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Quartz thin section

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About Quartz
Apparently from the Saxon word querkluftertz, meaning cross-vein ore, which could easily have become condensed to querertz and then to quartz; the idea is supported by the old Cornish name for crystalline silica which means cross-course-spar; in any case the word is from German and of ancient derivation.
Quartz hand-specimen
Formula: SiO2
System: Trigonal
Color: Colorless, Purple, Rose, Red, Black, Yellow, Brown, Green, Blue, Orange, etc.
Lustre: Vitreous
Hardness: 7
Density: 2.65–2.66
XPL
XPL
XPL
PPL
PPL
Quartz #1 thin section (hFOV 2mm)
XPL
XPL
XPL
PPL
PPL
Quartz #2 thin section (hFOV 2mm)
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Quartz PPL properties
Relief: Low positive
Habit/Form: Typically anhedral granular to highly irregular in igneous and metamorphic rocks. Detrital grains are usually more or less equant.
Color: Colorless, clear (with no alterations); it often contain inclusions
Pleochroism:
Cleavage:
Quartz XPL properties
Isotropy/Anisotropy: Anisotropic
Interference color: Order I white; quartz is very useful in determining the thickness of any slide in which it occurs.
Extinction angle:
Twins: Absent
Uniaxial/Biaxial: Uniaxial (+)
Optic axial angle (2V):
Quartz 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