Home Silicates Phyllosilicates Serpentine thin section

Serpentine thin section

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About Serpentine
(Mineral group name), from Latin serpens (= snake), in allusion to the surface pattern of some serpentinite rocks, which resemble the skin of a serpent.
Serpentine hand-specimen
Formula: (Mg, Fe, Ni, Mn, Al, Zn)3Si2O5(OH)4
System: Monoclinic
Color: Green, green-blue, white, brown, black
Lustre: Vitreous
Hardness: 3–4
Density: 2.5–2.6
XPL
XPL
XPL
PPL
PPL
Serpentine #1 thin section (hFOV 2mm)
XPL
XPL
XPL
PPL
PPL
Serpentine #2 thin section (hFOV 2mm)
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Serpentine PPL properties
Relief: Low-Moderate positive
Habit/Form: Fibrous serpentine is typically chrysotile and it commonly forms veins with fibers across the width or matted masses. Lizardite is commonly very fine-grained and may form an irregular net-like pattern with uneven or undulatory extinction. Antigorite is often more or less micaceous and may form foliated or scaly masses. However, different varieties may be intergrown, and habit is not always a reliable guide to variety. Serpentine is typically produced as a consequence of alteration of minerals such as olivine and pyroxene, and remnants of those minerals are commonly found within masses of fine-grained serpentine. Greenalite, berthierine, and amesite typically form very fine-grained aggregates that are colorless to light green and are less common as folia resembling chlorite.
Color: Colorless to pale green
Pleochroism: Absent to weak
Cleavage: Perfect basal cleavage {001} is characteristic of all sheet silicates. Antigorite, commonly shows characteristic foliation.
Serpentine XPL properties
Isotropy/Anisotropy: Anisotropic
Interference color: Order I gray to pale yellow or pale olive
Extinction angle: Parallel / 0° / straight to the length of crystals/fibers
Twins: Absent
Uniaxial/Biaxial: Biaxial (-)
Optic axial angle (2V):
Serpentine distinguishing features under the microscope
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References
  • Deer, W. A., Howie, R. A., & Zussman, J. (2013). An introduction to the rock-forming minerals (pp. 498). Mineralogical Society of Great Britain and Ireland, London.
  • mindat.org – The Mineral Database