a. The outer portion of a stuffing box, having a tubular projection
embracing the rod, extending into the bore of the box, and bearing against
the packing. Standard, 2
b. The fixed engaging part of a positive-driven clutch.
Standard, 2

a. A visual sensation that can result in annoyance, discomfort, loss in
visual performance, or reduction of visibilty. There are three types of
glare: disability, discomfort, and reflected. Glare is a significant
factor in determining the design of underground coal mine illumination
systems.
b. See also:disability glare; discomfort glare.

glass

a. A state of matter intermediate between the close-packed, highly ordered
array of a crystal and the poorly packed, highly disordered array of a
gas. Most glasses are supercooled liquids, i.e., are metastable, but there
is no true break in the change in properties between the metastable and
stable states. The distinction between glass and liquid is made solely on
the basis of viscosity, and is not necessarily related, except indirectly,
to the difference between metastable and stable states. AGI
b. An amorphous product of the rapid cooling of a magma. It may constitute
the whole rock (e.g., obsidian) or only part of a groundmass.
CF:volcanic glass

glass-cloth screens

A device of clothlike material woven from glass fibers that is attached to
a metal frame to form a box- or basin-shaped receptacle, for filtering out
impurities from the incoming stream of molten aluminum before the metal
reaches the molds. Light Metal Age

glass electrode

A glass-membrane electrode used to measure pH or hydrogen-ion activity.
ASM, 1

glass enclosure

See:gas bubble

glassies

Octahedral diamond crystals (transparent). Hess

See:moldavite

See:hyalite

See:vitrophyre

A sand that is suitable for glassmaking because of its high silica content
(93% to 99%) and its low content of iron oxide, chromium, cobalt, and
other colorants. AGI

glass schorl

See:axinite

glass wool

See:mineral wool

glassy feldspar

Two varieties of potassium feldspar occur as transparent colorless
crystals, sanidine and adularia; also transparent yellow orthoclase and
transparent colorless albite. Syn:sanidine

glauberite

A monoclinic mineral, Na₂ Ca(SO₄ )₂ ; slightly salty
tasting; in evaporite deposits and fumarolic crusts; a source of sodium
sulfate.

Glauber salt

See:mirabilite

glaucocerinite

A hexagonal mineral, (Zn,Cu)₁₀ Al₆ (SO₄ )₃
(OH)₃₂ .18H₂ O ; forms soft, blue, fibrous-botryoidal
coating on adamite; associated with malachite, smithsonite, and gypsum at
Laurium, Greece.

glaucochroite

An orthorhombic mineral, CaMnSiO₄ ; occurs in prismatic crystals
associated with nasonite, willemite, garnet, axinite, and barite at
Franklin, NJ. CF:monticellite

glaucodot

An orthorhombic mineral, (Co,Fe)AsS ; pseudocubic, dimorphous with
alloclasite; in metallic prismatic crystals, or massive in cobalt ores
with cobaltite and pyrite. Also spelled glaukodot.

glaucolite

A blue or green variety of scapolite.

glauconite

a. A monoclinic mineral, 4[(K,Na)(Fe³⁺ ,Al,Mg)₂ (Si,Al)
₄ O₁₀ (OH)₂ ] ; mica group; basal cleavage; dull,
light to dark green; soft; a common authigenic mineral in marine
sediments, useful for radiometric ages for host rocks. Syn:greensand
b. A general term applied to green hydrous silicates of potassium and
iron. CF:celadonite