What is Fire Agate?
Photo Credit: Glenn Dizon


Agate is a semi-precious gemstone formed by relatively recent volcanic activity. It is outwardly similar in appearance to quartz, but also shows interesting swirls, bubbles and patterns.

Fire agate, a variety of chalcedony, is a semi-precious natural gemstone discovered so far only in certain areas of central and northern Mexico and the southwestern United States (New Mexico, Arizona and California).

Fire agates have beautiful iridescent rainbow colors, similar to opal, with a measurement of hardness on the Mohs scale of between 5 and 7 which reduces the occurrence of scratching when polished gemstones are set in jewelry.



The vibrant iridescent rainbow colors found within fire agates, created by the Schiller effect as found in mother-of-pearl, is caused by the alternating silica and iron oxide layers which diffract and allow light to pass and form an interference of colors within the microstructure layering of the stone causing the fire effect for which it is named.

Photo: Isaac Jones

How Fire Agate and Chalcedony Form

The fire agate and chalcedony of the Southern New Mexico–Arizona border area is formed when low pressure and low temperature epithermal hydrothermal waters (50°-200°C / 122°-392°F) carrying colloidal SiO2 and iron oxides are injected into cavities in volcanic rocks such as gas bubbles in flow rocks, irregular-shaped vug fillings, or along fault or bedding plane fractures.



Approximately 24-36 million years ago these areas were subjected to massive volcanic activity during the Tertiary Period. The fire agates were formed during this period of volcanism when hot water, saturated with silica and iron oxide, repeatedly filled cracks and bubbles in the surrounding rock.

Fire Agate Gemstone Mineral Locations

Deer Creek, Arizona
Deer Creek Fire agate is well known for it's high quality fire agate gemstones and excellent lapidary rough. The fire agate from Deer Creek Arizona ranks high on the list of desired collected gemstones, mineral specimens, and lapidary gemstone cutting material. Located in the eastern foothills of the Galiuro Mountains southwest of Safford, Arizona, this area has several active fire agate mines. Some of the early pioneers in fire agate mining at Deer Creek were Larry Gray, Howard Imboden, Guy Paul and Cliff Willis.

Cuesta Fire Agate Mine - Arizona
Cuesta Fire Agate mine is a Desert Dig. when you come out to the Mine, you go to the claims and you can dig to your hearts content. without restrictions to what or where you can Dig. The Mine is open 12 months of the year.  fee: $30.00 - $50.00 a day, Tool Rentals, $5.00 a day.
Address:  old Route 66 4 miles north of Oatman, AZ.

Slaughter Mountain - Arizona
Known for it's high quality fire agate gemstones and with it's rough often having multiple layers of fire banding, Slaughter Mountain Fire Agate is well suited for gemstone carving purposes. The mine at Slaughter Mountain is known for producing high quality fire agate gemstones, with intense color variations from bright reds and oranges to intense greens, purples and blues.

See also:
What Is Grape Agate?
Tourmaline: Species and Color Varieties
Types of Iridescent Gemstones & Minerals
 
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