処理...

Staurolite Gemstone: Properties, Meanings, Value & More

スタウロライトの宝石：特性、意味、価値など

このテキストは機械翻訳されました。 オリジナルを表示しますか？

Staurolite (star-oh-light) is a brown mineral known for its distinctive cross-shaped crystal habit. Is staurolite a gemstone? Yep! These stones are also cut into gemstones, though collectors usually seek out well-formed staurolite cross crystals in their raw form. 

Is staurolite a rare mineral? No, the staurolite mineral is fairly common. However, transparent staurolite suited for faceted stones is scarce. Plus, staurolite’s capability for twinning at both 60° and 90° is a super rare quality among crystals. 

In the US state of Georgia, staurolite is the official state mineral. It was likely chosen because of the stone’s relative abundance in the area. Plus, some of the highest-quality staurolite specimens come from Fannin County.

Ready to learn more? Join us as we go over staurolite’s meaning (including why it’s called the fairy stone), properties, and process for attaining its unique cruciform look. 

About Staurolite Stone

Staurolite is a semi-precious gemstone naturally possessing a cross shape, similar to chiastolite (pictured below). While chiastolite’s cross is internal, resulting from inclusions, staurolite’s cross is a three-dimensional shape from its crystals intersecting. Still, both stones have nicknames with the word “fairy” in them.

Speaking of, some of staurolite’s nicknames include:

• Fairy Stone

• Fairy Cross / Fairy Cross Stone

• Fairy Tears

• Baseler Taufstein (German for “baptismal stone”)

There’s also a rock used in jewelry called “Canadian fairy stone” that’s a uniquely formed concretion usually found in gray tones. These are different from staurolite. 

Outside of gems, what is staurolite used for? The main industrial staurolite uses are similar to garnet, as both are used as abrasives. While searching for the stone, you may see “staurolite sand” come up. But what is staurolite sand?

Staurolite sand is a lighter-colored (often orange) abrasive material containing staurolite. Because the mineral is weathering-resistant and fairly durable, it’s used in sandblasting. 

Astrologically, these enchanting crystals are the perfect zodiac stone for Pisces, the more dreamy, spiritual sign of the zodiac. 

Pictured above: Chiastolite, another "cross stone" with an internal cross

Staurolite Specifications & Characteristics

Staurolite is an aluminum nesosilicate with a somewhat complicated formula. 

The staurolite formula may be written as (Fe,Mg,Zn)2Al9Si4O23(OH) or Fe2+2Al9Si4O23(OH) or even 4Al2O[SiO4].AlFe2+2O4. The composition can also be described as kyanite and oxide creating alternating layers. 

The mineral’s signature cruciform trait comes from a type of crystal growth called twinning. Twinning happens when two separate crystals of the same mineral are conjoined in some area(s). 

Staurolite twinning falls under the penetration subtype, where two rectangular crystals intersect each other during their growth, sharing a perpendicular centerpoint. This happens at either 60° or 90° to produce a cross-like shape composed of prismatic crystals. Outside of twinned crystals, staurolite can also form as a massive material. 

The remaining staurolite properties are listed below:

• Mohs hardness: 7-7.5

• Color: Shades of brown, reddish-brown, brownish-black, yellowish-brown

• Crystal structure: Monoclinic; Pseudo-orthorhombic

• Luster: Vitreous (glassy), subvitreous, or resinous

• Transparency: Translucent to opaque, rarely transparent

• Refractive index: 1.739-1.761; Zincian - 1.721-1.731

• Density: 3.65-3.83; Zincian - 3.79

• Cleavage: Distinct on [010]

• Fracture: Conchoidal

• Streak: Colorless/white or light gray

• Luminescence: None

• Pleochroism: Present and distinct in colorless and yellow or red and golden yellow; Zincian staurolite - green, red, and yellow

• Optical effects: Color-changing

• Birefringence: 0.011-0.015

• Dispersion: 0.023

What’s with the “zincian” listings above? Glad you asked!

Image credit: Carptrash at English Wikipedia | Creative Commons Attribution-Share Alike 3.0 Unported license

Types of Staurolite

Staurolite has two variants, meaning subtypes that are too similar to the original material to be considered varieties. These staurolite variants are zincian staurolite and lusakite.

Zincian staurolite contains zinc, which alters its mineral properties a bit (as you can see in the properties list above). These types of staurolite are quite rare, but their paler coloring makes them beautiful faceted gems.

Another unique and rare quality of zincian staurolite is its ability to change color. Zinc-bearing staurolites can be reddish-brown under incandescence, then yellow-green under sunlight. 

Lusakite is a staurolite variant containing cobalt, giving it a deep blue coloring. Its name comes from its main source: Lusaka, Zambia. 

Next, we’ll look at some of the folklore and history behind the “fairy cross stone.”

Staurolite Meaning & History

The name “staurolite” comes from the Greek word stauros meaning “cross,” for… pretty obvious reasons at this point. From a secular view, the staurolite crystal generally symbolizes healing from trauma, finding your strength, and connecting to your inner light. 

Staurolite’s spiritual meaning has been interpreted in various ways throughout history, with a couple of folktales tied to its origins. 

One rather melancholy Native American legend states that staurolite formed from the tears of Cherokee people traveling the Trail of Tears. The Trail of Tears was a period from 1837 to 1839 where roughly 60,000 Native Americans were forced to move via a deadly route toward western America.

But why is staurolite called “fairy stone?” Or “fairy tears?” 

Well, a similar Virginian folk tale claims staurolite formed centuries ago when fairies near a real-life staurolite deposit heard the news of Christ’s crucifixion. In their mourning, their tears fell and crystallized into staurolite.

Outside of fantasy creatures, the book that recalled this Virginian legend (George F. Kunz’s The Curious Lore of Precious Stones from 1913) also describes some of the history and other beliefs surrounding staurolite. 

History

Perhaps the most common interpretation of staurolite’s meaning over time is that it brings good luck. This doesn’t just apply to spiritual folks, either — politicians and inventors like Thomas Edison, Theodore Roosevelt, and Woodrow Wilson wore staurolite for good luck. 

According to Swedish mineralogist Axel Frederik Cronstedt’s 1758 treatise, staurolite was called Baseler Taufstein (for “baptismal stone”) in Basel, Switzerland. This name came from the practice of wearing staurolite amulets during baptisms.

Similarly in France, an old name for staurolite was “Cross of Brittany.” Legends in France claimed staurolites fell from heaven, and France had an abundance of staurolite deposits. Germans called it Taufstein, often decorating baptismal fonts (a large water basin used for baptisms) with the stone.

Perhaps unsurprisingly, Christians throughout time have considered staurolite a symbol of Christ, just like a typical cross necklace would be. Moreover, some Christians believe wearing staurolite jewelry encourages you to be more like Christ (i.e. faithful, empathetic, honest, etc.) and generously share your blessings.

Because of the high demand for these spiritual stones, imitations have been sold since the early 1900s.  

Speaking of their spiritual nature, let’s discuss staurolite’s healing properties.

Staurolite Healing Properties

Even outside of religious contexts, staurolite can be used as a healing stone. As a predominantly brown gemstone, staurolite inherently offers grounding and balancing benefits. 

But what about staurolite’s physical, emotional, and chakra healing benefits? 

Physical Healing

Physically, staurolite is used for:

• Lowering fevers

• Improving blood circulation

• Strengthening muscles

• Treating cellular disorders

• Helping the body absorb carbohydrates

Emotional Healing

In a time where an obsession with hyper-productivity and burnout are becoming public epidemics of their own, staurolite is a helpful tool. It’s believed to ease stress and encourage you to prioritize self-care to prevent burnout. 

Additionally, crystal healers recommend staurolite for helping treat depressive disorders, addiction, and alcoholism. The crystal is said to help you address repressed, negative emotions so you can properly heal and move forward with greater strength and acceptance.

Chakra Healing

Chakra healing involves balancing energy flow among the seven chakras (energy centers) along your body. Staurolite chakra stones align the root, heart, and third eye chakras. 

While the root chakra is about fundamental needs, the heart focuses on love and the third eye on spiritual intuition. When they’re aligned, you can stay grounded as you explore your highest spiritual self. 

Image credit: Eurico Zimbres | Creative Commons Attribution-Share Alike 3.0 Unported license

Staurolite Gemstone Properties

Staurolite’s value depends in part on how rare each specimen’s traits are. Experts determine the value in general based on color, cut, clarity, and carat weight, along with whether the stone is natural and has been treated or not. 

Color

Staurolite’s color always has brown, sometimes with undertones of red, yellow, or black. The brown coloring comes from the stone’s ferrous iron (Fe2+) content. 

Other colors come from various impurities, like the reddish-brown to yellow-green color changes in zinc-bearing specimens or the blue of cobalt-bearing lusakite. 

Other impurities include titanium, chromium, manganese, lithium, and water.

Cut

Transparent, facetable staurolite material is rare, making faceted staurolites the most valuable, especially if they’re color-changing. Unfortunately, faceted staurolites are often dark and small, making their colorful dispersion harder to see. 

More often, translucent to opaque specimens are cut into cabochons (without the typical smooth top) or cameos (carvings with a raised image). These are often used for religious jewelry or lucky amulets. 

Clarity

Since most staurolites are dark and opaque, clarity (the number of visible inclusions) doesn’t affect their appearance much. However, visible inclusions may affect the value of transparent staurolite gems.

Common inclusions in staurolite are quartz or garnet crystals. Specimens may also have surface cavities, which lowers their durability. 

Carat Weight

The largest known staurolite twinned crystal is only 9 cm (or 3.5 in). Faceted gems are always small, usually 2 carats or less. 

Treatments & Simulants

Twinned staurolites may be dyed, oiled, or filed. Filing is done to smooth surface cavities and make the cross terminations more defined. While dyeing is done for appearance, oiling may be done to increase stability. 

Staurolite’s religious and spiritual significance has also led to various imitation stones. Based on early-1900s analysis by American mineralogist Joseph K. Roberts, many imitations were composed of talc and oiled or dyed to be darker. Some simulants may even have artificially created pockmarks (crater-like depressions) to look more like real staurolite. 

But how does real staurolite form?  

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Staurolite Formation & Sources

Staurolite forms through regional metamorphism when heat and pressure transform the mineralogy of sedimentary shale rocks. 

You’ll find staurolite in metamorphic rocks like gneiss and schist, often beside similarly aluminum-rich silicates like garnet, kyanite, and cordierite. Because it’s resistant to weathering, you may also find loose staurolite in alluvial river deposits. 

Geographically, where is staurolite found?

Mining Locations

In terms of facetable staurolite crystals, these rarities typically come from Brazil, Sri Lanka, or Switzerland. The USA boasts an abundance of “fairy cross” staurolites, with staurolite rockhounding sites for tourists. These sites include Virginia’s Fairy Stone State Park and Blanchard Dam in Minnesota. 

Other significant American locales include Fannin County in Georgia and Hondo Canyon in New Mexico. 

Additional locales for staurolite (and its variants) include:

• Canada

• France

• Russia

• Scotland

• Spain

• USA (Connecticut, Maine, New Hampshire, North Carolina, Tennessee, Vermont)

• Zambia — Lusakite

Now, let’s talk about cost.

Image credit: MarchHare1977 at Russian Wikipedia | Creative Commons CC0 1.0 Universal Public Domain Dedication

Staurolite Price & Value

Staurolite prices depend on the cut — faceted pieces are the most expensive, while other cuts are pretty affordable. 

Faceted staurolites are about $250 per carat. Staurolite cabochons range from around $10 to $60. Rough specimens go for $25 to $120, though huge ones can be above $400. 

The average staurolite jewelry prices are:

• Rings: $25 to $100

• Earrings: Around $45

• Pendants: $20 to $180

Lastly, we’ll cover gemstone care. 

Staurolite Care and Maintenance

Though most staurolites are hard and durable enough for everyday wear, staurolites with surface cavities from fractures that reach the stone’s surface are more fragile. These specimens are also more prone to becoming dirty, as debris can easily get trapped in the cavities. 

To safely clean staurolite, use the standard method of lukewarm water, mild soap, and a soft toothbrush. Avoid cleaning the gem with ultrasonic devices, steam cleaners, or harsh chemicals. 

Reach for the Stars with Staurolite!

You don’t have to be religious to reap the benefits of the “fairy cross stone” staurolite — anyone can enjoy this crystal’s grounding and strengthening properties. During hard times, staurolite serves as a reminder that without the dark, we’d never see the stars.  

Buy staurolite gemstones today!