Chrysotile

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What is Chrysotile Asbestos?

Chrysotile asbestos, commonly referred to as white asbestos, is one of the three primary types of asbestos, alongside actinolite and tremolite. Despite being incorrectly called Swiss opal, zebra jasper, lizard skin jasper, dragon scale stone, or green rose opal, chrysotile remains the most frequently encountered form of asbestos, accounting for approximately 95% of the world’s asbestos usage.

Chrysotile is a soft, fibrous silicate mineral belonging to the serpentine subgroup of phyllosilicates. This makes it distinct from other types of asbestos found in the amphibole mineral group. Its idealized chemical formula is Mg3(Si2O5)(OH)4, which reflects its structure as a hydrated magnesium silicate.

Why is Chrysotile Often Misnamed?

The stone has often been mislabeled as opal or jasper, primarily because many gem traders are not trained gemologists and thus rely on superficial visual similarities when naming stones. The majority of opaque stones are generally called jasper, while the name “opal” is sometimes applied due to the stone’s low density, which is somewhat comparable to that of opal.

One way to reliably identify chrysotile is by performing a simple test with water. When placed in water for about a minute, chrysotile’s fibrous, porous structure allows it to absorb the liquid, making the stone noticeably heavier afterward. Neither opal nor jasper will demonstrate this property, making this test an easy way to differentiate chrysotile from these other minerals.

Physical Properties of Chrysotile

Chrysotile asbestos has a hardness comparable to that of a human fingernail, making it relatively soft and easy to crumble into fibrous strands. These strands are composed of smaller bundles of fibrils that can vary in length from several millimeters to over ten centimeters, although chrysotile that has undergone industrial processing tends to have shorter fibers.

The fiber bundles typically measure between 0.1 to 1 µm in diameter, while the individual fibrils within these bundles are even finer, measuring between 0.02 to 0.03 µm. Each fiber bundle may contain dozens or even hundreds of these individual fibrils.

Despite their fine appearance, chrysotile fibers possess impressive tensile strength and can be spun into thread and woven into fabric. In addition to this, chrysotile fibers are also highly resistant to heat, making them excellent thermal, electrical, and acoustic insulators. This unique combination of properties led to the widespread use of chrysotile in a variety of industries during the 20th century.

Different Forms (Polytypes) of Chrysotile

There are three recognized polytypes of chrysotile, which are very challenging to distinguish by hand specimens alone. Typically, polarized light microscopy is required for proper identification. Some older literature refers to chrysotile as a group of minerals, listing three main polytypes: clinochrysotile, orthochrysotile, and parachrysotile, as well as pecoraite on occasion. However, according to the 2006 recommendations of the International Mineralogical Association, chrysotile is now treated as a single mineral with a degree of natural variation.

Clinochrysotile is the most common of these forms, with notable deposits in Asbestos, Quebec, Canada. Its two measurable refractive indices are generally lower than those of the other two forms. The orthorhombic polytypes, orthochrysotile and parachrysotile, can be distinguished based on their optical properties. For orthochrysotile, the higher of the two observable refractive indices is parallel to the long axis of the fibers (similar to clinochrysotile), whereas, for parachrysotile, the higher refractive index is perpendicular to the long axis of the fibers.

Microscopic Properties

Under a microscope, chrysotile can be identified by its fibrous nature and complex crystal structure. The fibers appear as fine strands that can intertwine, giving chrysotile its distinctive appearance. These fibers, though seemingly delicate, can be quite dangerous if inhaled due to their tendency to embed in lung tissue.

Health and Safety Considerations

While chrysotile is often associated with asbestos-related health hazards, there is no danger in handling polished gemstones that contain chrysotile, such as pietersite, serpentine, or nephrite, which are commonly used in jewelry. The real danger arises from inhaling powdered asbestos, which can lead to severe respiratory issues, including lung cancer and mesothelioma.

Most lapidary work involving chrysotile is done using water to minimize dust, and it is essential to ensure that these minerals are never worked dry to prevent inhalation of the fibers. If you are selling chrysotile or other asbestos-containing minerals, consider including a warning to inform customers not to grind or inhale the powdered mineral.

Chrysotile FAQs

What is chrysotile made of?

Chrysotile is the only known type of asbestos that belongs to the serpentine mineral family. It consists of curly fibers and has a layered structure, which distinguishes it from other types of asbestos, such as amosite or crocidolite.

How does chrysotile form?

Chrysotile forms through the process of serpentinization, in which ultramafic rocks or silicified dolomitic limestones are altered. The composition of the parent rock influences the trace metal content and the nature of associated minerals, such as fibrous brucite (nemalite) and tremolite.

Is chrysotile hazardous to health?

Chrysotile asbestos, like other asbestos types, can cause severe health problems when inhaled over extended periods. Studies have found cases of malignant mesothelioma in workers exposed to high levels of chrysotile, even when the presence of amphibole asbestos was negligible. However, when chrysotile is encapsulated in other materials, such as in polished gemstones, the risks are minimal.

How long does chrysotile remain in the lungs?

Research suggests that serpentine fibers, such as those of chrysotile, are broken down and removed by lung tissue macrophages within 3 to 6 months. This contrasts with amphibole fibers, which may remain in lung tissue for over 50 years, posing a more persistent health risk.

Where is chrysotile mined?

Major producers of chrysotile asbestos include Russia, Canada, China, Brazil, Kazakhstan, and Zimbabwe. In the year 2000, active mining operations for amosite asbestos fibers were found in 21 different countries.

Is chrysotile considered a mineral?

Yes, chrysotile is a mineral and is commonly referred to as white asbestos. It is the most exploited asbestos mineral and the only regulated serpentine variety. Other serpentine minerals, such as lizardite and antigorite, can also occur in fibrous forms, but they are less commonly used.

Natural Chrysotile for Sale

We offer custom-made chrysotile jewelry, including engagement rings, necklaces, stud earrings, bracelets, and pendants. Please contact us for a quote on a unique chrysotile piece tailored to your preferences.