; clove-brown.