Photo of Serpentine in Processed & Rough Form
Serpentine is a mineral with a hardness of 5 out of 10 on the Mohs scale of mineral hardness [?]. These Monoclinicly structured gems are made of magnesium hydroxy silicate, their full chemical compound being Mg6(OH)8Si4O10.
Serpentine may refer to a single mineral but more often to a group of minerals including antigorite, chrysotile, clinochrysotile, and lizardite, which are altered products of basic and ultra-basic rocks. Rock composed of these minerals is called serpentinite. It comes in all the hues of green.
In mineralogy, serpentine is divided into three polymorphs, crystals with the same chemical substances but crystalling in different forms: chrysotile (or asbestos, fibrous serpentine), lizardite, or antigorite (leafy serpentine). Other mineralogists divide it only into serpentine and antigorite.
In gemology, serpentine is divided into common serpentine and noble serpentine or precious serpentine, which is translucent and oily-green. When it is waxy yellow to yellow green, it is known as retinalite.
Most serpentine is translucent, waxy, usually greenish white to soft, pale green. Sometimes, groups or rows of small, striking, whitish cloud shapes are visible on the inside. The yellow-green to definite green varieties are less common. Multicolored pieces are also found, with light green to green, yellow-green, or brown patches.
Serpentine is often confused with jade, but it differs from jadeite jade in having lower density and hardness. It is also distinguished from nephrite jade, which is normally a bit less translucent and less waxy. Despite the difference, serpentine is still being dyed to imitate jade and sold under the misleading name of "serpentine jade."
It is a common mineral, and occurs in the USA in numerous deposits and in Canada, and in the mountain belts of Italy, Greece, Afghanistan, the United Kingdom, Austria, France, Korea, China, India, and Myanmar.
Kaolinite-serpentine group minerals occur from the alteration of ultramafic rocks, igneous masses with a high content of magnesium-iron minerals. Bowenite in translucent green colours is found in New Zealand; attractive green williamsite is found at Rock Springs, Maryland, USA. Banded material is found in many places.
Ornamental serpentine is classified into two varieties; (a) the massive crystalline variety known as bowenite (known in Persian Farsi as sangi-yashm or in Chinese as Soochow jade and bastite) and (b) serpentine marble. Other varieties are massive, such as retinalite and ophiolite.
Bowenite is a hard variety of serpentine. A light green variety of bowenite, with the misleading name new jade, resembles nephrite, a variety of jade. Korean jade is a bowenite serpentine.
Most serpentine used for ornamental purposes comes from England, New Zealand, Korea, China, Italy, and the USA.
Other varieties in the serpentine group are:
Williamsite - Lamellar forms of serpentine that look like crystallized pages of a book, and is oil-green, translucent with white veins;
Satelite - a gray-blue, greenish variety which looks fibrous with inclusions, and has a cat-s-eye effect when polished;
Ricolite - a fine-grained serpentine with banded patterns in light green;
Pseudophite - a comparatively soft massive variety in a jade green color, incorrectly known as so-called Styrian jade;
Gymnite - a structureless mass form of antigorite serpentine, also known as dewelite.
Another source of serpentine is in Styrian, Austria, which is ornamental material sold under the name miskeyite.
Aside from jade, serpentine is also confused with onyx marble and turquoise.
The specific gravity [?] for Serpentine is 2.6, its refractive index [?] is 1.55-1.56, and its double refraction [?] is 0.001.
History
In New Zealand local serpentine was once carved into beautiful objects they called tangiwai, meaning "tears".
The lapis atracius of the Romans, now known as verde antique, or verde antico, is a serpentinite breccia popular as a decorative facing stone. In classical times it was mined at Casambala, Thessaly, Greece.
Antigorite is named from the Greek, "gymnos" meaning bare or naked.
Lizardite is named after its locality on the Lizard Peninsula in the United Kingdom.
Industrial Usages
Serpentine is mainly used for the carved figurines or decorated vases typical of Chinese art, most of them about 12 inches high. It is less tenacious than jade, but durable enough to be suitable material for the sculpting of classic vases with distinctive hanging chains carved from a single piece of stone.
Very elaborate compositions are often found, such as leafy branches, groups of birds, and flowering shrubs. Skillful use of different patches of color increases the value of such pieces.
But serpentine is used still more often for the large-scale production of low quality items, because it is less costly than true jade and easier to work, being less hard.
It is cut and polished as gemstones and cabochon, carved as cameos, intaglios, and ornaments. It is prized by collectors.
Its value is slightly lower than that of nephrite jade. It is therefore quite high for finely crafted-objects, but distinctly low for mass-produced items.
Only the green variety such as bowenite, ricolite, and the rarer, transparent/translucent apple-green williamsite (with black inclusions) are used for cutting and polishing into gemstone or cabochons.
Dyed serpentine is a variety of bowenite serpentine that has been stained with aniline to produce an imperial jade color to imitate jade, sold as serpentine jade.
Today, Oriental-style figurines have been produced from a light-green, translucent, waxy-looking plastic. These are highly deceptive at first sight, looking very much like serpentine. Their density is much lower, but it is not always easy to detect without proper measurement of its properties.
Serpentine has not been produced synthetically.
Serpentine-bearing rocks are used in building and as ballast material for railways. The fibrous variety, "chrysotile asbestos," is used for soundproofing and thermal insulation, but the use of this material has been much less in recent years, as it was discovered to be toxic, and studies into the death of railway workers proved that chrysotile asbestos fiber exposure brings about several severe health disorders such as mesothelioma and lung cancer.
In contrast, the gem-quality bowenite does not possess this toxicity, but instead is said to have healing properties for head discomforts and pains.
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