Opal is a gemstone that stands out due to its distinctive iridescent shine. It belongs to a unique category all its own and is so distinctive that it even has its own vocabulary for describing itself.
It is understandable that opal has long been thought to have supernatural powers given the mesmerizing rainbow-like colors that dance and play across its surface.
Opals stand out among their peers in every way. As a species, opal is so unique it has its own descriptive vocabulary. Each opal is uniquely different from every other gem, by far.
Given its priceless spiritual and aesthetic qualities, opal has been prized since the dawn of time. Different types of Opal stones are a stunning choice for high-end jewelry because a gold or diamond setting brings out the riot of colors that reside inside this stone.
However, the versatility of opal means it may also create a basic yet attractive everyday accessory. A unique and alluring look can be created with sparkling bead bracelets and tiny crystal necklaces.
Table of Contents
What are Opal Stones?
The glistening milky to the pearly iridescence of opal, a translucent to transparent semi-precious gemstone, has mesmerized jewelry lovers for centuries.
Opal is a popular birthstone for October and an opalescent stone belonging to the silica mineral family, which also includes quartz and cristobalite.
Opal is known for its unusual shimmering and changing colors that range from ivory white to pearly pink or pale blue as the stone is moved in different directions. This phenomenon is brought on by the mysterious interaction of light within the stone’s crystalline fractures.
How do Opal Stones Form?
Sometimes, given the right circumstances, silica spheres from earth’s silica-rich fluids develop and settle under the force of gravity to form layers of silica spheres. The solution is thought to deposit at a rate of around one centimeter in thickness per five million years at a depth of forty meters.
Precious opal starts to form when the procedure enables spheres to grow to a uniform size. For opal deposition to occur, each local opal field or occurrence needed to have some kind of void or porosity.
Opal doesn’t seem to fill any spaces or fissures in volcanic rocks and the surrounding environment, but there are many voids in sedimentary rocks that have been left by weathering.
In addition to the pre-existing fissures, open centers of ironstone nodules, and horizontal seams, leaching of carbonate from boulders, nodules, and various fossils also creates a variety of moulds suitable for the deposition of secondary minerals such as opal.
The majority of the opal deposit is not priceless. The mineralogists refer to it as common opal since it lacks a color play, but the miners refer to it as “potch.”
Opaline silica not only fills the larger voids mentioned, but it may also fill the pore space in sediments of silt and sand size, binding the grains together and forming distinctive deposits, such as matrix, opalized sandstone, or “concrete,” which is a more conglomeratic unit close to the base of early Cretaceous sediments.
Numerous variables affect the numerous variances in opal varieties. A rising or, more significantly, falling water table that concentrates any silica in solution is caused by the climate’s alternating wet and dry seasons.
The silica itself is produced by extensive weathering of Cretaceous clay deposits, which also produces white kaolin, which is frequently found in association with the Australian opal fields.
In order to create the distinct environment necessary for the development of its own variety of opals, special circumstances must also exist to stop a declining water table.
However, some think that there must be acidic conditions at some point during the process to generate silica spheres, presumably caused by bacteria. The chemical conditions that produce opal are currently being explored.
What can I do with Opal Stones?
Opal stones can be used for a variety of things.
- Polishing Characteristics
- Additional Numerous Functions
95 percent of opals are utilized as gemstones in jewelry, decorations, and the collectors’ market. The colors and patterns of these opals are frequently admired.
Opals are sometimes used as a focal point during incantation rituals as well as in gemstone therapy. For instance, money rituals frequently involve the use of the fire opal. Opal is frequently referred to as the “queen of gems” and has long been prized.
Opals were seen as symbols of purity and hope by the Romans and foresight by the Greeks. They were regarded as divine talismans that could fend off illness and safeguard their owner from harm.
2. Polishing Characteristics
Tripoli and Fuller’s earth are other names for diatomaceous opal, which is an opal that contains diatoms. When working with metals, precious metals, and gemstones, this kind of opal is utilized as a fine powder abrasive. (including opals).
Tripoli, which is highly valued for its extremely fine abrasive properties, is also known as rottenstone due to its fragility. This tiny item is utilized in filtration systems and abrasive soaps as well.
3. Additional Numerous Functions
Opals are also used in brick, sewage pipe, ceramic, and refractory mixes, as well as as an absorbent component in medications, pharmaceuticals, and cosmetics, according to Eckert. Opal is also used as a component in insulation and fertilizers.
16 Types of Opal Stones
There are numerous varieties of opal, however, they can be divided into two categories: common opal (also known as potch) and precious opal. (also known as noble opal).
Unlike ordinary opal, precious opal has a play of spectral colors throughout the stone. Common opal can be any color, some of which are quite lovely, and is often opaque to translucent and brownish orange in hue.
Regardless of how they are categorized, we have only listed a small number of the many opal stones available, whether they are rare or common.
- Black Opal
- Boulder Opal
- Fire Opal
- Light Opal
- White Opal
- Crystal Opal
- Matrix Opal
- Peruvian Opal
- Pink Opal
- Cat’s-Eye Opal
- Blue Opal
- Morado Opal
- Synthetic opal
1. Black Opal
Without adding the famed Black Opal, which is often also known as the Australian black opal, no list of opals could ever be considered complete. One of the rarest and most valuable types of opal that are still found today is the black opal.
Contrary to popular belief, the naturally occurring black opal isn’t actually a stone that is entirely black. In contrast, the black opal typically has a black undertone.
The traditional play of colors pattern seen in all opals is present on a black background, making the black opal distinct from other types of opals.
This is sometimes described as having a “black body color.” A priceless Australian opal that is native to Lightning Ridge, South Australia, is the black opal.
2. Boulder Opal
Another type of an Australian opal stone that is primarily found in South Australia is the Boulder Opal. In the country’s Queensland region, it is typical.
Typically, this particular stone is not an opal gem that is entirely solid. It is actually a rock or stone covered in opal. The host rock (or boulder) that the Boulder Opal typically develops around ends up becoming a natural component of the gem.
In-fillings of fractures and gaps in the rock are how the opal manifests itself. This is particularly valid when referring to an ironstone boulder. Therefore, the majority of the gem is essentially the host rock, with the opal acting as a thin veil over the boulder.
Depending on how the host rock appears when seen from the surface, boulder opals can be either dark or dazzling in hue. Boulder opal is prone to cleaving as well. Two opal faces are left after the “split,” one of which is naturally polished and the other not.
3. Fire Opal
Since there are several different forms of fire opal that are indigenous to various parts of the world, the name “fire opal” often causes confusion among the public.
Because of this, even though the Austrian Fire Opal and the priceless opal are very distinct from one another, it is a common mistake to mix them up. A variety of opals with vivid hues like yellow, orange, and red is called a “Fire Opal.”
Fire opals are mostly discovered in Australia, however, they are also mined in Queretaro. These stones can also be discovered in Honduras and the United States of America, where it’s said to be common to find additional, more expensive types.
Contrarily, a Mexican fire opal is distinctive. The name “fire opal” refers to these delicate stones’ frequent transparency to translucent appearance in fiery hues.
Colorless opal having a glass-like appearance, hyalite is also referred to as Muller’s Glass. It does, occasionally, tend to show a subtle tint of blue, green, or yellow. Locally, water opal is the name given to the Mexican-origin hyalite variety.
These incredibly rare opals, which are famously found in Oregon and Mexico, are prized for their crystal-clear appearance.
The girasol opal, which is a variety of hyalite opal and has a bluish glow or sheen to it, is another variation of the water opal. This bluish sheen is able to move around in chase of the light source that illuminates it.
There have been two uses of the term “opalite.” The common opal without a play of color was its original application.
Opalite has been defined in geology and gemology glossaries for many years. In the 1980s, a plastic imitation opal with true play-of-color was marketed under the name “opalite.” Since then, this use has expanded to encompass a range of opalescent or plastic and glass materials that resemble opal.
6. Light Opal
The body of the Light opal is often light, translucent, or opaque and exhibits a vibrant display of colors. It can be further classified into opals with hues ranging from cream to white.
The opal will have a softer, more pastel appearance because of the milder undertones, and the color plays on the stone itself will be more subdued. Brazil, Australia, and Ethiopia are among the countries where light opals can be found.
7. White Opal
The white opal, one of the most prevalent varieties of opal, is sometimes referred to as “milk” or “milky opal.” The White Opal’s light body tone and capacity to display any color in the spectrum in a stunning array of hues are its defining features.
A “white potch,” or colorless opal, can also be found in white opals, especially on the stone’s backside. This is not always necessary, though.
Frequently, the white opal may be made up almost entirely of colorful opal. However, because there isn’t a black background, the colors in white opal are typically not extremely heightened or apparent.
8. Crystal Opal
Any opal with a transparent, translucent, or semi-translucent shine is referred described as a “crystal opal.” Observing whether light can travel through the stone is one simple technique to tell if it is a crystal opal.
The amount of light that can travel through the stone is one way to gauge its “diaphaneity.” The ability of crystal opals to reflect light in a stunningly brilliant show sets them apart from other gemstones.
However, boulder opals differ from crystal opals in that the latter has an opaque ironstone background. Compared to opals that are fully opaque, the Crystal Opal’s translucence makes it clearer and enables it to display colors in more vibrant patterns.
9. Matrix Opal
As its name suggests, the Matrix Opal, or Type 3 Opal, has a dense and close distribution of the priceless opal throughout the stone. Precious opal that is present between the sediment particles as a cementing agent may make up the host rock itself.
The play-of-color opal might appear as an infilling of the tiny vesicles in the host rock or as a replacement of the host material itself. The mixture that results resembles the host rock in appearance but continuously exhibits flashes of priceless opal that flashes from within.
When held up to a light source, a properly cut Matrix Opal will display a stunning array of internal color play. When looking at the stone, turning one’s head from side to side will also cause the priceless gem to sparkle in a lovely display.
However, the Matrix Opal must be carefully cut after a thorough examination of the rough rock. By doing so, the cutter will be able to comprehend the location of valuable jewels within the rock as well as the orientation that results from an incident light ray striking the stone.
The stone can then be carved in such a way that the stone’s beauty and grandeur are fully seen. The most common places to find Matrix Opal are in Australia, Mexico, and Honduras.
10. Peruvian Opal
Of course, the name alone provides sufficient clues. Originating in Peru, South America is where the Peruvian Opal was first discovered.
The actual stone itself is found in lovely, colorful pinks, greens, and blues. It is a translucent to opaque stone. The Peru opal is classified as a “common opal” because it lacks the distinctive play-of-color quality that is characteristic of precious opal.
Opal stone enthusiasts will never consider the hues to be common since they are too exquisite and distinctive. Common uses for Peruvian opals include beads, tumbled stones, and cabochons.
Although the semi-translucent kind may cost more than the basic, pastel-colored stones, Peruvian Opals are typically affordable.
11. Pink Opal
Pink hues can be observed in some varieties of opal. These so-called “pink opals” are typically mined in Peru and infrequently in some areas of Oregon.
The pink opal is often a little gemstone around four millimeters in length. Its color ranges from nearly white to brilliant pink and even violet.
Peru is the country where the pinkest opal is mined. However, the gem is also found in small but large quantities in other regions, such as Oregon. A “pink Mexican opal” is also a typical term for the lighter-hued rhyolite-hoisted fire opal from Mexico.
12. Cat’s-Eye Opal
Opal rarely exhibits chatoyancy, the optical phenomenon that causes a “cat’s eye” to appear on a stone’s surface. These opals have a parallel network of needle-shaped inclusions that reflect a thin line of dazzling light from the gem.
When the stone, the light source, or the observer’s head are moved, the line, or the “eye,” moves back and forth over the stone’s dome. A cat’s-eye opal from Madagascar is displayed here.
Hundreds of parallel rutile needles that cover the width of the stone and reflect a line of light that resembles the line of light reflected from the surface of a spool of silk thread are what give the stone its chatoyancy.
13. Blue Opal
Many people are startled to find that blue opal exists because they have never seen it. It is frequently carved into lovely beads and cabochons.
The most well-known sources of the highly prized blue common opal are in Peru, Oregon, and Indonesia.
The Oregon-mined Owyhee blue opal has a pastel blue hue that ranges from light to dark. Some Peruvian blue opal beads have tiny translucent zones with color play. Usually, opalized wood is related to the blue opal found in Indonesia.
14. Morado Opal
The Spanish word for “purple” is “Morado.” Mexico produces some common opals with purple body color. It is frequently referred to as “Morado Opal” or just “Morado.” There aren’t many places in the globe where you can find opal that is a deep purple tint.
15. Synthetic opal
Opals of all kinds have been created synthetically using both commercial and experimental means. In 1974, Pierre Gilson synthesized valuable opal after learning about its organized sphere structure.
By virtue of its regularity, the produced material may be distinguished from natural opal; when viewed up close, the color patches can be observed to be arranged in a “lizard skin” or “chicken wire” pattern.
Additionally, artificial opals do not fluoresce when exposed to ultraviolet light. Additionally, synthetic materials frequently have a lower density and are quite porous.
One of the unique, priceless stones mentioned in classical Greek mythology is the opal. They were known as “Opallios” by the Greeks, which means “color of change” in English.
Zeus’s happy tears after defeating the Titans were supposed to have transformed into these stunning opals. Opals can confer supernatural gifts and powers upon their wearers, which is another interesting fact about their past.
According to legend, certain kinds of opal were thought to have therapeutic properties in antiquity. This concept still holds true today, and it is the reason why many cultures consider opals to be lucky jewels.
How many types of opal are there?
Since there are so many opal stones available, putting a number on them would be difficult.
What color of opal is the most expensive?
The most uncommon and expensive variety of opal is black opal, which is distinguished by its “black” (or “dark”) body tone.
What is the most common type of opal?
The most popular opal stone worldwide is the white opal stone.
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