Gem Profile- Serpentine

by Judy Ellis

As we've progressed through these profiles, you've probably noticed that the naming of stones can be pretty varied and interesting. Some are named after people; some have names derived from Greek or Latin words; and others are named simply for the appearance of the stone. Serpentine is one stone named for its appearance, using the Latin word serpentinus which means serpent-like.

Serpentine is translucent green, though is also found in yellow, white and gray, with a mottled appearance that looks like scales and is often described as having a "greasy" or silky feel and had a harness of 2.5-3.

Shawnea Hardesty created this Serpentine jewelry set - serpentine earrings and a serpentine pendant - for her mother.

The Serpentine Group

Serpentine is the "brand name" for a group of polymorphous rocks within the serpentine group, sometimes called serpentinite. Polymorphous means the rocks share the same chemical composition, but their molecules are arranged differently.

The hydrous magnesium iron phyllosilicate polymorphs of serpentine are classified as antigorite, chrysotile, and lizardite. They are chemically identical but have different bonding structures. In other words, the serpentine group includes serpentine, antigorite, lizardite, and chrysotile, all green stones with a scaly appearance and the same basic chemical structure.

The appearance of serpentine depends on the bond structure at the time of metamorphosis. Antigorite is named after the Antigoro Valley in Italy, where it is commonly quarried.

Antigorite is also found in Rhode Island, where it is compacted and called bowenite, the state mineral, as well as in Maryland and Pennsylvania. It forms in fine plate-like crystals bonded with mica and is used for carvings, beads, and jewelry.

It can even serve as a substitute for jade.

Kosadinka Dobreva created this serpentine pendant with a round cabochon and a Viking Weave Bezel

Lizardite, the most common type of serpentine used in home décor, is often called green marble. It is a fine-grained serpentine with perfect cleavage and can appear white, yellow, or green.

The type we have in our home is usually dark green with veins of calcite running through it. Lizardite takes a high polish and is harder than marble, though it doesn't weather well outdoors.

The most common form of serpentine is chrysotile, which forms in cylindrical crystals that double back on themselves, creating long threads of asbestos within the rock.

Chrysotile is valued for its asbestos fibers due to their fire resistance and flexibility. It is mined in New York, New Jersey, and other areas along the Appalachian Mountains, as well as in California, Arizona, and Quebec near the town named Asbestos.

Serpentine and Asbestos: You're Safe

We are all familiar with the health risks from asbestos so as a side-note here; asbestos confined within a stone is not dangerous, it becomes a health risk only when it is airborne. Asbestos workers are the most at-risk for health concerns from overexposure to asbestos and industry standards have been changed to protect them. This all sounds very scary; I mean who wants to put their health at risk over a rock?

Well, put the fear away and keep in mind that though asbestos may create health problems, it's really only been seen in people who work in industry where there is an overexposure to asbestos fibers and as long as asbestos is sealed, either within the stone or through other means, the health risk is minimal.

Finding Serpentine: California Road Trip!

Let's head to California, where serpentine is plentiful, beautiful, and the official state rock!

Serpentine forms from rock under high pressure and low heat, which is why it is often found in basalt along the sea floor. In California, tectonic movement and subduction have pushed serpentine to the surface, covering much of the state.

You can identify serpentine soil by its distinct look. It is not very hospitable to plants and contains a lot of clay, so the green stone often appears with very sparse vegetation.

Joan Madouse wrapped this serpentine stone in bronze wire.

Resources & Recommended Reading

Serpentine Group on Wikipedia
Bowenite on Wikipedia
Serpentine (Chrysotile): www.thoughtco.com
Mount Tamalpais State Park: www.parks.ca.gov

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