See:yttrium garnet
A discredited mineral name for an amorphous mixture of calcium sulfate,
tantalite, and heterogeneous microlite.
See:allanite
An orthorhombic mineral, (Y,U,Fe) (Ta,Nb)O4 ; radioactive; black to
brown: in pegmatites.
A monoclinic mineral, YW2 O6 (OH)3 .
Syn:thorotungstite
A monoclinic mineral, CaAl2 Si6 O16 .4H2 O ;
zeolite group; colorless to white; in low-grade metamorphosed tuffs near
the Yugawara hot spring, Kanagawa, Japan.
a. A noncrystalline mineral: Ca2 Fe3 (AsO4 )4
OH.12H2 O. AGI
b. An obsolete term originally assigned to an igneous rock intermediate in
composition between a tonalite and an aplite. It is named after the Yukon
River, Alaska. AGI
Mixed arsenates and oxides of cobalt produced by roasting sulfide ores.
Pryor, 3
Amorphous cadmium sulfide; greenockite is the crystalline form.
Am. Mineral., 1
An isometric mineral, Ni3 (CO3 )(OH)4 .4H2 O ;
emerald green; forms incrustations and compact masses in mafic and
ultramafic rocks.
See:zarnich
Native sulfide of arsenic, including sandarac and orpiment. Syn:zarnec
Webster 2nd
A tetragonal mineral, BiOF ; at Sherlova Gory, East Transbaikal, Russia.
a. One of the three optic axis (x, y, and z) in a biaxial crystal. The
z-axis is the axis of least ease of vibration. Light vibrating parallel to
the z-axis travels with minimum velocity and is called the slow ray, the
z-ray, and the gamma -ray. The highest index of refraction ngamma
, in biaxial minerals is the index of the slow ray vibrating parallel to
the z-axis.
b. One of three axes in a three-dimensional coordinate system.
Crystallographers customarily use a right-handed system with the z-axis
oriented positive upward, the y-axis positive to the right, and the x-axis
positive toward the viewer. For mineral parameters, the z-axis is labelled
c with periodic translations t3 . If one crystallographic axis is
symmetrically unique, it is labelled z, except in the monoclinic system,
where mineralogic convention uses the second setting labelling the unique
diad y.
One of the three coordinates in a three-dimensional rectangular coordinate
system. Webster 3rd
One of three orthogonal optic directions in biaxial crystals. Light with
its electric vector (vibration direction in early terminology) parallel to
the z-direction has the highest refractive index (ngamma ) for a
given crystal and is called the slow ray. In orthorhombic crystals, the
z-direction is constrained by symmetry to correspond to one of the
crystallographic directions, the correspondence determined empirically. In
monoclinic crystals, one optic direction, commonly the y-direction, is
constrained by symmetry to correspond to the unique diad. In triclinic
crystals, there is no symmetrical constraint relating optic directions to
crystallographic axes.
Wood opal, formerly a name for fire opal.
A term used in the Leadville district of Colorado for an altered dolomite
rock that shows conspicuous banding (generally parallel to bedding)
consisting of light-gray coarsely textured layers alternating with darker
finely textured layers. See also:zebra rock
a. A term used in the Colville district of NE Washington State for a
dolomite that shows narrow banding consisting of black layers (indicative
of organic matter) alternating with white, slightly coarse-grained, and
somewhat vuggy layers. See also:zebra dolomite
b. A term used in Western Australia for a banded quartzose rock of
Cambrian age. AGI
A portable dust-sampling instrument. See also:konimeter
A long-hearth reverberatory furnace used at Iola, KS. Fay