Representative data available on the Mineral Spectroscopy Server.

Visible Spectra: higher resolution

Spectrum of the amethyst and citrine zones in a 1.0 cm thick slice of the ametrine variety of quartz (Fe-containing SiO2) from the AnahÝ mine, Bolivia.

These data were obtained with a home-made diode-array spectrometer system built from a EG&G PAR detection system with Si and InGaAs arrays, an Acton triple grating spectrometer and Oriel Q-housing tungsten and xenon lamps. They were obtained at 1 nm resolution formerly with a 386 PC system and now with a Pentium PC system.

For more on ametrine, click here.   

Visible Spectra: lower resolution


Absorption spectrum of the amphibole, tremolite, Ca2(Mg,Fe)5Si8O22(OH)2, from Mt Bity, Madagascar, dominated by broad absorption from Fe2+ in the M4 site near 1000 nm and 2450 nm. Weaker broad features near 950 and 1150 nm are from Fe2+ in the M(1) site. Strong, narrow bands from OH are prominent near 1400 nm and weak near 950 nm.

These data were obtained with a Cary/Varian 17I grating spectrometer optimized for the near infrared. They were obtained at variable resolution (2-5 nm), output on chart paper and digitized by hand on a Tektronix digitizing tablet.  

Infrared Spectra

  Garnet Spectrum

Spectrum in the OH region of grossular garnet (tsavorite variety - Ca3(Al,V)2(SiO4)3 ) from Tanzania, showing absorption from multiple OH sites in the 3600 cm-1 region.

These data are commonly obtained at 2 cm-1 resolution at room temperature (23░C) with a CaF2 beam splitter, a quartz-halogen tungsten source, and an InSb LN2-cooled detector.  We use a Nicolet 860 FTIR.  Previously, we used a Nicolet 60SX FTIR and, before that, a Perkin Elmer 180 dual-beam dispersive IR. 


Raman Spectra

Raman spectrum of slabs of spodumene in two orientations.  These data were obtained at 785 nm from a laser diode source on a 1.2 mm diameter spot with our former Kaiser Optical Systems HoloProbe 785 system and a probe head from EIC Laboratories. 

We now work at 514.5 nm, 532 nm, and 783 nm with a Renishaw microRaman system.

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updated 15-Aug-2015