In this process, a stream of fluid carries the material to be separated
down a channel provided with draws for separating a heavy-gravity product
and means for overflowing a lighter one. If properly constructed and
operated, a comparatively solid bed of material will form on the bottom of
the launder. Above this bed, a layer of particles will move along by the
stream at a comparatively slow speed. Above this, successive layers will
move with greater and greater velocity. Mitchell
A type of coal washer in which the coal is separated from the refuse by
stratification due to hindered settling while being carried in aqueous
suspension through a trough. Modern launder washers have various
mechanisms for continuously removing refuse from the bottom of the trough.
Early launder washes were intermittent in operation.
The box at the surface receiving the water pumped up from below.
Fay
Hypothetical continent in the Northern Hemisphere that broke up about the
end of the Carboniferous Period to form the present northern continents.
An alkalic syenite containing more than 10% modal feldspathoids and
characterized by porphyritic texture. Also spelled lardalite. The name,
given by Broegger in 1890, is for Laurdal, Norway. AGI
A name that was originally applied to Precambrian granites of the
Laurentian Highlands, eastern Canada, and later to the oldest granites
near the U.S.-Canadian border northwest of Lake Superior.
An orthorhombic mineral, PbCl(OH) ; dimorphous with paralaurionite; in
ancient lead-ore slags.
An isometric mineral, RuS2 ; pyrite group; occurs with other
platinum-group minerals in ultramafic and placer deposits.
Unsaturated fatty acid, C12 H22 O2 . Pryor, 3
See:larvikite
A monoclinic mineral, Fe2 (SO4 )3 .6H2 O .
A monoclinic mineral, Ca(IO3 )2 .
Mill with three rolls, the middle roll being much smaller than the other
two. Only the two larger rolls are driven, work being performed between
the bottom and middle and middle and top rolls alternately; the roll
setting is adjusted between passes. Osborne
An orthorhombic mineral, CuAsS .
See:volcanic breccia
A dome-shaped mountain of solidified lava in the form of many individual
flows, formed by the extrusion of highly fluid lava, e.g., Mauna Loa, HI.
See also:shield volcano
A place where gold is obtained by washing. Standard, 2
A monoclinic mineral, (Na,Ca)2 (Mn,Fe)(Zr,Ti)Si2 O7
(O,OH,F)2 . Also spelled laavenite.
A metamorphosed basaltic rock with relict phenocrysts of labradorite in an
amphibolitic groundmass. The term was originated by Sederholm in 1899, who
named it after Lavia, Finland. AGI
A chromian variety of diopside. Also spelled lavroffite; lawrowite.