The word serpentine has been derived from ”Serpent”, which means greenish. Serpentines are so called because of their green colors. Serpentine occurs in two distinct forms: (i) ”Antigorite”; a platy variety, and (ii) ”Chrysolite; a fibrous variety.
Minerals species of Serpentine Group:
- Amesite: Chemical composition of Amesite is Mg2Al2SiO5(OH)4., however if an Amesite has Ni instead of Mg, it will be included in the Ni-Serpentine subgroup.
- Antigorite: Antigorite is a platy variety of serpentine minerals.
- Cronstedtite: It is a complex iron silicate mineral belonging to the serpentine group of minerals. Its chemical formula is Fe 2+ 2Fe 3+ (Si,Fe 3+. O 5)(OH) 4.
- Chrysotile: The fibrous form of serpentine group, which is used as a source of asbestos. Asbestos are used as fire-proofing and insulatory material in the buildings.
- Guidottiite: it is black in colour. Its is enriched with Manganese instead of Magnesium. Its chemical formula is Mn2Fe3+(SiFe3+)O5(OH)4. It is the first mineral of serpentine group discovered manganese constituent.
- Lizardite: It belongs to Jade Serpentine Group, which is used in carving.
Varieties of Serpentine Subgroup:
|Bastite||Name for pseudomorphs of serpentine-group minerals after enstatite.|
|Marmolite||Light green pearly serpentine, which may show a somewhat laminated fracture pattern.|
|Metaxite (of de Fourestier)||Variously described as a variety of antigorite or chrysotile.|
|Ni-Serpentine||A name for artificial serpentine-group minerals with Ni replacing Mg.
Essentially Ni-rich antigorite or amesite.
|Nickeliferous Serpentine||A nickel-bearing variety of serpentine.|
|Picrolite||Columnar or coarsely fibrous (non-asbestiform) variety of serpentine, commonly referred to as a variety of antigorite but may be other species.|
|Radiotine||A name for serpentine occurring in spherical aggregates of radiating fibers.|
|Retinalite||Honey-yellow to light green, massive, sometimes gem-quality, serpentine.|
|Ricolite||A variety of serpentine interbanded with talc.|
|Serpentinasbest||Asbestiform varieties of “serpentine”, i.e., members of the serpentine group (usually chrysotile).|
|Serpentine Jade||A dense cryptocristalline mixture of serpentine group minerals, mainly antigorite, chrysotile and lizardite, which is used for carving. It also contains a variety of minor impurities such as chlorite, ilmenite, magnetite and talc. Technically, this materi…|
Antigorite and Chrysotile: (Mg,Fe2+)3Si2O5(OH)4
- Crystal System: Minerals of the Serpentine group have a monoclinic crystal system.
- Cleavage: Though they are found in platy and fibrous form, therefore the platy variety has a good basal cleavage, while the fibrous variety has not cleavage.
- Hardness: Mineral of the serpentine group have a variable hardness between 4-4 as per Moh’s scale.
- Sp.Gr: The minerals have low specific gravity i.e. 2.5-2.6.
- Lustre: The fibrous variety of serpentine has silky lustre, while the massive/platy forms have greasy lustre.
- Colours: The minerals of Serpentine have green and brown colours with various shades.
- Habit: Lamellar, platy/massive, and fibrous habits. Chrysotile variety has a fibrous habit.
Occurrence of Serpentine Minerals:
Serpentine is usually formed by the alteration of magnesium silicates such as olivine, pyroxene, and amphibole. It is found associated with magnesite, chromite, and magnetite. Serpentine is a rock, which is made up mostly of the variety antigorite. It is formed by the alteration of olivine-bearing rocks.
Uses of Serpentine:
- The chrysotile variety of serpentine is the chief source of asbestos. Asbestos products are used for fire-proofing and as an insulation material against heat and electricity.
- Serpentines are used as a major source of magnesium.
- Serpentines are also used as decorative stones in the building.
- Guidottiite is a member of the Serpentine group, which is used in cosmetics to add “shimmer” or “frost.”
- Ricolite is used as an architectural material and ornamental stone and for decorative purposes.
- Minerals of Chlorite Group
- Minerals of Garnet Group
- Minerals of Olivine Group
- Minerals of Mica Group