A general term for a line on a map or chart connecting points having an
equal numerical value of some physical quantity (such as temperature,
pressure, or rainfall); an isopleth. AGI
A line constructed on a map, somewhat similar to a contour line, but
connecting points of equal moisture content of coal in the bed.
AGI
A line connecting points of equal precipitation. AGI
A culture of an organism isolated by selection procedures. Rogoff
A particular case of a single consignment where the sampling is to be
carried out without prior knowledge of a coal's sampling characteristics
other than its presumed ash content and size. Nelson
Part of a circuit that can be removed from it in order to break the
circuit when there is no current flowing. Hammond
See:isopleth
a. An imaginary line connecting points of similar lithology and separating
rocks of differing nature, such as of color, texture, or composition.
AGI
b. An imaginary line of equal aggregate thickness of a given lithologic
facies or particular class of material within a formation, measured
perpendicular to the bedding at selected points (which may be on outcrops
or in the subsurface). AGI
A map that depicts isoliths; esp. a facies map showing the net thickness
of a single rock type or selected rock component in a given stratigraphic
unit. AGI
A line connecting points of equal value of some magnetic element; e.g.,
isogonic line; isodynamic line; isoporic line. AGI
a. One of two or more substances composed of the same molecular formula,
but differing in chemical or physical properties owing to the arrangement
of the atoms in the molecule. Hess
b. In nuclear science, one of two or more nuclides with the same numbers
of neutrons and protons in the nucleus, but having different energy.
Lyman
Of, relating to, or exhibiting isomerism. Webster 3rd
a. A system of crystallization with three axes at right angles and of
equal length; nine planes of symmetry; singly refracting.
CF:anisodesmic
b. Characterized by equality of measure.
c. The crystal system characterized by three orthogonal axes of equal
length. Syn:cubic; equant. CF:anisometric; isodiametric.
See:isopleth
In technical drawing, a three-dimensional view of an object can be drawn
to scale with three perpendicular edges at 120 degrees to each other, and
with the vertical edges vertical. See also:oblique projection;
axonometric projection. Hammond
The name given to chemical compounds that have analogous composition,
similar crystal structures, and closely related crystal forms; e.g.,
carbonate minerals of the aragonite group--aragonite, witherite,
strontianite, and cerrusite--in which the metal ions are different but the
several minerals crystallize in the orthorhombic system in closely similar
forms. Adj. isomorphous. Noun, isomorph. CF:polymorphism
Originally defined (Mitscherlich, 1819) as having similar crystalline
form, but now generally restricted to compounds that form solid solutions
by isomorphous substitution; i.e., by the replacement of one ion for
another in a crystal structure without alteration in the crystal form.
CF:isotypic
a. A solid solution of two or more isomorphous substances. Fay
b. A type of solid solution in which mineral compounds of analogous
chemical composition and closely related crystal habit crystallize
together in various proportions. CF:solid solution
Harbison-Walker
A characteristic of some minerals where substitution for one or more
elements by others does not change the crystal structure. An example is
the substitution of iron for zinc in sphalerite, wherein the iron content
can range up to more than 15% without changing the sphalerite structure.
Similarly, iron, manganese, and magnesium ions can replace each other in
the calcite structure common to siderite, rhodochrosite, and magnesite.
Descriptive of two minerals with the same crystal structure but different
end-member compositions which may show partial or complete crystal
miscibility (solid solution) between them. One mineral may belong to more
than one isomorphous series; e.g., the garnet grossular forms a series
with andradite, with hibschite and katoite, and with uvarovite. There are
many isomorphous series among minerals; e.g., plagioclase feldspars,
monoclinic pyroxenes, and the spinel and garnet groups.
CF:solid solution
See:isopleth