Raman Spectra of a Granite section

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The Raman microscope can easily determine the mineralogy of a granite polished slab as shown below. All images are reflected light images  with oblique illumination.
Granite spot A: Quartz
Optically, it was not easy to see if spot A was Quartz or Feldspar.
 
The Raman spectrum shows that the mineral of spot A is evidently Quartz.
 
Granite spot B: Feldspar
At first sight on a reflected light image the difference between spot A and B was not self evident.
 
The Raman spectrum of spot B indicates the presence of a Feldspar. Notice that the fluorescence of this white diffusing mineral is very high as can be seen on the original signal before baseline removal. This high fluorescence and the low Raman intensity are responsible for the low signal to noise of this spectrum.
 
Granite spot C: Mica + Quartz crystal
Two crystals have been targeted : a transparent one which seems to be Quartz and a dark one (spot C) presumably a mica Biotite.
 
Raman spectrum shows that spot C is a mica of the Phlogopite family, the dark color indicates Biotite as expected.
 
Raman spectrum confirms the structure of the big transparent crystal above as Quartz.

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