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Palygorskite: Properties, Meanings, Value & More

坡缕石：属性、含义、价值等

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Palygorskite (pronounced PAL-ee-GORS-kyte) is a fibrous clay mineral with a variety of commercial uses. It’s rarely seen as a jewelry gemstone, but it has value as a unique collector’s stone and industrial material.

The mineral is also called attapulgite (among other names), but what is the difference between attapulgite and palygorskite? It depends on who you ask and when.

In the past, palygorskite and attapulgite were considered quite similar but with different formation methods, crystallinities, and fiber lengths.

Some still follow these definitions and even consider attapulgite a subspecies of palygorskite. However, most scientists consider them synonyms, prioritizing “palygorskite” as the correct mineralogical name.

We have plenty more monikers to cover, along with palygorskite uses, history, prices, and properties!

Pictured above: Large sheet of papery palygorskite from Washington, USA | Image credit: John Krygier, Public Domain

About Palygorskite Stone

Palygorskite (or polygorskite) is sometimes used as a semi-precious gemstone. Though once considered a rare mineral, palygorskite is quite common.

Besides attapulgite, palygorskite’s other nicknames include:

• Rock Wood

• Mountain Leather (for fibrous, tangled mats)

• Angel Skin Opal

These are technically misnomers, but the first two reflect the common appearances of fibrous palygorskite aggregates resembling wet newspaper. The last one refers to “angel stone,” covered more later.

Industrially, what are the uses of palygorskite?

Palygorskite Uses

Palygorskite has a wide range of industrial uses. Its absorbency, along with other benefits like durability, particle size, and more, have been utilized in:

• Drilling fluid

• Catalysts

• Mortar & cement filler

• Medicines (mostly anti-diarrheal and potentially topical painkillers)

Note: Medicines often use the term “attapulgite” instead.

One specific palygorskite clay use is in “fuller’s earth.” We’ll get into the history of it later, but today, fuller’s earth containing palygorskite is used in:

• Woolen cloth (absorbing oils & grease and whitening)

• Pet litter

• Fertilizer & pesticide (carrier)

• Paint, adhesive, and plaster (filler)

• Cosmetics (treating facial pigmentation and cleansing hair or skin)

• Clothing & equipment decontaminant for military and emergency services personnel

• Marble cleaner

• Film & television makeup, wardrobe, or set (to look “dirty”) and special effects (like dust in tornados and explosions)

With all that value, what is palygorskite made of?

Pictured above: Silky white palygorskite on calcareous dolostone from Virginia, USA | Image credit: John Krygier, Public domain

Palygorskite Specifications & Characteristics

As a hydrous magnesium aluminum phyllosilicate (clay) mineral, palygorskite’s chemical formula is (Mg,Al)2Si4O10(OH)·4H2O. Common impurities are iron and potassium.

Sepiolite is closely related, forming a series with palygorskite. Some mineralogists classify palygorskite in the sepiolite mineral group, but palygorskite has its own group. Other members in the palygorskite mineral group include:

• Tuperssuatsiaite

• Windhoekite

• Windmountainite

• Yofortierite

Ribbon-chains of amphibole-like silicates make up palygorskite’s structure.

Externally, palygorskite can occur as bundles of elongated crystals, intergrown fibers in thin sheets, tangled fibrous mats, compact masses, or lath-shaped crystals.

Palygorskite properties listed:

• Mohs hardness: 2-2.5 (pure); 4.5 (angel stone)

• Color: White, gray, light pink, yellow, grayish-green

• Crystal structure: Monoclinic

• Luster: Dull, waxy, or earthy

• Transparency: Translucent

• Refractive index: 1.522-1.548 (pure); Around 1.55 (angel stone)

• Density: 2.21-2.60 (pure); 2.10-2.60 (angel stone)

• Cleavage: Distinct/good on {110} (pure); None (angel stone)

• Fracture: Uneven/irregular

• Streak: White

• Luminescence: None

• Pleochroism: Present in colored specimens - pale yellow to pale yellow-green

• Birefringence: 0.011-0.020

• Dispersion: Unknown

What’s “angel stone” in the list? One of palygorskite’s varieties!

Pictured above: Pre-1850 “pilolite” variety of palygorskite, also called “mountain leather” | Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Types of Palygorskite

Palygorskite has some varieties based on impurities or dominant elements:

• Mg Palygorskite: Magnesium-bearing; Most common

• Mn Palygorskite: Manganese-bearing

• Mn Ferro-palygorskite: Manganese and ferrous iron-bearing

• Pilolite: Historical term for (mostly) iron-bearing palygorskite, formerly called “vegetable asbestos”

There are also trade names for palygorskite mixed with other minerals, notably “angel stone.”

Angel Stone & Pink Opal

“Angel stone” refers to an opaque, microcrystalline palygorskite impregnated with amorphous (non-crystalline) silica. It’s often pale pink but can be gray or yellow.

The silica makes palygorskite more suitable for gemstone use. Another moniker is “angel skin opal,” but this is a misnomer.

However, palygorskite is found in many pink common opals as an inclusion that gives them their pink coloring.

Pictured above: Pink opal colored by palygorskite

Palygorskite History

The first official discovery of palygorskite occurred in the Second Mine, located in the Palygorsk Range of Russia. Russian scholar T. von Ssaftschenkow (or Savchenkov, translations differ) published his discovery in 1862.

In 1913, Soviet-Russian geochemist and mineralogist Alexander Evgenyevich Fersman named the mineral after the Russian location.

In 1935, French lithologist Jacques de Lapparent also found palygorskite in Mormoiron, France, and the Attapulgus area of Georgia, USA. He named it “attapulgite” after the latter location.

However, palygorskite uses go centuries back.

Pictured above: 7th to 8th century Mayan costumed figure with Maya blue pigment | Image credit: Metropolitan Museum of Art, Public Domain

Ancient Maya Blue

Ancient Mayans and Aztecs used palygorskite most prominently to make “Maya blue” pigment. The pigment is incredibly durable, withstanding weathering and chemical agents for thousands of years.

This vibrant azure blue pigment, first known around 500-800 AD, was mostly a combination of palygorskite and indigo from añil leaves.

Pre-Columbian maya blue uses include:

• Artwork (paintings, sculptures, murals)

• Textiles

• Codices

• Painting bodies & sites of human sacrifices

In the 1500s, colonial churches and convents used maya blue in their frescos, often in Arte Indocristiano (“Indochristian art”) style pieces. Cuban Maya blue uses continued until the 1830s.

Scientists rediscovered the pigment in 1931. They determined the composition in the 1950s. In 1993, Mexican historian and chemist Constantino Reyes-Valerio published a recipe to reproduce it, leading to his collaboration with European scientists to create similar pigments like “Maya Violet.”

Pictured above: 18th century engraving of Scotswomen fulling cloth and singing | Image credit: www.marariley.net/celtic/scotland.htm, Public domain

Fuller’s Earth

“Fulling” is a wool preparation step involving cleansing and shrinking woolen cloth so it’s smooth, finished, and water-repellent. This practice dates back to ancient times and still exists today.

Historically, fullers used water and types of clays called “fuller’s earth” to absorb lanolin (wax), grease, and oils in the cloth. These clays were usually made of bentonite or palygorskite. They also functioned as whitening and filtering agents.

Since then, fuller’s earth uses expanded, highlighted in the Palygorskite Uses section earlier.

Palygorskite Healing Properties

As a popularly pink healing stone, palygorskite shares the properties of with other pink gemstones like boosting self-love and acceptance.

Physical Healing

Unlike the spiritual healing properties of many stones, palygorskite has many scientifically backed studies to back its healing properties like:

• Antibacterial agent

• Adsorbent of toxins, viruses, and bacteria in the intestine

• Poison treatment

• Anti-diarrheal

• Skin wound healing

Emotional Healing

Emotionally, palygorskite is said to have soothing, calming, and nurturing properties. The crystal may help you accept yourself and others, facilitating all forms of love and compassion.

Chakra Healing

Chakra healing involves opening an energy center (chakra) that’s blocked. Palygorskite is a heart chakra stone.

The heart chakra is located at the heart (shocker, right?). It governs matters of love, spirituality, and acceptance. When it’s blocked, feelings of apathy, low self-worth, and isolation arise.

Using palygorskite, you can open your heart chakra, which harmonizes the spirit, body, and mind while helping you open your heart to love, treating others compassionately, and accepting the ups and downs of life.

Pictured above: Fibrous white palygorskite and pale yellow calcite crystals on a dark matrix | Image credit: John Krygier, Public domain

Palygorskite Gemstone Properties

Most palygorskite gemstones are “angel stone” varieties and lack standard grading. We’ll still cover how the standard value factors apply to palygorskite:

• Color: Colored palygorskites (pink, yellow, green) may carry higher value than non-pleochroic, less desirable white types.

• Cut: Palygorskite and “angel stone” can be cut into carvings, beads, or cabochons.

• Size: Larger sized gemstones and intact specimens can be more valuable.

Now, how is palygorskite formed?

Palygorskite Formation & Sources

Palygorskite primarily forms when magnesium silicate or aluminosilicate minerals undergo alteration. It forms in clay soils, hydrothermal veins, granites, carbonate rocks, and serpentines. Rarely, it’s found in marine sediments.

Common associated minerals are:

• Calcite

• Dolomite

• Axinite-(Fe)

• Mimetite

• Talc

• Chlorite

• Quartz

• Chalcedony

• Opal

• Montmorillonite

• Chalcophanite

• Epidote

• Orthoclase

Now, geographically, where can I find palygorskite?

Mining Locations

The mineral is spread out worldwide, but “angel stone” is primarily from Mexico and Peru.

Other notable sources of palygorskite are:

• USA (Florida, Georgia, Virginia, Washington)

• England

• France

• Morocco

• Russia

• Scotland

Industrially useful deposits are mostly in:

• Brazil

• China

• India

• Russia

• Senegal

• Spain

• USA

Pictured above: Rows of colorless calcite crystals held together by layers of papery palygorskite | Image credit: John Krygier, Public domain

Palygorskite Price & Value

Palygorskite clay for sale is pretty cheap, at around $12 to $50 per pound.

Most palygorskite gemstones are angel stones or pink opals. Pink angel stone rough specimens range from around $40 to $900, most falling under $100.

Palygorskite rough ranges from $15 to $45 or $100 to $630 or higher if it’s attached to calcite.

At our Opal Auctions site, pink opal prices are around:

• Faceted: $60 to $100 per carat

• Cabochons: $1 per carat

• Rough: $0.10 to $0.20 per carat

You can also find pink opal palygorskite beads for around under $1 per carat.

Palygorskite Care and Maintenance

Lastly is gemstone care. Palygorskite is quite soft, so be cautious to avoid scratches and use protective settings on jewelry.

You can clean it with a soft microfiber cloth.

Store it separately from other gems away from any moisture.

Want A Palygorskite Pal?

It has a funky name, but this gem is useful in so many ways, including beautiful pink opals and “angel stones” as a bright companion!

Buy palygorskite and more gemstones today!