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Mineralogical ClassificationTantal/Tantalcarbid

20th May 2012 16:24 UTCKnut Eldjarn 🌟 Manager

Can somebody explain why Mindat has mixed native Ta and Tantalcarbid (TaC) under the same heading indicating these as synonyms ? From the literature native Ta and Tantalcarbid seems to be distinct and different substances and should as minerals be defined as separate species.

Knut

20th May 2012 21:54 UTCUwe Kolitsch Manager

Tantal was also used as a synonym for TaC. There is a thread on this on Mindat.

21st May 2012 10:07 UTCjacques jedwab

The situation is still confuse, since a (definitive?) clarification should take into account:

-the date of a publication (before or after the recognition of the Uralian material as a carbide and not as a metallic element);

-the date of the finding by Novgorodova et al. that the Uralian mineral is a solid solution of Nb and Ta carbides;

-the recognition and naming by Novgorodova et al. of jedwabite Fe7(Nb,Ta)3;

-the ascertainment that later authors were aware of these oddities and confusing possibilities;

-the scarcity of reference materials.

I think that the next step should be a careful (re)examination of the materials determined in recent times as metallic tantalum or tantal , taking the above remarks and possibilities into account.

Frankly speaking, I am not very happy with the situation, but the scientific aspects at stake are interesting, especially if one takes into account the existence of other carbides on earth (khamrabaevite, V-carbide from oceanic smoker).

J.J.