marsh pan

A salt pan in a marsh. AGI

martenite

A synthetic fettling material, used for sintering open-hearth furnace
bottoms. The approximate composition (variable) is 5.2% silica, 2.1%
alumina, 10.5% ferric oxide, 13.4% lime, 66.5% magnesia (ignition loss,
2.3%). Martenite sinters more rapidly than magnesite, thereby reducing
repair time; moreover, it is suitable for hot patching. Martenite is as
wear resistant as magnesite and has no deleterious effect on the slag.
Osborne

martensite

Alpha-iron supersaturated with carbon as a result of quenching austinite
(gamma-iron) below 150 degrees C. (Not martinsite.)

martic

A mixture of bituminous matter, such as asphalt, and some foreign
material, such as sand. Mersereau, 2

Martin process

Used in the manufacture of steel. Also called Siemens-Martin and
open-hearth process. Fay

martinsite

See:kieserite

martite

Hematite pseudomorphous after magnetite octahedra.

martourite

See:berthierine

marundite

A coarse-grained pegmatite consisting of corundum and margerite with
accessory biotite, plagioclase, apatite, tourmaline, garnet, and kyanite.
Allied to plumasite grading into normal pegmatite. Hess

mascagnite

An orthorhombic mineral, (NH₄ )₂ SO₄ ; occurs around
fumaroles and in guano deposits.

mascot emerald

A beryl triplet that simulates emerald.

maser

Contracted version of microwave amplification by simulated emission of
radiation. A class of amplifier from which the optical laser was
developed. See also:laser

mask

a. A screen, usually made of tracing cloth, to subdue and diffuse the
light behind a plumbline or other sighted object. BS, 7
b. See:respirator

maskeeg

See:muskeg

maskelynite

A plagioclase glass in some chondrites and irons formed by preterrestrial
impact between meteorites in space.

mason's hammer

A square-faced hammer with a peen in line with handle. Standard, 2

mass

a. The quantity of matter in a body, obtained by dividing the weight of
the body by the acceleration due to gravity.
b. A large irregular deposit of ore, which cannot be recognized as a vein
or bed. See also:nontabular deposit

mass aqua

Borosilicate glass imitative of aquamarine (beryl).

mass copper

In the Lake Superior region, a term for native copper occurring in large
masses.

mass density

Mass of air per unit volume. Measured in kilograms per cubic meter.
Hartman, 2

mass detonation

A term applied to the unintentional detonation of all or a part of a large
quantity of explosive material (bulk truckload, shipload, or caseload) by
the explosion of a smaller quantity of explosives or a flame.