Color:
All colors are possible, whether naturally occurring or as the result of dying.

Durability:
Excellent. Agates are extremely tenacious.

Localities:
Found all over the world, abundantly.

Varieties:
Abakusz-kö
Agate-Jasper
Blue Lace Agate

Botswana Agate
Brecciated Agate
Cloud Agate

Crazy Lace Agate
Enhydro Agate
Eye Agate

Fire Agate
Fortification Agate
Fossil Agate

Haema-ovoid-agates
Iris Agate
Laguna Agate

Lake Superior Agate
Mexican Lace Agate
Nipomo Agate

Onyx
Pigeon Blood Agate
Plume Agate

Riband Agate
Sardonyx
Vogelaugenachat

Agate
SiO₂

Agate is a variety of banded microcrystalline quartz, or chalcedony. There are countless varieties of agate usually named after their physical characteristics or location of origin. The layers of agate form as layers of chalcedony line a cavity (or vug) in a host rock.
Since the twelfth century agate has been attributed with the power of improving one's disposition as well as their eyesight. These beliefs still carry on today. My favorite claims for agate were stated in The Book of Saxon Leechdoms written in 1864. Here, it was written, that agate prevents harm from thunder, sorcery, demonic possession, poison and drunkenness!

Quartz Family: Amethyst Citrine Ametrine Rutilated Quartz Smokey Quartz Rose Quartz Dendritic Quartz Tourmalinated Quartz Phantom Quartz

Microcrystalline Quartz: Agate Chrysoprase Jasper Carnelian Bloodstone Onyx

The Curious Lore of Precious Stones:
by George Frederick Kunz

Gemstone Buying Guide: A Guide to Buying
by Renee Newman