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.
Means having no definite form.
An opal, black or very dark only found in Australia.
A style of cutting opals, also a gem or bead cut in convex form and highly polished but not faceted.
cracks on the surface. looks like crazy paving, hence the name.
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.
Composed of or resembling crystals.
Opal value is measured as 'direction'.
is the method of fixing an opal to a wooden stick using adhesive wax in order to polish it.
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.
Mexican opals are called fire opals. They look more like crystal gems such as rubies than opals but are still opals nevertheless.
relates to the heat inside the earth. Geo meaning earth and thermal relating to heat.
This is the scale of hardness upon which all gems are measured. Diamond being the hardest and talc the softest.
Rarely one can find an opal formed from the remains of organic matter. This is call an organic opal.
Potch is the crusty mineral coating sometimes found on on naturally occurring opals.
Quartz is a silica mineral used in industry and for making glass for deep sea diving. It is a naturally occuring mineral.
Another mineral naturally occurring in great abundance on and in the earth.
A man made opal.
A Triplet opal is a manufactured opal made up of three layers of quartz, opal and obsidian.
The most common form of opal, Even though it is classed white it can be cream or milky in colour with a beautiful translucence.