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Mineralogical ClassificationNew potentially new epidote-supergroup species added

3rd Sep 2019 15:52 BSTŁukasz Kruszewski Expert

I have just now added some potentially new epidote-supergroup species to the database. They include the first Cr-dominant end-member.

Ref.:

Varlamov, D.A., Yermolaeva, V.N., Chukanov, N.V., Jančev, S., Vigasina, M.F., Plechov, P.Yu. (2019): Novoe v mineralogii nadgruppy epidota: neobychnye himicheskie sostavy, tipohimizm, KR-spektroskopiya (New data on chemical composition and Raman spectra of epidote-supergroup minerals). Zapiski RMO: 1: 79-99; DOI: 10.30695/zrmo/2019.1481.07 (in Russian, with English abstract)


3rd Sep 2019 17:05 BSTJolyon Ralph Founder

excellent - thank you!

4th Sep 2019 01:04 BSTPaul Brandes Manager

Nice Lukasz - good job!

5th Sep 2019 16:36 BSTŁukasz Kruszewski Expert

My pleasure (: To be sure, at least some of these interesting species may some day appear as new minerals, but this is not that obvious if they are very tiny. This is exactly the reason I've added them. I think the Cr-dominant species is, somehow, most important, as it is first of such type among the supergroup.

5th Sep 2019 20:35 BSTFrank K. Mazdab Manager

Very Cr-rich epidotes have been known for almost 100 years and are quite widely scattered (Hemlo, Outokumpo, Tawmaw [where the name tawmawite was derived], etc.), but the challenge has always been to show that sufficient Cr was stuffed into just one M site to constitute a new species.  Recent papers I've looked at still can't seem to agree on whether Cr prefers M1 or M3, so does this new Russian paper solve that mystery? Or is the Cr content so high that both sites are sufficiently Cr-enriched to bypass the "M1? or M3? or a little of both?" question and make it moot by simply skipping ahead to a {CaCa}{Cr3+AlCr3+}(Si2O7)(SiO4)O(OH) end-member?

edit: still can't do formatting like subscripts and superscripts.  To add that formula above, I had to open javascript console [just to successfully input a "formula from mineral"], input formula for ferriallanite-(Ce) [which gave me most of the correct building blocks], and then had to edit it to conform to what appears above... annoying and time-consuming!
 
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