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medium-volatile bituminous coal

The rank of coal, within the bituminous class of Classification D 388,
such that, on the dry and mineral-matter-free basis, the volatile matter
content of the coal is greater than 22% but equal to or less than 31% (or
the fixed carbon content is equal to or greater than 69% but less than
78%), and the coal commonly agglomerates. CF:bituminous coal
ASTM

medium voltage

In coal mining, voltage from 661 to 1,000 V. CF:high voltage;
low voltage. Federal Mine Safety

medmontite

A mixture of chrysocolla and mica. See also:cupromontmorillonite

meehanite

High-duty cast iron produced by ladle addition of calcium silicide.
Pryor, 3

meerschaum

See:sepiolite

meet

a. Eng. To keep pace with; e.g., to keep sufficient supply of coal at the
pit bottom to supply the winding engine. Fay
b. To come together exactly, as in survey lines from opposite directions.
Fay

meeting

a. A siding or bypass on underground roads. Fay
b. Newc. The place at middle-depth of a shaft, slope, or plane, where
ascending and descending cars pass each other. Fay

meeting post

A vertical timber at the outer edge of each of a pair of lock gates,
mitered so that the gates fit tightly when closed. Hammond

mega-

a. A prefix meaning large. As a prefix to petrological and other geologic
terms, it signifies parts or properties that are recognizable by the
unaided eye. Opposite of micro-. Stokes
b. A combining form meaning 1 million times; e.g., megavolt for 1 million
volts. AGI

megabar

A unit of pressure equal to 1 Mdyn/cm2 . Standard, 2

megacycle

A unit of 1 million cycles. CTD

megaphenocryst

A phenocryst that is visible to the unaided eye. AGI

megascopic

Said of an object or phenomenon, or of its characteristics, that can be
observed with the unaided eye or with a hand lens. Syn:macroscopic
CF:microscopic

megaseismic region

The most disturbed earthquake area. Schieferdecker

megaspore

Female spore; part of the reproduction organs of many coal measures
plants. See also:spore

Megator

A displacement type of pump operating on the eccentric principle.
Mason

megger

An electrical measuring instrument comprising a hand-operated generator
equipped with a governor, a moving measuring system consisting of a
voltage, and a current coil so disposed that the deflection of the moving
system is proportional to the ratio of voltage to current. Used to measure
insulation resistance and resistance to ground. It has been used to some
extent in electrical prospecting. AGI

Meigen's reaction

A test to distinguish calcite from aragonite. After boiling for 20 min in
a cobalt nitrate solution, aragonite becomes lilac, the color showing in
thin section, while calcite and dolomite become pale blue, the color not
showing in thin section.

meionite

A tetragonal mineral, 3CaAl2 Si2 O8 .CaCO3 ;
scapolite group; forms a series with marialite.

meizoseismal

Of or pertaining to the maximum destructive force of an earthquake.
Standard, 2

meizoseismal area

The most disturbed area within the innermost isoseismal line.
Schieferdecker