Blacksmith's tongs. Standard, 2
A chemical sedimentary rock composed of calcium carbonate, formed by
evaporation as a surficial, spongy, porous, semifriable incrustation
around the mouth of a hot or cold spring or seep, or along a stream
carrying calcium carbonate in solution, and exceptionally as a thick,
bulbous, concretionary or compact deposit in a lake or along its shore. It
may also be precipitated by algae or bacteria. The hard, dense variety is
travertine. The term is rarely applied to a similar deposit consisting of
silica. It is not to be confused with tuff. Etymol: Italian tufo.
CF:sinter
petrified moss. AGI
Pertaining to or like tufa. Not to be confused with tuffaceous.
AGI
A general term for all consolidated pyroclastic rocks. Not to be confused
with tufa. Adj: tuffaceous. CF:crystal tuff
Said of sediments containing up to 50% tuff. CF:tufaceous
A pyroclastic rock consisting of more or less equal amounts of ash,
lapilli, and larger fragments. AGI
A tuff containing both pyroclastic and detrital material, but
predominantly pyroclasts. AGI
Applied to consolidated, lavalike tuff consisting primarily of lenses of
black and gray obsidian lying in a tuffaceous matrix that displays a
streaky, varicolored banding or eutaxitic structure. Rocks of this sort
are generally considered to be the product of ash flows or nue#1.es
ardentes. Syn:welded tuff
Eng. Any porous or soft stone, such as the sandstone in the Alston
district of Cumberland; tufa. AGI
a. Eng. Tufa near Newport, Monmouthshire, and Dursley, Gloucestershire.
b. Eng. Toadstone, Derbyshire. See also:toadstone
See:air hoist
An air hoist for mines. von Bernewitz
See:tugger operator
In mining, a person who operates a small portable or semiportable hoist
(tugger), powered by compressed air or electricity, to raise coal, ore,
rock, or supplies in a shaft or stope or along an incline inside a mine.
Also called tugger man. DOT
A tetragonal mineral, Na4 AlBeSi4 O12 Cl ; in the
Ilimaussaq massif, southwest Greenland. Formerly called beryllosodalite.
The working openings at the discharging end of a glass furnace.
Mersereau, 2
A method of determining the hardness of microconstituents by using the
Knoop or Vicker's type of diamond indenter. See also:microhardness;
Vickers hardness test. Henderson
To smooth, clean, or polish, as castings, by friction with each other or
with a polishing material in a rotating box or barrel; to rattle.
Standard, 2
Semiprecious and precious stones, cleaved carbon, or other diamonds, the
sharp edges and corners of which have been rounded and blunted by tumbling
action in a barrel-shaped vessel. Long
a. A projecting piece on a revolving shaft or rockshaft for actuating
another piece. In dredges, both an upper and a lower tumbler support the
bucket line. Fay
b. Any piece of equipment that polishes gemstones by a tumbling action.
Test for determining relative friability of a particular size of sized
coal. Bennett