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lefkasbestos

A bleached-white variety of asbestiform chrysotile from Mt. Troodos,
Cyprus.

left bank

The bank of a stream that is to the left of an observer facing downstream.

left lang lay

Wire or fiber rope or cable in which the wires or fibers in a strand and
the strands themselves are twisted to the left. Long

left-lateral fault

A fault on which the displacement is such that the side opposite the
observer appears displaced to the left. CF:right-lateral fault
Syn:sinistral fault

left long lay

See:left lang lay

left regular lay

Wire or fiber rope or cable in which the individual wires or fibers in the
strands are twisted to the right and the strands to the left.
Syn:regular-lay left lay

left twist

See:right lay

leg

a. In mine timbering, a prop or upright member of a set or frame. Also
called upright; post; arm. Pryor, 3; Nelson
b. One of the main upright members of a drill derrick or tripod.
Long
c. A term sometimes applied to a centrifugal discharge bucket elevator.
Usually a double leg bucket elevator.
d. See:draft
e. A side post in tunnel timbering. Nichols, 1

legend

A brief explanatory list of the symbols, cartographic units, patterns
(shading and color hues), and other cartographic conventions appearing on
a map, chart, or diagram. On a geologic map, it shows the sequence of rock
units, the oldest at the bottom and the youngest at the top. The legend
formerly included a textual inscription of, and the title on, the map or
chart. Syn:key

leg piece

The upright timber that supports the cap piece in a mine. CF:legs
Fay

legrandite

A monoclinic mineral, 8[Zn2 (AsO4 )(OH).H2 O] .

legs

a. The wires attached to and forming a part of an electrical blasting cap.
Fay
b. The uprights of a set of mine timbers. See also:dap; leg piece.
Fay

legua

Sp. Land league used in the original surveys of the Philippines,
California, and Texas. It is equal to 2.63 miles or 4.24 km.
See also:league

leg wire

One of the two wires attached to and forming a part of an electric
blasting cap or squib.

Lehigh jig

A plunger-type jig with the following distinguishing characteristics: (1)
the plunger contains check valves that open on the upstroke to reduce
suction; (2) the makeup water is introduced with the feed; (3) the screen
plate is at two levels, which have different perforations, to keep the
water distribution uniform; (4) the bottom of the discharge end of the jig
is hinged. This jig has been used extensively in washing anthracite.
Mitchell

lehiite

A mixture of crandallite with other minerals.

Lehmann process

A process for treating coal by disintegration and separation of the
petrographic constituents (fusain, durain, and vitrain). It consists of
subjecting the coal to resilient disintegrating or shattering action for a
sufficient length of time to break the constituents into granules of
various sizes by reason of their respective resistances to shattering
impacts and separating the granules into different sizes by screening or
equivalent means. Mitchell

lehr

An enclosed oven or furnace used for annealing, or other form of heat
treatment; particularly used in glass manufacture. It is a kind of tunnel
down which glass, hot from the forming process, is sent to cool slowly, so
that strain is removed, and cooling takes place without additional strain
being introduced. Lehrs may be of the open type (in which the flame comes
in contact with ware), or of the muffle type. Syn:leer; lear.
CTD

lehr man

Person who regulates temperature of a reheating oven (lehr) used to
fire-glaze glass articles. Arranges glass articles according to size and
shape on lehr conveyor so that maximum quantity will be carried in oven on
a long paddle. Also called leer man; lehr operator, glass; lehr tender.
DOT

lehrnerite

See:ludlamite

leightonite

A triclinic mineral, K2 Ca2 Cu(SO4 )4 .2H (sub
2) O ; pseudo-orthorhombic; blue; at Chuquicamata, Chile.