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thulite

An intense pink variety of zoisite containing manganese; an ornamental
stone.

Thum-Balbach process

A silver refining process using carbon cathodes, dore anodes, and a silver
nitrate-nitric acid electrolyte. The silver is scraped off the bottom as
crystals. Liddell

thumb-marked fracture

The minute ripples or thumbmarks characteristic of the fractured surface
of amethyst. CMD

Thum furnace

A gas-fired furnace esp. for the treatment of zinc ore that is high in
lead. Fay

thunderbolt

a. A stone or stony concretion, esp. if elongated and tapering, found in
the ground and ignorantly supposed to have fallen from the sky.
Standard, 2
b. A nodule or mass of iron pyrites found in English chalk formations.
Standard, 2

thunder egg

A popular term for a small, geodelike body of chalcedony, opal, or agate
that has weathered out of the welded tuffs or lava, particularly from
central Oregon. AGI

thuringite

A monoclinic mineral, [Fe(OH)2 (AlSi3 O10
)].3[(Mg,Fe)(OH)2 ] ; pseudohexagonal; forms monoclinic plates
having micaceous cleavage; an iron-rich chamosite.

thurl

S. Staff. To cut through from one working into another. Also spelled
thirl. Fay

thurling

A passage cut from room to room, in post-and-stall working.
See also:thirl; thirling. Fay

thwarting

A short tunnel driven between two or more veins where they are nearly
vertical. Nelson

thyratron

A gas-filled valve or tube in which the initiation of current in an
ionized gas or vapor is controlled by the voltage applied to a control
electrode. NCB

Thyssen gravimeter

An early gravity meter of the unstable equilibrium type. AGI

Tibet stone

A mixture of aventurine quartz and quartz porphyry that may be of various
colors and has been cut as ornamental or curio stones, in Russia.

ticket

a. A sealed bid for ore to be sold. Webster 3rd
b. The numbered check that the miner puts on his loaded car to inform the
weighmaster to whom the coal belongs. See also:tag; tally. Fay

tick hole

A small cavity in a rock; a vug. Fay

tidal flat

An extensive marshy or barren tract of land that is alternately covered
and uncovered by the tide, and consisting of unconsolidated sediment
(mostly mud and sand). It may form the top surface of a deltaic deposit.
See also:sabkha

tidal marsh

See:tidal flat

tide flat

See:tidal flat

tidelands

Technically lands overflowed during floodtide, but the term, by reason of
the so-called Tidelands cases, has been used to describe that portion of
the continental shelf between the shore and the claimed boundaries of the
States--3 miles or 9 miles (4.8 km or 14.4 km) at sea. Williams

tie

a. A beam, post, rod, or angle to hold two pieces together; a tension
member in a construction. Webster 3rd
b. One of the transverse supports to which railroad rails are fastened to
keep them to line, gauge, and grade. Webster 3rd
c. Linear or angular measurements or a combination of the two made for the
purpose of locating other points from points of known position. Ties may
be made to connect physical objects with the survey line, or to locate the
instrument point with reference to physical objects so that it can be
reestablished if lost. To tie in is to close a survey on itself or on
another survey, or to locate a point by means of ties. Seelye, 2

tieback

a. A beam serving the purpose similar to a fend-off beam, but fixed at the
opposite side of the shaft or inclined road. Fay
b. The wire ropes or stayrods that are sometimes used on the side of the
tower opposite the hoisting engine, in place of or to reinforce the engine
braces. Fay