Breaking down large pieces of asbestos by means of short blastholes
judiciously placed. Sinclair, 7
A pressure-relief valve. Long
a. A pulley frame or the headgear over a shaft. A headframe.
b. A valve that lifts bodily from its seat instead of being hinged.
See also:poppet valve; puppet valve.
a. The top of a derrick where the pulley is situated. Gordon
b. See:headgear
A valve shaped like a mushroom, resting on a circular seat, and opened by
raising the stem. See also:poppet; puppet valve. Nichols, 1
The drilling, charging, and firing of a hole in the center of a boulder at
quarry and open-cast mines. The hole is charged at the rate of 2 to 3 oz
(57 to 85 g) of explosive per yd3 (74.2 to 111.3 g/m3 )
of rock. The charge is pushed to the bottom of the hole and then filled
with sand or soil. Also called pop shooting. See also:snakeholing
Nelson
Red orbicular jasper from California; popular for cutting en cabochon.
A method of drilling a hole just beyond the center of a boulder to be
broken so that the charge is centrally situated. Stemming is used.
Pop-shooting is economical in explosives, but drilling is required. It is
somewhat difficult to control the throw of broken material, but there is
little noise to cause annoyance to nearby property owners.
See also:secondary blasting
a. In mining, a shot fired for trimming purposes. BS, 12
b. In quarrying, a method of secondary blasting. BS, 12
c. A shot by which a boulder in a mine is broken up by placing a stick of
dynamite on top of the boulder and exploding it. Ricketts
d. In blasting, an explosion of the charge that simply blows out the
tamping. Syn:block hole shot
A pressure-relief valve. Long
A clay suitable for use in the manufacture of porcelain; specif. kaolin.
AGI
See:kaolinite
A hard, naturally baked, impure clay or porcellanite that, because of its
red color, was long considered a variety of jasper.
See also:porcellanite
A firing kiln used in baking porcelain. Fay
Resembling unglazed porcelain; e.g., said of a rock consisting of chert
and carbonate impurities or of clay and opaline silica. Also spelled:
porcellaneous; porcelanous. AGI
A dense siliceous rock having the texture, dull luster, hardness,
conchoidal fracture, and general appearance of unglazed porcelain; it is
less hard, dense, and vitreous than chert. The term has been used for: an
impure chert, in part argillaceous; an indurated or baked clay or shale
often found in the roof or floor of a burned-out coal seam; and a
fine-grained, acidic tuff compacted by secondary silica. Etymol: Italian
porcellana, porcelain. Also spelled: porcelanite; porcelainite.
See also:siliceous shale; porcelain jasper; haelleflinta. AGI
A space in rock or soil not occupied by solid mineral matter.
Syn:interstice; void.
See:neutral stress
The open spaces or voids in a rock taken collectively.
See also:porosity; permeability.
The deposition of minerals in the voids of rocks or between the grains of
loose sediment. Nelson
a. In soil technology, free water present in a soil. Normally under
hydrostatic pressure. The shear strength of adjacent soil depends on this
pore pressure, which reduces frictional resistance and soil stability.
b. Subsurface water in the voids of a rock. Syn:interstitial water