In our next instalment of A-Z Gemstones Uncovered, we will be taking a look at the "Mexican sunset captured in a gem" otherwise known as Fire Opal. A stunning stone, born from fire with colours so vivid and refractions that look too good to be true.
Instead of starting by delving into the history of this beautiful stone, I thought I'd dive into a question commonly asked - what are Fire Opals?
There is a lot of confusion around Fire Opals, with many people believing they are standard Opals, displaying a large variety of orange and red 'flashes'. However, Fire Opals are very different compared to standard Opals. Standard Opals tend to be opaque, white and carry what's known as 'opalescence'. This effect gives these gems their beautiful pastel glow of various colours. The distribution of these colours are random, varying from stone to stone, with the base colour always staying solid. Alternatively, Fire Opals are a transparent/translucent stone that varies from a butterscotch colour to orange. Fire Opals can exhibit a phenomenon known as 'play of colour'. Stones that have this are known as Precious Fire Opals, which show off refractions of vivid colours in both the 'fiery' tones and in greens/blues - these stones are rare and highly prized. More commonly found are Fire Opals which exhibit a single colour with a translucent, jelly-like quality. Sometimes these are called Jelly Opals however this name isn't exclusive to Fire Opals.
Now let's take it back to the beginning of these fiery gems...
Before the Spanish reached "The New World" otherwise known as present-day Mexico and Central America, Fire Opals were relatively unknown to the rest of the world. Until the "discovery" of these new Opals, the European gemstone market consisted of a small supply of Opals from Hungary.
Once the conquistadors looted the rich cities of the New World during the 16th Century, they uncovered this unique stone. Opal historian Allan W. Eckert suggested in his book, The World of Opals, that Hernando Cortez was the first one to bring Fire Opals to Europe during his expeditions. It is now believed a lot of the historical sources and artefacts from the Aztecs and ingenious people of Central America was destroyed by the conquistadors.
After the "rediscovery" of Fire Opals, their forgotten history began to uncover. These stones were frequently used by the Aztecs within their culture and rituals as early as 850 A.D. They were discovered in Aztec burial sites, figurines, inlaid in art and often worn in jewellery. In their native tongue, these Opals were, referred to as "vitzitziltecpatl" meaning hummingbird stone. The Opals, which exhibited the beautiful 'play of colours' were named "quetza-litzle-pyollili" by the Aztecs, which translates to 'stone that changes colour with the light'.
In other parts of the world, these Opals are, thought to have been around longer. As indicated by archaeological discoveries, historians believed Opals were first mined in East Africa around the Bronze Age (3100 BCE – 300 BCE). Some regions of modern-day Ethiopia are reportedly the earliest mining locations for Fire Opals and currently remain an abundant depositary.
So how are Fire Opals formed?
Staying true to its name, Fire Opals are born from fire (just like Khaleesi with her dragon babies). These Opals are said to form in the depths of extinct volcanoes. When water seeps into silica-enriched lava, it fills the seams and hollow areas. Under the right conditions of heat and pressure, the lava traps the water within itself, forming these fiery bright, magical stones.
Most of the Fire Opal mines in Mexico are open cast (mined from the Earths surface) high up in mountainous areas. However, Fire Opals also tend to be in crevices/cavities within these regions, here they are located within long, winding, narrow passages. In these cases, the sides of the rock face are over 50 metres high. These stones can be found in any rock fissures but are most commonly found in limonite, sandstone, rhyolite, marl, and basalt.
Specific to Mexico is another kind of Opal called Cantera Opals. Cantera means 'quarry'. These are Fire Opals cut into their rhyolitic host material. This option is chosen when it is too difficult to remove the Fire Opal from the rhyolite stone without damage. The stone is cut with a Fire Opal "window" which has become popular.
Due to their makeup, Fire Opals are extremely fragile and suffer from changes in humidity, temperature and light. Opals contain up to 20% water which means they can get dry out and crack; this is a phenomenon known as "crazing". Supposedly, this can be avoided by soaking Opals in water occasionally for a couple of hours. A lot of the time Opals are filled with oil, wax or plastic to avoid crazing - this can only be done during the lapidary process otherwise these oils/chemicals can ruin the stone.
Where are Fire Opals found?
Many Fire Opals are commonly known as Mexican Fire Opals. For nearly 100 years, Mexico has been the world's primary source of these stones. The most significant deposits were discovered in 1835 in Queretaro and are still producing today. These stones are also found in the Mexican states of Hidalgo, Guerrero, Michoacan, Julisio, Chihuahu and San Luis Potosi.
In 1990, Ethiopia became an important source of Fire Opals (arguably they are the world's oldest source of Opals). Again these depositaries are still producing today. Fire Opals from here tend to be more yellow.
Other sources of Fire Opal are produced in Australia, Brazil, Honduras, Guatemala and the United States (particularly in Nevada and Oregon).
5 fun facts about Fire Opals:
The most significant meaning of this stone is the joy of the heart. Fire Opals symbolises passion and a love for all things.
Orange and yellow stones are more common and as a result, are cheaper. The most valuable colour is red as it's the rarest amongst all hues. However, the more intense the hue is, the more valuable the stone is, regardless of the colour. The best stones per carat can even rival the most expensive Diamonds, Rubies and Emeralds.
Fire opal looks best when viewed in daylight just after sunrise or before sunset. This lighting exposes and maximises its intense colours.
Fire Opals is the only natural Opal that is cut faceted with precise calibration.
Indigenous people of Central America believed Fire Opal was a stone filled with life and created in heavenly waters. The Aztecs considered the stone a charm to protect against the evil eye and curses.
If you enjoyed this post, check out the rest in our series: A-Z Gemstone's Uncovered.
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