The development of poikilitic texture by the formation of inclusions and
cavities along particular crystal planes, largely by solution somewhat as
are etch figures. Fay
Obsidian with schiller effect.
An altered enstatite or bronzite, having approx. the composition of
serpentine. Syn:bastite
A strongly foliated crystalline rock, formed by dynamic metamorphism, that
can be readily split into thin flakes or slabs due to the well developed
parallelism of more than 50% of the minerals present, particularly those
of lamellar or elongate prismatic habit, e.g., mica and hornblende. The
mineral composition is not an essential factor in its definition unless
specif. included in the rock name, e.g., quartz-muscovite schist.
Varieties may also be based on general composition, e.g., calc-silicate
schist, amphibole schist; or on texture, e.g., spotted schist.
See also:magnesian schist; pelitic schist. CF:paraschist
AGI
Said of a rock displaying schistosity. AGI
The foliation in schist or other coarse-grained, crystalline rock due to
the parallel, planar arrangement of mineral grains of the platy,
prismatic, or ellipsoidal types, usually mica. It is considered by some to
be a type of cleavage. Adj: schistose. AGI
A light-red variety of manganoan pectolite. See:pectolite
a. Tabular bodies, generally a few inches to tens of feet long, that occur
in plutonic rocks. They have the same general mineralogy as the rocks, but
because of differences in mineral ratios, they are darker or lighter; the
boundaries with the plutonic rock tend to be transitional. Some schlieren
are modified inclusions, others may be segregations of minerals. Etymol:
German. Sing: schliere. Also spelled schliere. Adj: schlieric.
CF:flow layer
b. Regions of different density in fluid, esp. as shown by special
apparatus. Hunt
c. A method or apparatus for visualizing or photographing regions of
varying density in a field of flow. Hunt
Apparatus used to determine the position of rest of a freely swinging
shaft plumbline. BS, 7
Schmidt-type magnetic field balance
This has been the most commonly used magnetic instrument for prospecting
on land. It consists of a magnet pivoted near but not at its center of
mass, so that the magnetic field of the earth creates a torque around the
pivot that is opposed by the torque of the gravitational pull upon the
center. The angle at which equilibrium is reached depends on the strength
of the field. Readings are taken through an eyepiece by comparing a scale
reflected from a mirror on the magnetic element with a fixed scale. The
balance may be either the horizontal or vertical type. Dobrin
A monoclinic mineral, Cu2 Pb2 (SeO3 )(SeO4
)(OH)4 ; light blue; at La Rioja, Argentina. Also spelled
schmeiderite.
A distillation furnace for the reduction of zinc ores containing lead,
with a recovery of the latter metal as well as the zinc. Fay
A monoclinic mineral, Al2 (PO4 )(VO4 ).8H2 O ;
yellow-orange.
The mineral group burtite, natanite, schoenfliesite, vismirnovite, and
wickmanite.
An orthorhombic mineral, UO3 .2H2 O ; strongly radioactive;
perfect cleavage; yellow; an alteration product of uraninite or
ianthinite. Formerly called schoepite I. Syn:epiianthinite
See also:metaschoepite; paraschoepite.
A method for determining the uranium in any of its ores in which the
uranium is extracted with dilute nitric acid. This extract is then
diluted, filtered, and treated with ferric chloride and sodium carbonate
causing the vanadium iron and aluminum to precipitate. The uranium is then
precipitated from the filtrate by boiling with caustic soda and purified
by solution in nitric acid. Following precipitating with ammonia, the
ammonium uranate is ignited to the oxide, and weighed. When this weight is
multiplied by the factor 0.847, it gives the weight of uranium.
An orthorhombic mineral, CaZn2 (PO4 )2 .2H2 O;
dimorphous with parascholzite; colorless to white.
An elutriator consisting of a tall glass vessel tapering toward the
bottom, where water enters at a constant rate. Schone's formula is: V =
104.7 (S#MN1)1.57 D1.57 where V is the velocity of water
(millimeter/second) required to carry away particles of diameter D and
specific gravity, S. Dodd
a. A black variety of tourmaline. Dana, 4
b. A discontinued term for schorl.
An isometric mineral, Ca3 Ti2 (Fe2 Si)O12 ,
with Ti decreasing toward andradite in the garnet group.
A term used in Cornwall, England, for a granular rock composed essentially
of aggregates of needlelike crystals of black tourmaline (schorl)
associated with quartz, and resulting from the complete tourmalinization
of granite. AGI