A tetragonal mineral, Mn2+ Mn3+6 SiO12 ;
brittle; may contain appreciable iron.
Ger. See:brown coal
A former name for a micaceous clay later shown to be a mixture of
montmorillonite and illite.
One of 14 ways points may be arrayed periodically in space such that each
point is in an identical point environment. Every crystal structure has
associated with it a Bravais lattice. Syn:space lattice;
crystal lattice. CF:direct lattice; space group.
See:Bravais rule
The most prominent faces of a crystal are those parallel to internal
planes having the greatest density of lattice points. Syn:Bravais law
A nickeloan variety of pyrite.
To solder with brass or other hard alloys. Nichols, 1
A monoclinic mineral, NaAl3 (PO4 )2 (OH)4 ;
yellow-green; also spelled brasilianite, brasilianita.
A colorless transparent quartz, such as is used for optical purposes.
Fay
A method for the determination of the tensile strength of rock, concrete,
ceramic, or other material by applying a load vertically at the highest
point of a test cylinder or disk (the axis of which is horizontal), which
is itself supported on a horizontal plane. The method was first used in
Brazil for testing concrete rollers on which an old church was being moved
to a new site. Dodd
a. A mixture of baddeleyite, zircon, and altered zircon.
b. A fibrous variety of baddeleyite.
c. An oil shale.
A type of twin found in quartz in which the two crystalline individuals
are of opposite kinds, one being right-handed, the other left-handed, with
a face of the trigonal prism of the second order as twinning plane. Since
one is not derivable from the other by any rotation, there is no twinning
axis. Hess
a. Joining metals by flowing a thin layer (capillary thickness) of
nonferrous filler metal into the space between them. Bonding results from
the intimate contact produced by the dissolution of a small amount of base
metal in the molten filler metal, without fusion of the base metal.
Sometimes the filler metal is put in place as a thin solid sheet or as a
clad layer, and the composite is heated as in furnace brazing.
ASM, 1
b. In joining metals, the term "brazing" is used where the temperature
exceeds some arbitrary value, such as 800 degrees F (427 degrees C); the
term "soldering" is used for temperatures lower than the arbitrary value.
ASM, 1
a. An opening made by breaking down a portion of a solid body, as a wall,
a dike, or a riverbank; a break; a gap.
b. The face of a level or drift.
c. A large cave hole caused by undermining.
An anticline whose crest has been deeply eroded, so that it is flanked by
inward-facing erosional scarps. CF:bald-headed anticline
The breaking through of a bar. Schieferdecker
N. Staff. A set of coal pillars formed by rearer workings. Nelson
a. A plane of discontinuity in the coal seam such as a slip, fracture,
joint, or cleat. The surfaces are in contact or slightly separated.
See also:break detector
b. A fracture or crack in the roof beds as a result of mining operations.
See also:breakes; induced fracture. Nelson
c. To separate core from solid rock at the bottom of a borehole by a
tensional pull applied to the drill string. Long
d. In mineral processing, optimum mesh of grind (m.o.g.), the practical
size range to which ore is reduced before concentration. Not synonymous
with liberation mesh. Pryor, 3
e. In drilling, to unscrew, as rods, casing, drill pipe, etc. Long
a. Voluntary or involuntary division of a solid. BS, 5
b. Small material produced by involuntary breakage during mechanical
handling or processing. BS, 5