The following is a list of some different minerals Sites. Some of these sites are open for public rockhounding and other are private mining claims or are situated on a restricted public country where any form of mineral collection is forbidden.
Friday, November 12, Sign in. Forgot your password? Get help. Password recovery. Geology Page. Home Latest News Video. Debris Flow Dynamics. Sampling Hot Molten Lava. Fire Agate is a natural precious gemstone with deposits found only in certain areas of northern Mexico and the southwestern United States primarily Arizona, California, and parts of New Mexico.
These fire agate gemstone deposits fall within two general locations. The first, the Sonoran Desert region, stretches from the southwestern United States to northern Mexico. Fire agate gemstone deposits were formed in these particular regions approximately million years ago when the areas were subjected to massive volcanic activity during the Tertiary Period.
These hemispherical features are a characteristic crystal habit of agate known as a "botryoidal habit". Fire agate is a phenomenal gem.
In gemology, a phenomenal gem is one that reacts with the light that enters it to produce an interesting optical effect. In fire agate, the phenomenon is the iridescent colors. They change as the gem is moved, as the light source is moved, or as the head of the observer is moved. The phenomenon of fire agate is reminiscent of the play-of-color of precious opal , yet it is completely different. The name "fire" is used, but the color is not caused by dispersion - the phenomenon that causes the "fire" seen in diamond.
In fire agate, the botryoidal habit was built as many ultra-thin layers of agate were deposited, one upon another, to produce the unusual shapes that you see in the gem today. Some of these layers of ultra-thin agate were coated with tiny particles of goethite, an iron hydroxide mineral.
The colorful "fire" is thought to be produced by interference between light rays as they are reflected and refracted by the ultra-thin layers composed of goethite and agate. Arizona Fire Agate: This cabochon has botryoidal hemispheres which are much larger than those in the specimen at the top of this page. As a result, it is a thicker cab. This specimen measures 9 mm x 12 mm and weighs over 4 carats. Fire agate is not a widely known gem. This is because it is a rare material that has never been heavily promoted to the public.
Each stone cut from fire agate is different.
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