Next page Previous page

mill-head ore

See:run-of-mill

mill hole

An auxiliary shaft connecting a stope or other excavation with the level
below. See also:mill; glory hole. Lewis

milli-

A prefix meaning one thousandth of. It divides a basic unit by 1,000, or
multiplies it by 10-3 ; abbrev., m. Commonly applied to units of
measure in the metric and cgs systems; e.g., 1 mg = 0.001 g. Lyman

milliampere

One-thousandth of an ampere; abbrev., mA. Crispin

milliangstrom

One-thousandth of an angstrom; abbrev., mAa. Webster 3rd

millibar

A unit of atmospheric pressure equal to one-thousandth of a bar or 1,000
dyn/cm2 ; abbrev., mb. Webster 3rd

millicurie-hour

A measure of gamma-ray exposure expressed as the product of the source in
millicuries and the time of exposure in hours. NCB

millidarcy

The customary unit of measurement of permeability, equal to one-thousandth
of a darcy. See also:permeability
AGI; Webster 3rd

millidegree

A unit of temperature equal to one-thousandth of a degree; abbrev., mdeg.
Webster 3rd

millifarad

One-thousandth of a farad; abbrev., mF. Webster 3rd

milligal

a. A unit employed in the gravitational method of geophysical prospecting.
It is about one millionth of the average value of the acceleration due to
gravity at the Earth's surface; i.e., 1 milligal = 1 cm/s2 .
Nelson
b. A unit of acceleration used with gravity measurements; 10-3
Gal = 10-5 m/s2 . Abbrev: mGal. AGI

milligauss

One-thousandth of a gauss; abbrev., mG. Standard, 2

milligram-hour

A measure of gamma-ray exposure expressed as the product of the equivalent
radium content of the source, in milligrams, and the time of exposure in
hours. NCB

millihenry

One-thousandth of a henry; a unit of inductance; abbrev., mH.
Webster 3rd

millimeter screw micrometer

A precision caliper gage that measures the overall dimensions of unmounted
fashioned gems more accurately but less conveniently than dial gages.

milling

a. The grinding or crushing of ore. The term may include the operation of
removing valueless or harmful constituents and preparation for market.
Nelson
b. A combination of open-cut and underground mining, wherein the ore is
mined in open cut and handled underground. It is underhand stoping applied
to large deposits, wherein the ore is mined near the mouth of winzes or
raises, and dropped by gravity to working levels below for transportation
to the surface. Usually called glory-hole system. See also:mill
c. The act or process of cutting or grinding away a metal object lost in a
borehole with a mill or milling bit. Long

milling bit

A bit equipped with hardened serrations or teeth used to grind or cut away
metallic materials or junk obstructing a borehole. Also called rose bit.
CF:junk mill

milling grade

a. Ore containing sufficient recoverable value to warrant treatment.
Pryor, 3
b. S. Afr. An assumed average value of the ore sent to a mill, expressed
as a percentage, or in pennyweights per short ton. Beerman

milling ore

a. Any ore that contains sufficient valuable minerals to be treated by any
milling process. Syn:mill ore
b. A dry ore that can be amalgamated or treated by leaching and other
processes; usually these ores are low grade and free, or nearly so, from
base metals.

milling width

Width of a lode that is designated for treatment in a mill, as calculated
with regard to daily tonnage. Any excess broken during mining (stoping
width) should be rejected before milling. Pryor, 3

milling yield

S. Afr. The valuable material obtained from milling, expressed as a
percentage or in pennyweights per short ton. Beerman