Raman Peridotite from Italy.
Wide field thin section of this rock.
Minerals Schorlomite - Enstatite - Forsterite found by Raman.Peridotite area 1: brown cubic crystal.Crossed polars view and plane polarized images.
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Area 1 is a brown cubic ( always black in LPA view ) material. The Raman spectrum indicates that it could be Schorlomite, a mineral from the garnet family. Another specimen (spot 4) has also been recorded with a completely similar spectrum. |
Peridotite areas 2 and 3.
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Area 2 is the low birefringence
pyroxene enstatite as indicated by the Raman spectrum. Some other
enstatite spectra are given in areas 5 and 6 below. In the plane polarized view, enstatite is slightly pinkish-brownish colored and green to pink pleochroic.
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The forsterite crystals (olivine) are ubiquitous in this section. Two representative spectra are given (3 and 7). Forsterite exhibits high birefringence colors in LPA. |
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As Raman is recorded on a 30µ thickness
section, the problem of the interference by the Raman spectrum of the
glue has been examined. Hopefully, the glue used for the section
manufacturing is not fluorescent.
The glue Raman spectrum is shown in the figure on the left. To view the impact on the spectra of the minerals, an attenuated spectrum has been added to approximately match the peak around 1600 cm. Small glue peaks are thus present in the forsterite spectrum (black curve on the left figure) but they are small enough so that the minerals spectra could be easily interpreted. |
Peridotite areas 4 to 7.Area 4 is again the cubic brown crystal suspected to be Schorlomite.
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Crystals 5 and 6 are Enstatite. Area 7 is the forsterite. |
