Kyanite and lapis lazuli are two stones with a rich blue coloration.
However, due to this shared coloring, they can often be mistaken for each other.
Here is how you can tell them apart.
Kyanite vs Lapis Lazuli: The Basics
What is Kyanite?
Kyanite is commonly found in metamorphic rocks, and it is formed during periods of intense pressure that alter clay minerals during the metamorphic process.
Kyanite is typically seen as a bladed crystal, although it can also appear as a mass of crystals.
One unique property that kyanite possesses is an unusual varying hardness.
The long crystals of kyanite have a Mohs rating of around 4.5 to 5.0 if the hardness is tested parallel along the length of the crystal.
However, if tested access the short surface of the crystal, its hardness is around 6.5 to 7.0.
Because of the variation in hardness, kyanite was previously known as disthene, which means roughly “two strengths”.
Because of this strength variation, kyanite is rarely used as a gemstone, although some artisans or mineral dealers will offer kyanite cabochons.
It takes skill and special knowledge to understand how to cut this mineral so that it isn’t ruined.
While kyanite is usually found in blue, it can also appear in black, white, grey, pink, and rarely, purple, yellow, and green.
Orange kyanite has even recently been found in Tanzania.
The most popular types of kyanite are those with a deep blue hue.
However, lighter blue kyanite with a lower intensity of color can even resemble aquamarine or blue topaz.
Kyanite is found in many places across the world, with major deposits existing in Brazil, Russia, Switzerland, Tanzania, and the United States.
The Uses of Kyanite
Outside of use as a decorative piece, kyanite has a lot of uses in industrial products.
Calcined kyanite, known as mullite, is used to create clutch facings and brake shoes due to its high resistance to heat.
It is also used in some common forms of porcelain, such as those that make bathroom fixtures, sinks, and even dentures.
Its hardness and heat resistance also make it great for use in abrasive products like grinding wheels, where it is used as a binding agent to hold the shape of the wheel.
Some believers use kyanite for its metaphysical attributes as well.
What is Lapis Lazuli?
Lapis lazuli is a metamorphic rock that is often used as a gemstone, color pigment, and ornamental material.
Unlike most other stones used as gems, lapis lazuli isn’t a mineral.
It is instead composed of multiple minerals that fuse together during the metamorphic process.
For instance, the blue color that lapis lazuli is often associated with comes mainly from lazurite, a blue silicate.
Lapis lazuli is formed in limestone or marble that has been altered by either hydro or contact metamorphism.
In these conditions, lazurite replaces portions of the limestone or marble and often develops in layers or bands.
In order for a stone to be called lapis lazuli, it must be made up of at least 25% blue lazurite and have a distinct blue color.
Along with lazurite, calcite is often the second most abundant material found in lapis lazuli and it can give the appearance of white bands or mottling throughout the stone.
Pyrite can also occur in lapis lazuli, and it can usually be seen as tiny gold flecks across the stone or in layers or patches.
As a gemstone, lapis lazuli is often cut into cabochons or beads.
Pieces with a deeper blue color are the most desirable, with mottling or streaking quickly lowering their desirability.
However, because it only has a Mohs hardness rating of about 5.0, it can be too soft for use in rings or bracelets, as it can easily be scratched.
As a gemstone, lapis lazuli is best used in settings where it won’t face abrasions, such as earrings or pendants.
If you are storing loose lapis lazuli gemstones, you should keep them separated from each other and other stones to prevent damage.
Today, Afghanistan leads the world in lapis lazuli production, and some parts of the country have even been mined for this mineral for thousands of years.
Other countries with lapis lazuli deposits include Russia, Canada, Pakistan, and Argentina.
Some lapis lazuli has been found in the United States, mainly in Colorado, Arizona, and California. However, the amounts are fairly small.
The Uses of Lapis Lazuli
Lapis lazuli has been used a lot throughout history, both as a gem and as a pigment.
When used as a color agent, the blue parts of the stone are trimmed to remove impurities and ground them into a fine powder.
This powder can then be mixed with oil and used as a pigment.
The color ‘ultramarine blue’ came about once the refining process of removing impurities from lapis pigment had been perfected using a mild acid to remove lingering calcite.
This purified color was in use from the Renaissance until the 1800s.
While some artists — mainly those working in restoration or with specific historical techniques — still use this pigment today, it is costly.
A single pound of this pigment can go for over $1,000.
A few of the most well-known paintings using lapis pigment include The Starry Night by Vincent Van Gogh and Girl with a Pearl Earring by Johannes Vermeer.
Kyanite and Lapis Lazuli: Telling Them Apart
When it comes to telling kyanite from lapis lazuli, there are a few key things to remember.
Kyanite has a vitreous or pearly luster, and lapis lazuli has a dull to bright luster.
Kyanite is also found in a variety of colors, whereas lapis lazuli is blue with veins or mottling of calcite or pyrite.
Kyanite also has perfect cleavage in two directions, while lapis lazuli has none.
If using a streak test, kyanite will produce a clear or white streak, and lapis lazuli will produce a blue streak.
All of these differences make it easy to tell these two stones apart from one another.
Two Beautiful Blue Stones
Both kyanite and lapis lazuli are fascinatingly great stones and while they both can share a rich blue color, they are very different.
By knowing these differences, and what makes up each stone, you can start to more easily identify them for your own collection.