Hi Maite,

I haven't seen the lack of agreement of stibnite mode assignment that you describe. Although I've only just looked at Raman studies of stibnite mineralogy since you posted your question. If possible, could you forward specific references that illustrate the inconsistencies? Below is a recent reference of mode assignments for stibnite with polarized Raman laser (632.8 nm laser) and other sulfides that may help (also see references therein for other papers). RRUFF.info also has several Raman spectra for multiple wavelengths and they seem consistent to me.

Kharbish, Sherif, Eugen Libowitzky, and Anton Beran. "Raman spectra of isolated and interconnected pyramidal XS3 groups (X= Sb, Bi) in stibnite, bismuthinite, kermesite, stephanite and bournonite." European Journal of Mineralogy 21.2 (2009): 325-333.

Aaron

Hi Aaron,

Thanks for the answer and for the reference.

I have downloaded this morning several articles (included this one) at work and I have more or less the coincident Raman spectra of Stibnite.

The last day I have checked different Raman spectra of stibnite in RRUFF website and I have seen that one of the spectrum had two additional bands around 375 and 716 cm-1. I have checked that the band at 375 cm-1 appears in other spectra from the literature but nothing about 716 cm-1 band (weak one). However, this last band is not so important because with the rest of the Raman feature it is enough for the good Raman assignation.

Thanks again for your contribution.

Maite

No problem. If I happen to find out more info about the 375 cm-1 and 716cm-1 peak I will forward on to you.

Was the 'odd' spectrum you noted in RRUFF the R120137 sample? One possibility is that there is some substitution of the Sb site causing the additional bands to appear. The note on the collectors (Benjamin Schumer) label stated that it is a Se-bearing stibnite. But going back to your original question, I don't know what those modes might be. If those bands are caused by substitution of another element, it would be interesting to see a single crystal/Raman study to see which crystallographic distortions may occur to induce such changes in the Raman spectrum.

Lorandite (TlAsS2) has a peak at ~375 cm-1 and ~735 cm-1. Maybe there is a correlation?

The other Raman entry (R050016) that shows the weak 375 cm-1 and 735 cm-1 has trace As in it, but that doubt that such a small amount would contribute significantly to the Raman spectrum.

I hope you find someone who has a better answer for you!

Cheers,

Aaron

Maybe arsenic can contribute to these Raman bands, who knows.

Nevertheless for me it is enough to have the rest of the bands (stronger) to assign to stibnite. I am not analysing individual crystals of this sulphur, I have this sulphur as residue of gunshot particles, in areas where Sb and S appear, so this help me to finally say if it is or not Sb2S3.

Thanks again .

Cheers,

Maite