Opal Glossary
Agate
Agate is a term applied not to a distinct mineral species, but to an aggregate of various forms of silica, chiefly Chalcedony. It can be banded, striped, or mosslike coloration.
Amorphous
Means having no definite form.
Black Opal
An opal, black or very dark only found in Australia.
Cabochon
A style of cutting opals, also a gem or bead cut in convex form and highly polished but not faceted.
Crazing
cracks on the surface. looks like crazy paving, hence the name.
Crystal Opal
A crystal opal is very valuable due to the brilliance of color 'flashes' that can be seen within it. Many layers of color are visible within the opal.
Crystalline
Composed of or resembling crystals.
Direction
Opal value is measured as 'direction'.
Dopping
is the method of fixing an opal to a wooden stick using adhesive wax in order to polish it.
Doublet
this is an artificial opal created by join opal and obsidian or firtestone. Sometimes called a manufactured opal.
Fire (or pinfire)
The measure of color or iridescence of an opal.
Fire Opal
Mexican opals are called fire opals. They look more like crystal gems such as rubies than opals but are still opals nevertheless.
Geothermal
relates to the heat inside the earth. Geo meaning earth and thermal relating to heat.
Mohs' Scale
This is the scale of hardness upon which all gems are measured. Diamond being the hardest and talc the softest.
Organic Opal
Rarely one can find an opal formed from the remains of organic matter. This is call an organic opal.
Potch
Potch is the crusty mineral coating sometimes found on on naturally occurring opals.
Quartz
Quartz is a silica mineral used in industry and for making glass for deep sea diving. It is a naturally occuring mineral.
Silica
Another mineral naturally occurring in great abundance on and in the earth.
Synthetic Opal
A man made opal.
Triplet
A Triplet opal is a manufactured opal made up of three layers of quartz, opal and obsidian.
White Opal
The most common form of opal, Even though it is classed white it can be cream or milky in colour with a beautiful translucence.
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