Lizardite

Chemical formula: Mg<sub>3</sub>Si<sub>2</sub>O<sub>5</sub>(OH)<sub>4</sub>

Lizardite is a common mineral of the serpentine group, forming fine-grained, massive aggregates with a characteristic greasy or waxy luster.

## Characteristics Lizardite is a mineral from the serpentine group, being one of the three main polymorphs alongside antigorite and chrysotile. It most often occurs as compact, fine-grained, or cryptocrystalline masses. It rarely forms well-developed crystals, which are in the form of small, hexagonal plates. Typical specimens range in color from green, through yellowish-green, to whitish or gray. Its luster is characteristic, described as waxy, greasy, or silky. ## Physical Properties It is a very soft mineral, with a hardness of 2.5 on the Mohs scale, meaning it can be scratched with a fingernail. It has perfect cleavage in one direction, which manifests as a tendency to separate into thin plates or flakes. Its density is relatively low, approximately 2.55-2.64 g/cm³. To the touch, it feels smooth, sometimes slightly greasy. ## Colors and Varieties Lizardite takes on various shades of green, from light green to dark green, as well as yellowish, white, and gray colors. It often contains inclusions of other minerals, especially black magnetite, forming characteristic veins or spots. Rocks composed mainly of lizardite and other serpentine minerals are known by the commercial and petrographic name serpentinites and are a valued ornamental material. ## History and Name The mineral was formally described and named in 1955 by E. J. W. Whittaker and Jack Zussman. Its name comes from the place of discovery and first detailed study – the Lizard Peninsula in Cornwall (United Kingdom). ## Uses As a main component of serpentinite rocks, lizardite is mined along with them and used as a decorative and cladding stone. Due to their softness, serpentinites are easy to process and polish. Pure lizardite is mainly of scientific and collectible importance.

Properties

Mohs hardness
2.5
Luster
Waxy, Greasy, Silky
Streak
White
Density
2.55-2.64
Cleavage
Perfect on {001}
Fracture
Uneven
Transparency
Translucent to Opaque
Crystal system
Trigonal

Diagnostic features

## Identification Key diagnostic features of lizardite are its low hardness (2.5 on the Mohs scale), greasy or waxy luster, and perfect cleavage in one direction. It occurs as compact, fine-grained masses, often with a greenish color. Its occurrence in ultramafic rocks (serpentinites) is also characteristic. ## Distinguishing from Similar Minerals Distinguishing lizardite from other minerals of the serpentine group (antigorite, chrysotile) is very difficult without advanced studies (e.g., X-ray diffraction). Antigorite is usually slightly harder and has a more platy structure. Chrysotile forms distinct, separating fibers (asbestos). Talc is even softer (hardness 1) and feels soapy to the touch. ## Crystal Forms Lizardite almost always forms cryptocrystalline and massive aggregates. Single, well-developed crystals are very rarely observed, appearing as microscopic, flat, hexagonal plates.

Geological environment

## Genesis Lizardite is a typical low-temperature hydrothermal mineral. It forms as a result of serpentinization, which is the alteration of ultramafic rocks, such as peridotites and dunites. Water reacts with magnesium- and iron-rich minerals, mainly olivine and pyroxenes, transforming them into minerals of the serpentine group. ## Mineral Associations It most often co-occurs with other serpentine minerals (antigorite, chrysotile), as well as with magnetite, chromite, brucite, talc, magnesite, dolomite, and calcite. ## Localities As a rock-forming mineral, it is widely distributed worldwide. Classic and important localities include the Lizard Peninsula in Cornwall (United Kingdom), Val Malenco (Italy), Zermatt (Switzerland), the Ural region (Russia), as well as numerous sites in Canada (Quebec) and the USA (California, Pennsylvania, Maryland).

Rarity

Common

For collectors

## Quality Criteria For collectors, specimens from rare localities or those exhibiting unusual features, such as exceptionally intense color or distinct texture, are of greatest value. Since well-developed crystals are extremely rare, even microscopic plates in rock cavities are sought after by specialists. For massive specimens, aesthetics, color, and luster are important. Association with other, rarer minerals also adds value. ## Popular Localities Specimens from classic localities, such as Val Malenco in Italy or the Lizard Peninsula in the United Kingdom, are valued for their historical and scientific significance. Serpentinites from Quebec, Canada, also provide good quality material.

Care and storage

## Cleaning Lizardite specimens should be cleaned very carefully. It is best to use a soft brush to remove dust. If necessary, the specimen can be rinsed in distilled water, then thoroughly dried with a soft cloth. Ultrasonic or steam cleaners should not be used. ## What to Avoid Lizardite is very soft and prone to scratching. Avoid contact with harder minerals. It is also sensitive to acids, which can damage it. It should be protected from high temperatures and sudden changes in temperature. ## Storage Specimens should be stored separately, in padded boxes or wrapped in soft material, to avoid scratches and mechanical damage. It should not be exposed to prolonged direct sunlight.

External references

Sources

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