One of several minerals including monazite, in which Th replaces rare
earths; thorite, ThSiO4 ; and thorianite, ThO2 .
Three thorium nitrides have been reported: ThN, Th2 N3 , and
Th3 N4 . Dodd
Three thorium sulfides have been reported: Th4 S7 , Th (sub
2) S3 , and ThS . Crucibles made of these sulfides have been used
as containers for molten cerium. Dodd
A tetragonal mineral, Th(SiO4 )1-x (OH)4x ; may
contain up to 31% uranium; has zircon structure. Differs from thorite (1)
in being secondary, formed by the alteration of primary thorium minerals
including thorite itself; (2) in not being metamict but forming
crystalline aggregates; and (3) in containing essential (OH).
Syn:thorian gummite; mackintoshite; maitlandite.
A name for radon 220, a member of the thorium disintegration series;
symbol, Tn; emits alpha particles; and half-life, 5.5 s. Also called
emanation; thorium emanation. Handbook of Chemistry and Physics, 2
A mineral, Na2 (Th,RE)(Mn,Ta,Fe)H2 [(Si,P)O4 ] (sub
3) ; metamict; dark brown to black.
See:yttrotungstite
Vertical joints affecting all the strata, as opposed to cricks or looses,
oolite quarries, Northamptonshire, United Kingdom. Syn:upright joints
A monoclinic mineral, (Sc,Y)2 Si2 O7 ; may contain up
to 42% yttrium replacing scandium; weakly radioactive; grayish green where
fresh, altering to white to reddish gray; in pegmatites associated with
monazite, euxenite, beryl, struvite, and possibly fergusonite; the only
known mineral rich in scandium.
Heavy mineral suites increase in complexity with decreasing geologic age.
A yellowish-green, transparent, aqueous solution of potassium mercuric
iodide, having a maximum specific gravity of 3.19. Also known as Sonstadt
solution. Used in the sink-float process of mineral separation.
Holmes, 2
a. An extremely small vein, even thinner than a stringer. Fay
b. A more or less straight line of stall faces, having no cuttings, loose
ends, fast ends, or steps. Fay
c. To reeve rope or cable through a sheave or block and tackle.
Long
A name sometimes applied to a diamond crystal having the shape of an
octahedron. Long
A scoria in which the vesicle walls have burst and are represented only by
an extremely delicate three-dimensional network of glass threads.
See also:reticulite
See:goniometer
Ïd èê„ &ì„ z D J DICTIONARY TERMS:three-cone bit See:roller rock bit
[\B]three-cone bit[\N]
In seismic prospecting, the true dip of a reflection or refraction horizon
found by exploration and calculation. See:true dip
An axial symmetry operation requiring three repetitions to complete 360
degrees or return to identity. Syn:triad
Consists of three horizontal rolls, one above the other, each rotating
continuously in one direction only, the piece being rolled between the
bottom and middle, and middle and top rolls alternately. Osborne
An arch hinged at its abutments and at its crown with the advantage that
each half can sink in relation to the other without damaging the arch.
Hammond
A drill chuck having three serrated-face movable jaws that can be made to
grip and hold fast an inserted drill rod. See also:chuck
In crystallography, a crystal of three parts united by the same twinning
law. Syn:trilling