minerals of this section are olivine fayalite, augite, feldspar
orthoclase, altered olivine to iddingsite and magnetite.
in area 3 is the iron rich olivine fayalite.
small green crystals (area 2) spread everywhere in this rock are augite.
component of this phonolite rock is the feldspar orthoclase.
Phonolite area 4 Iddingsite
The red crystal in area 4 exhibits a low signal to
noise Raman spectra. No reference spectrum has been found for
comparison. Its color suggests an olivine crystal altered to Iddingsite,
an hydrous silicate of Mg and Fe.
The big crystal in area 5 is again the feldspar orthoclase.
Area 6 is augite.
Opaques minerals: magnetite.
view of the section. The opaque mineral has a high reflectance and
appears thus white in this plane polarized image.
Above is the
reflection image between crossed polars. The material in area 7 is black
The power of the helium neon
laser has been limited by a grey filter of absorbance 0.6 to avoid
oxidation of the opaque minerals. The blue spectrum is magnetite. If the
full power laser is used, the material is oxidized and gives an hematite