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Agate (a variety of Chalcedony)
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Discovered between the 4th and 3rd centuries BC; IMA status: Not Valid (variety of Chalcedony)
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More
Information
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Agate
is a variety of Chalcedony;
Quartz. For more information please
see the Chalcedony
and Quartz
information pages. |
Varieties: |
Abakusz-kö,
Agate-Jasper, Blue Lace Agate, Botswana Agate, Brecciated Agate,
Cloud Agate, Crazy Lace Agate, Dendritic Agate,
Enhydro Agate, Eye Agate,
Fairburn Agate, Fortification Agate, Fossil Agate, Haema-ovoid-agates,
Herbeckite, Iris Agate, Laguna Agate, Lake Superior Agate,
Mexican Lace Agate, Mocha Stone, Nipomo Agate, Onyx,
Pigeon Blood Agate, Plume Agate, Riband Agate, Sardonyx,
Schlangenhautachat, Snakeskin Agate, Vogelaugenachat,
Youngite (many other names based on colors, locations
and patterns)
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Synonyms: |
Achates,
Oriental Agate
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Additional
Information: |
Mindat.org
(Agate) Mindat.org
(Chalcedony) Mindat.org
(Quartz) Webmineral.com
(Quartz)
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View
mineral photos: |
Agate
Mineral Photos and Locations |
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Agate
was named for the Achates River, Acate, Ragusa Province,
Sicily, Italy by Theophrastus, a Greek philosopher and naturalist, who discovered the stone along the shore of the river Achates sometime between the 4th and 3rd centuries BC.
This river is now called the Dirillo river and colorful Agates and other Chalcedonies can
still be found there.
Agate
is a distinctly banded variety of Chalcedony
which is a variety of Quartz.
Chalcedony is
a translucent variety of cryptocrystaline,
or fine-grained, Quartz
with a fibrous microstructure. Agate is characterised
by its concentric (having the same center
or axis) banding which may be fairly simple
or wildly patterned and often brightly colored by many
different types of impurities. Agate has many variety
names based
on colors, locations and patterns. Some of the most
common varieties are Blue Lace Agate, Botswana Agate,
Brecciated Agate, Crazy Lace Agate, Fairburn Agate,
Fortification Agate, Laguna Agate, Lake Superior Agate,
Mexican Lace Agate, Nipomo Agate, Pigeon Blood Agate
and Plume Agate.
Chalcedony
includes many subvarieties such as the many varieties
of Agate, Binghamite,
Bloodstone, Carnelian, Chrysoprase, Onyx, Pietersite,
Petrified
Wood, Sard and Sardonyx. When Chalcedony is concentrically
banded it is called
by the subvariety name Agate. When it is in flat layers
or bands of black and white, it is called by the subvariety name Onyx.
When it is in flat layers
or bands of light and dark shades of reds, browns and
white, it is called by the subvariety name Sardonyx.
Many non-banded forms of Chalcedony - such
as Moss Agate, are
often erroneously called 'Agates'. True Agate is concentrically banded. Mottled
and included Chalcedonies are more properly simply called 'Chalcedony.' Petrified
Wood (agatized
wood) is the name given to fossil wood where the replacement of the wood is by
Chalcedony, but the banding in this case is due to the wood structure or growth
rings - not
concentric deposition of the Chalcedony - and the material is Chalcedony, not
true Agate.
Agate
is
available from many sources worldwide.
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Agate
gems for sale:
We
have not photographed our Agate
gems. Please
check back soon.
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