Found only in a few locations in the southwestern United States and Mexico, fire agate is a very thin layered golden brown to reddish brown agate with a botryoidal shaped layered structure.
A botryoid texture or mineral habit, also known as a mamillary or kidney texture, is one in which the mineral has an external shape made up of many rounded segments, named after the ancient Greek botrys, which means "bunch of grapes".
Each of the individual layers of fire agate is coated with the iron hydroxide mineral goethite, which provides the brown color.
What makes fire agate so amazingly beautiful is that the ultra-thin coatings of goethite evoke multi-color iridescence, mostly in red, golden orange and green, but sometimes in purple and blue.
Top quality fire agates can rival Australian black opal. Because they are a form of chalcedony quartz, fire agate is also more durable than opal, making it suitable for jewelry making.
