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Lazurite thin section

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About Lazurite
Lazurite/Lazulite – from Persian lazhward (= blue). Lapis lazuli – from Latin for stone and Persian lazhward, meaning blue color.
Lazurite hand-specimen
Formula: Na6Ca2(Al6Si6O24)(SO4,S,S2,S3,Cl,OH)2
System: Cubic (Isometric)
Color: Ultramarine, midnight blue
Lustre: Resinous
Hardness: 5–5½
Density: 2.38–2.45
XPL
XPL
XPL
PPL
PPL
Lazurite #1 thin section (hFOV 2mm)
Lazurite PPL properties
Relief: Low negative
Habit/Form: Crystals are dodecahedra, which in thin section show six-sided cross section. Sodalite is often anhedral in plutonic rocks. Symmetrically or zonally arranged inclusions are common in nosean and hauynite. Phenocrysts may be partially resorbed and have embayed edges.
Color: Blue
Pleochroism:
Cleavage:
Lazurite XPL properties
Isotropy/Anisotropy: Isotropic; sometime anomalously anisotropic
Interference color: Isotropic (black)
Extinction angle:
Twins: Absent
Uniaxial/Biaxial: Isotropic (anomalous Biaxial)
Optic axial angle (2V):
Lazurite 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