What Is the Texture of Turquoise and How Is It Formed?
Have you ever twirled a ring around on your finger, or held a pendant for a second longer than usual, and pondered the origins of its gem? Jewelry highlights, rather than depletes, the natural beauty of raw materials. However, the journey from the beginning of a gem’s life to its placement in your favorite necklace is not a short one - and it’s fascinating to discover!
Turquoise is best known for its brilliant blue coloring, its most valuable hue. The stone also comes in greenish tones and is beloved among Indigenous cultures worldwide. It has been mined everywhere from the southwestern United States to Persia, with Native American culture believing it to represent power and luxury.
A boom in popularity during the 1970s forced imitations and modifications of turquoise in the U.S to maintain a large enough supply.
Today, the December birthstone is a staple at Mark Henry Jewelry. Read on to learn more about how this unique gem is formed and how it makes its way from our mines to your closets.
A Storied Past
It would be impossible to pinpoint the first discovery of turquoise, as it has been used in jewelry and ornamentation in the earliest recollections of ancient civilizations. Egyptian turquoise has been mined in the Sinai Peninsula as far back as the First Dynasty, right around 3000 BCE.
The indigenous people of Monitu brought these gorgeous pieces to their people, who quickly understood their high value. In Iran, the gem has been mined for 2,000 years. In China it has been mined for 3,000 years, and in Bulgaria turquoise has circulated since the 5th millennium BCE.
In more modern times, turquoise mines began to pop up in the southwestern United States, namely throughout Arizona, California, Colorado, New Mexico, and Nevada. Gems found in Arizona have the purest blue colors and are typically the most expensive.
Turquoise is best formed in arid climates and has also been documented in Afghanistan, Australia, Northern India, Northern Chile, Cornwall, Saxony, Silesia, and Turkestan. It is important to note that each location has a different variation of turquoise.
Gems found in Egypt are derived from basalt-covered sandstone and are typically greener, more durable, and more stable than those found in Iran. Iranian turquoise first appears black and then turns green when heat produces dehydration for the gem. It is found in a host of crushed trachyte in between limonite and sandstone. Bulgarian turquoise hails from the Eastern Rhode Mountains and is unique in its existence in raw Spaheivo fields of lead (zinc ore).
Climate directly influences turquoise growth. If it is forming in a location with modified volcanic rock, it will fill in the cavities. In the southwestern U.S., it is commonly paired with copper sulfide deposits and wears down whatever is in the potassium-feldspar porphyritic.
Formations and Formulas
Simply put, turquoise is a hydrated copper and aluminum phosphate mineral. Its chemical formula is CuAl6(PO4)4(OH)8·4H2O. It is chemically classified as phosphate.
The mineral is created when acidic, copper-infused water encounters the weathering and oxidation of minerals that already existed (those with phosphorus and aluminum in them). It then goes through a sedimentary phase.
In a similar manner, copper can derive from copper sulfides like chalcopyrite, and aluminum can drive from feldspar. This mineralization process occurs in a shallow depth, around 66 feet on most occasions - this is due to a few outside factors, one being high water tables.
Crystals and Texture
This mineral is a combination of microcrystals. This should not be confused with a gem found in a fully-formed crystal. A finer texture comes when the crystals are tightly bound together, leaving less room for porous properties. When turquoise has a fine texture, it can produce a waxy luster when polished.
The opposite is true for findings that are surrounded by loose crystals - porousness creates a coarse texture that is dull rather than waxy. Coarse turquoise contributes to undesirable toughness. This is why pieces that are less porous and fine in texture are the most valuable and sought after. In fact, if you do come across a coarse stone, it has probably already been smoothed and shined with treatments to increase its aesthetic appeal.
The Power of Water
Water has a great impact on the creation of turquoise, its survival after formation, and whether or not it can be found.
In Egypt, mining turquoise occurs on a small scale because it exists in dangerous areas. These sandstone spaces are prone to flash flooding in the summer, which creates a safety hazard for workers as the walls are always threatening to cave in.
Fine turquoise is admired for its natural shades of sky blue, blue-green, green, and yellow-green. It is not uncommon to find a piece with bluish-white or greenish-white streaks.
Here are some other characteristics of the mineral:
- Luster: Waxy to sub-vitreous. It can appear dull when it has been worn down.
- Transparent to opaque.
- Cleavage: Not visually evident, but perfect.
- Specific Gravity: 2.5 to 2.9.
- Crystal System: Triclinic.
Creation of the Matrix
Since turquoise forms as deposits in limonite or sandstone that contains iron, different markings come out due to different interactions. Limonite is known to create bark marks in the stone, and sandstone adds tan marks. They showcase the remains of the host rock the turquoise once grew in.
These markings can look similar to veins and are called matrix; very thin versions are dubbed spiderwebs. More matrix in a piece of turquoise significantly lowers its value in terms of fine jewelry.
Typically, a jeweler would try to remove the matrix if the chunk of turquoise is in one place. When small composites throughout a host rock are separated, it can be difficult to have enough of the gem to not include the matrix.
Apart from turquoise that is clean, spiderweb matrix is the second-highest in value. Some enjoy it for its visual contrast as dark spots contrast from the brightness of the blue hues.
Turquoise falls somewhere between a five and a six on the Mohs scale for hardness, which is fairly low (it is only a little bit above glass). This means that the mineral is fairly fragile and has poor wearability without protection. However, in capable hands, turquoise can be formed into pieces that will last for years.
Ancient and traditional Indigenous cultures utilize the malleability of soft turquoise for carving, especially when it comes to talismans.
Sleeping Beauty Mine
Among the southwestern U.S. mines, two in Arizona are likely the most well-known. Kingsman Mine offers a bright blue turquoise that contains the black matrix in a spiderweb formation. The Sleeping Beauty Mine, which we partner with for all of our turquoise jewelry, has the highest-quality sky blue offerings with absolutely no matrix.
The Sleeping Beauty Mine stopped production in 2012 due to its overwhelming demand and separate future mining prospects. The remaining turquoise was purchased and dispersed, still circulating in jewelry and fine gem circles.
At Mark Henry Jewelry, we are thrilled to share our Sleeping Beauty Collection with pieces such as the Heart of Love necklaces featured in our Valentine’s Day Gift Guide. The impressive piece places a suspended turquoise in a heart-shaped setting, surrounded by diamonds on an 18k gold chain.
Types of Marketable Turquoise
Stabilized turquoise includes a polymer material meant to bind together its pores and create longer-lasting durability. It can be beneficial in creating jewelry pieces prone to an active lifestyle, like rings. It is the most commonly acquired version of turquoise, but the presence of the polymer should always be fully advertised to the consumer.
Composite or reconstituted turquoise brings together small pieces of the gem and polymer material to create blocks, which are then cut into cabochons, beads, and more. This is very far from fine jewelry and can even be labeled as “man-made.”
Similarly, some turquoise may be dyed to make colors more uniform if the piece has large pores or a polymer and matrix have discolored it. Synthetic and imitation turquoise was popularized by the Gilson Company in the 1980s and included ceramic, glass, and plastic. It can be weeded out quite quickly when compared with the true hardness, specific gravity, and refractive index of raw turquoise.
To Delight and Admire
With three decades of knowledge and expertise, we have been honored to not only share our fine jewelry findings but create a community of gem lovers who can identify and understand where their favorite pieces came from.
When in doubt, reach out to a gemologist or jeweler for advice on the origins of your turquoise. We have a contact form conveniently located on our website for all comments, concerns, and interests. After all, the full story is always more riveting.