Next page Previous page

Istrian stone

A marble found near Trieste, from which Venice is largely built.
Fay

itabirite

A laminated, metamorphosed oxide-facies iron formation in which (1) the
original chert or jasper bands have been recrystallized into
megascopically distinguishable grains of quartz and (2) the iron is
present as thin layers of hematite, magnetite, or martite (Dorr & Barbosa,
1963). The term was originally applied in Itabira, Brazil, to a
high-grade, massive specular-hematite ore (66% iron) associated with a
schistose rock composed of granular quartz and scaly hematite. The term is
now widely used outside Brazil. CF:jacutinga; canga.
Syn:banded-quartz hematite; hematite schist. AGI

itacolumite

A micaceous sandstone or a schistose quartzite that contains interstitial,
loosely interlocking grains of mica, chlorite, and talc; exhibits
flexibility when split into thin slabs. Type locality is Itacolumi
Mountain in Minas Gerais, Brazil. Syn:flexible sandstone; articulite.
AGI

Italian asbestos

A name often given to tremolite asbestos to distinguish it from Canadian
or chrysotile asbestos; extensively quarried in Piedmont and Lombardy,
Italy. CMD

ivory

The fine-grained, calcareous creamy-white dentine forming most of the
tusks of elephants and the teeth or tusks of certain other large animals,
such as the walrus; it has long been esteemed for a wide variety of
ornamental articles. Elephant ivory is now illegal to use. It is often
simulated by bone.

ivory turquoise

Odontolite; fossil tooth or bone colored by a blue phosphate of iron.
Syn:bone turquoise

Iwan-pattern earth auger

A dry sampler equipped with an Iwan auger shoe or cutterhead.
See:post-hole digger

Ixiolite

A monoclinic mineral (Ta,Nb,Sn,Fe,Mn)4 O8 ) .

jacinth

See:essonite; hyacinth; zircon.

jack

a. A name for zinc ore; blackjack. See:sphalerite
b. Cannel coal interstratified with shale.
c. Coaly shale, commonly canneloid.
d. To drill a rock by hand, using a 4-lb (1.8-kg) hammer in one hand and a
steel drill in the other ("single jacking"). "Double jacking" is to use a
two-handed (sledge) hammer with the steel drill held by another worker.
e. A portable device used for exerting great pressure or for lifting a
heavy body through a small distance. Syn:anchor jack

jack boom

a. A boom that supports sheaves between the hoist drum and the main boom
in a pull shovel or a dredge. Nichols, 1
b. A boom whose function is to support sheaves that carry lines to a
working boom. Nichols, 1

jack catch

Safety catch in the rail track to stop tubs running back on inclines.
Mason

jack engine

Eng. A donkey engine; a small engine employed in sinking a shallow shaft.
Fay

jacket

An outer casing or cover constructed around a cylinder or pipe, the
annular space being filled with a fluid for either cooling, heating, or
maintaining the cylinder contents at constant temperature; e.g., the water
jackets of an internal combustion engine. CTD

jacket set

a. Set of timbers used in a shaft outside the regular shaft set, as extra
protection in heavy ground. Pryor, 3
b. Set like the larger shaft set with dividers omitted, except that the
wall and end plates are broken at all joints to facilitate renewing. Used
in heavy ground to protect the regular shaft timbers. The jacket set is
placed outside the regular timbers, separated from them by short blocks,
and is blocked and wedged against the rock. Lewis

jackhammer

A percussive type of automatically rotated rock drill that is worked by
compressed air. It is light enough to be used without a tripod and to be
hand held. Pryor, 3

jackhead

See:delivery drift

jackhead pit

a. A small pit without hoisting appliances, frequently serving as a
ventilation shaft. Standard, 2
b. A small shaft sunk within a mine. A winze. Fay

jackhead pump

A subordinate pump in the bottom of a shaft, worked by an attachment to
the main pump rod. Fay

jackhead set

Newc. The set of pumps in the jackhead staple. Fay

jackhead staple

Eng. A small mine for the supply of coal for the boilers. Fay