Labradorite and opal….you may have heard of the beautiful rainbow colors emitted by labradorites or the warm and soft play of color emitted by opals.
But people often confuse these stones.
In this article, we’ll help you learn about these stones so you can tell the difference.
Labradorite vs Opal: The Facts
What is Labradorite?
Labradorite is a mineral that contains all-aluminum silicates of the alkali metals barium, potassium, sodium, and calcium.
Labradorite ((Ca, Na) (AI, Si)4O8) displays an iridescent effect and was first identified in Canada’s Labrador region.
Labradorite is popular due to the Schiller effect in some specimens.
They produce an intense glow of yellow, red, blue, orange, and green colors.
This phenomenon is known as labradorescence, and only those that exhibit high qualities of this characteristic are used as gemstones.
Labradorite Occurrence
Labradorite occurs in the plagioclase series of mafic igneous rocks, for example, norite, basalt, and gabbro.
Sometimes labradorite is the most abundant mineral in igneous and anorthosite rocks.
Labradorite is formed in abundant, widely distributed banded or veined metamorphic rocks.
You can also find labradorite in sedimentary rocks resulting from weathering of other labradorite-containing rocks.
Properties of Labradorite
Labradorite belongs to the plagioclase series only that it exhibits labradorescence, unlike other rocks in the series.
Therefore, it will exhibit similar characteristics associated with this series.
With a Mohs hardness of 6-6.5, labradorite has a cleavage formed by the intersection of two planes at 90° to form triclinic crystals.
Labradorite can go in water, as it has a hardness level of above 6, though we don’t recommend it due to ever present risk of damaging the beautiful appearance of the stone.
Labradorite is not particularly toxic either, which is another reason it is a favorite among beginner collectors.
Labradorite has a vitreous to pearly luster on cleavages, transparent or translucent diaphaneity with white streaks.
It is hard to distinguish labradorite from other minerals in the plagioclase series if you don’t see the distinct shades of yellow, greenish, gray-white, pale green, and gray hues.
In this case, gemologists employ specific gravity determinations, x-ray diffraction, optical test, and chemical analysis to identify pure specimens.
What Causes Labradorescence?
What causes labradorescence, that colorful phenomenon that keeps most people’s eyes glued to the stone?
Contrary to popular belief, the display of color is not a surface occurrence; that is, light is not reflected from the stone’s surface.
Light infiltrates the stone and lands on the twinning surfaces inside the stone.
What you see is a twinning surface reflection from inside the rock.
The surfaces cause the color variety as each twinning surface produces a different color which gives the labradorite the famous multi-color appearance
Labradorite as a Gemstone
Although labradorites can be used for lapidary purposes, there is a whole controversy surrounding this.
Labradorite typically breaks in double directions to form a perfect cleavage; therefore, much care is required during cutting.
This character is disadvantageous because it makes the minerals prone to constant breakage on impact, making it a poor candidate for jewelry.
Added to that, labradorite has a Mohs hardness of 6, meaning that it can be scratched by jasper, diamond, agate, sapphire, diamond, emeralds, and rubies.
You will therefore have to store it separately.
Despite the controversy, labradorite has endeared itself to many due to the unique iridescent color display in some specimens.
This play of color, quality, and brilliance may occur within a single sample or vary from one rock to another.
Labradorite stones that exhibit top quality and unique play of color are known as spectrolites.
Common jewelers do not widely use labradorite due to its fragile nature.
You will rarely see any stone of this nature in mass-merchant jewelry.
Instead, seasoned designers and embroiders use labradorite for customized and unique projects.
Those specimens lacking labradorescence can still make beautiful gems if they produce aventurescence or other desirable colors.
Cutting Labradorite
Jewelers cut labradorescent material in a convex manner then polish them to produce cabochons.
The result is a jewel with a rounded base with a flat reverse.
What is Opal?
Opal is a variety of mineral silica that doesn’t form crystals.
Silica is the most abundant mineral on the earth’s surface, with varieties such as agate and quartz.
Opal chemical formula is SiO2H2O, meaning it is a mixture of silicon dioxide and water.
Surprisingly, this prehistoric rock may contain up to 30% of water in volume!
Opal is a mineraloid, meaning it has similar characteristics to minerals, but it isn’t a mineral.
Opal has Mohs hardness of 6.0-6.5, similar to that of quartz.
The rock is amorphous, meaning it doesn’t have any particular shape; hence each gem is unique.
Instead of crystals, opal is made up of tightly packed 0.00001inche silica spheres.
Here is a fun fact…Most opals were formed during the crutaceous period present when dinosaurs still roamed the earth.
Since opals contain water, they carry a portion of those great ancient oceans!
Formation of Opal
Opal occurs in volcanic rocks where ancient geothermal springs once existed.
As the hot water bubbled on volcanic rocks, they deposited silica oxide-rich deposits on the rock surfaces.
These deposits formed a lining on the walls or cavities of the bedrock, which have been drying for millions of years.
Did you know that it takes approximately five million years for a centimeter of opal to solidify?
Opals deposits occur in cavities of decaying vegetation, bones, and wood.
Southern Australia produces 90% of the world’s quality opal gems and rarest black opal gems exclusively.
Opals also occur in Ethiopia, Mexico, Nevada, and Brazil.
Opal Color
Opals are a combination or a blend of red, white, blue, and black colors in a harmonious all-in-one play of color.
In theory, opal is supposed to be colorless, but that rarely occurs.
Other minerals get deposited together with silicon dioxide, thus giving some opals a dull, bland appearance.
Most opals are common and don’t have any value.
Opals can display all these colors simultaneously, so the current gem color depends on the angle from which you’re viewing the gem.
Opals display a colorful color spectrum due to the interference and diffraction of light while passing through the rock.
To give you a more realistic look, think of light shining off a drop of water on a leaf in rainbow colors.
The ability of opals to refract and reflect various wavelengths of light is known as opalescence.
This unique blend of different color wavelengths makes opals one of the most sought-after gemstones.
Opal Varieties
There are two varieties of opal-precious and potch opal.
Precious opals are very rare and exhibit a dazzling blend of colorful colors.
Potch is the valueless dull variety widespread on the earth’s surface.
Here is a picture of the scarcity of precious opals: out of the opals mined, only 5% has some color, and only 0.25% has some value.
Labradorite vs Opal Similarities
Luster-both labradorite and opal have a pearly and vitreous luster, and opal is often confused with moonstone.
Hardness-both labradorite and opals have a hardness of 6.0 to 6.5 on the Mohs hardness scale.
Iridescence- both opals and labradorites refract and reflect various wavelengths of light to produce a play of colors of the rainbow.
The terms opalescence and labradorescence are used, respectively.
Labradorite vs Opal differences
Although both contain silica, their structures are different. Labradorite contains alkalis such as calcium, sodium, and aluminum. ((Ca, Na) (AI, Si)4O8)
Opal is a mixture of silicon oxide and water. (SiO2H2O)
Labradorite forms crystals in triclinic structures, while opals don’t form crystals at all. Instead, they contain silica spheres tightly packed together.
Color- Although both labradorites and opals have a playful color display, labradorites tend to have various distinct stripes of color due to the difference in reflection by the twinning surfaces.
Opals also feature colors of the rainbow in random speckles.
How To Tell The Difference Between Labradorite and Opal?
Labradorite and opal are very different elements, although they have similarities in hardness and colors.
People confuse the two because of the fact that both stones are beautiful because of the way the light is reflected.
Labradorite’s color is the result of light reflecting off the surfaces inside the stone, while opal’s color is the result of light refracting off the surface.
When you turn labradorite to the side, the color will change, or many even look gray from one angle, while it is bright and beautiful from another.
Opal might change colors are you turn it over or around, but that is because there are different colors in those surface areas that the light is bouncing off.
Wrap Up
Interested in learning more about unique rocks and minerals like hag stones, stilbite, tanzanite, or velvet malachite? You can also check out our blog for our latest articles.
