An isometric mineral, 8[Fe2 TiO4 ] ; spinel group; in mafic
igneous rocks as fine exsolution lamellae in magnetite. Named for the
Ulvoe Islands, Sweden. Syn:ulvite
A tetragonal mineral, Cu3 Se2 ; dark red, tarnishing to
violet.
A plow developed from the Anbauhobel machine to allow the conversion of a
Lobbe Hobel to give the plow an independent drive. Nelson
A brown earth that is darker than ocher and sienna, consisting of iron
oxide and oxyhydroxide with manganese oxides, clay, and lime. Highly
valued as a permanent pigment, it may be used in its greenish brown
natural state (raw umber) or in the dark or reddish brown calcined state
(burnt umber). CF:ocher; sienna.
Protective hood over a hoisting cage in a mine shaft. Pryor, 3
A monoclinic and orthorhombic mineral, UO2 MoO4 .4H2
O ; black to blue-black; secondary; the only known uranium mineral to
contain molybdenum.
An assay made by a third party to settle a difference found in the results
of assays made by the purchaser and the seller of ore.
See also:control assay
Universal mill plate, or plate that is rolled to width by vertical rolls
as well as being rolled to thickness by horizontal rolls. Osborne
An epidote-rich granite, which also contains pink orthoclase, quartz, also
minor opaque oxides, apatite, and zircon. The name is derived from the
type locality, the Unaka Range, Great Smoky Mountains, in eastern
Tennessee. AGI
A cutter chain that carries more picks along the bottom line than the
topline. Most chains for cutting at floor level are unbalanced to assist
in keeping the jib down. See also:balanced cutter chain
The method of hoisting in small one-compartment shafts where only one cage
is in operation, as opposed to balanced winding. Nelson
A shothole in which the explosive charge breaks down the coal at the back
of the machine cut while leaving the front portion standing or in large
blocks. This may happen with a deep bottom cut in a thin seam where the
vertical distance from the explosive to the inner end of the cut is
shorter than the horizontal distance to the exposed face of the seam.
Nelson
To disengage the drill chuck from the drill stem. Long
Excavation paid for at a fixed price per yard, regardless of whether it is
earth or rock. Nichols, 1
unconfined compression appliance
A portable appliance for carrying out uniaxial compression tests at a
site. Syn:unrestrained compression apparatus
A special condition of a triaxial compression test in which no confining
pressure is applied. See also:triaxial compression test; crushing test.
AGI
unconfined compressive strength
The quality, state, or condition of being unconformable, such as the
relationship of unconformable strata; unconformity.
See also:unconformity
Said of strata or stratification exhibiting the relation of unconformity
to the older underlying rocks; not succeeding the underlying rocks in
immediate order of age or not fitting together with them as parts of a
continuous whole. In the strict sense, the term is applied to younger
strata that do not conform in position or that do not have the same dip
and strike as those of the immediately underlying rocks. Also, said of the
contact between unconformable rocks. CF:conformable
AGI
a. A substantial break or gap in the geologic record where a rock unit is
overlain by another that is not next in stratigraphic succession, such as
an interruption in the continuity of a depositional sequence of
sedimentary rocks or a break between eroded igneous rocks and younger
sedimentary strata. It results from a change that caused deposition to
cease for a considerable span of time, and it normally implies uplift and
erosion with loss of the previously formed record. AGI
b. The structural relationship between rock strata in contact,
characterized by a lack of continuity in deposition, and corresponding to
a period of nondeposition, weathering, or esp. erosion prior to the
deposition of the younger beds, and often marked by absence of parallelism
between the strata; strictly, the relationship where the younger overlying
stratum does not conform to the dip and strike of the older underlying
rocks, as shown specif. by an angular unconformity.
Syn:unconformability; transgression. AGI
Rocks consisting of loosely coherent or uncemented particles, whether
occurring at the surface or at depth.