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Tantalum

Posted by Jim Burgess  
Tantalum
June 22, 2011 12:18AM
I believe this location should be added for this mineral.


"The most notable deposit of this
kind is Wodgina–Cassiterite Mountain. According
to the statistics on the USGS website, the mine has
produced up to 25% of the world’s primary tantalum
over the last five years."

quote from - Evolution of metallogeny of granitic pegmatites associated with orogens throughout geological time
A. V. Tkachev


- [sp.lyellcollection.org]

also -


[www.australianminesatlas.gov.au]
avatar Re: Tantalum
June 22, 2011 12:50AM
    
Tantalum is a chemical element and produced from tantalum bearing minerals. When an element occurs geologically in a fairly pure state it gets called a Native Element. Native Tantalum is incredibly rare and I believe only observed in microscopic grains. Although Wodgina has produced lots of Ta, none of it was native.

Several kind Australians offered me lots of "Tin" when I was collecting native elements. Again Native Tin is extremely rare but there is one Australian occurrence. Sadly they were offering me cassiterite, a major ore of Tin.

Recently there's been discussion here of the lack of use of "native" when talking of minerals. The insistence on Native Gold. Native Silver, etc. seemed to me a bit obsessive, but apparently not!!!
Re: Tantalum
June 22, 2011 01:26AM
Thanks Rob - I was reading the article referenced, looked up tantalum to see what the heck it was and was surprised to see the Wodgina–Cassiterite Mountain area not listed as a source.

We have a lot of granite around here and I'm starting to pay some attention to it's potential.
Re: Tantalum
June 22, 2011 06:36AM
Molybdenum/molybdenite is another one that seems to get confused pretty often. A lot of people seem surprised that molybdenum is actually a hard metal, as they're used to soft, slippery molybdenite from lubricants.
avatar Re: Tantalum
April 07, 2012 12:08AM
Hi

does anyone know the actual status of Tantalum (Ta) (native element).?
Mindat says: Valid since .... (this - for me - implies, that the IMA approved tantalum as a mineral).
Rob (above) speaks of " native tantalum is incredibly rare" ... and "microscopic grains" - however :

Webmineral says: Not IMA approved and other common references don' t know elemental tantalum as having been approved by IMA.
What's the status ?
avatar Re: Tantalum
April 07, 2012 01:42AM
    
Native Tantalum was described a long time ago, so it ought to be grandfathered as stated at Mindat. However it does not appear on the two lists at the IMA website as valid, grandfathered, discredited, or anything else. The old material was from Avrorinskii Placer, Aktai River, Baranchinsky Massif, Nizhnii Tagil, Ekaterinburgskaya (Sverdlovskaya) Oblast', Middle Urals, Urals Region, Russia, but unfortunately was Tantalum Carbide and is now listed under Tanalcarbide, a valid species. If no one discredited Tantalum as Tantalum Carbide, it still should be a grandfathered species in good standing. There have been a couple of recent mass disceditings and possibly Ta got it then. Of course the original description is wrong but good examples of Ta are posted here at Mindat. If it was discredited, there may be resistance to republishing it as that is a lot of work for something that people know is an honest mineral. However it is not an honest mineral until the IMA says so. (The real definition of a mineral!!!) Perhaps some one closer to the IMA could comment.
avatar Re: Tantalum
April 07, 2012 06:41PM
    
I just noticed that there is a 1983 reference in the IMA list to the discredited Allemontite. If Ta was discredited it it should be on the lists, so I doubt its discrediting. If it was discredited then there is a 50 (?) year wait time before the name can be re used. A "redefinition " might avoid that.

There is also an old 19th century report of native iodine from an Italian volcano, it should be grandfathered as well. Yes!!! It's on the list as "questionable" with its 1897 reference!!! So the silence on Ta is odd.
Re: Tantalum
April 07, 2012 08:00PM
Technically, dubious pre-IMA (1959) species don't require formal discreditation, because part of the definition of a legitimate "grandfathered" species is that it be "generally accepted" (like quartz, gold, etc. - everyone accepts that they are real species). So if a pre-1959 mineral was never "generally accepted", or ceases to be generally accepted, like Iodine (not much evidence ever presented for its natural existence) or Tantalum (turned out to be the carbide), then they sort of ipso facto cease being grandfathered minerals. Nothing wrong with someone submitting a formal discreditation, I suppose, especially if they turn up interesting data worth recording for posterity, but nothing really compels it to be done and I suspect any professional mineralogist worth his salt has far more compelling issues piling up on his desk.



Edited 1 time(s). Last edit at 04/07/2012 08:02PM by Alfredo Petrov.
avatar Re: Tantalum
April 07, 2012 08:09PM
    
So why the IMA silence on Ta? Are people too busy to write up the new material we have posted here at Mindat? Or is it being written up for submission right now? Pavel???.
Re: Tantalum
April 07, 2012 08:25PM
It might just be an oversight, Rob, but I can actually see no particular reason for the IMA to mention it until someone submits a proposal for acceptance and it gets accepted. The "old tantalum" lost its grandfathered status. "New tantalum" hasn't been approved yet (?). Lots of minerals are in this "limbo" world - we know they exist, but they don't appear on "official" lists because there wasn't enough data for an acceptable submission, or they just haven't gone through the procedures. (I once asked a mineralogist who'd published a mineral without approval why he didn't submit it to the IMA, and he said it was because his department chairman didn't think it was a priority and he had lots of other work to do. Not everyone can have the same priorities as systematic species collectors smiling smiley .) Or perhaps it's already been submitted and we just don't know about it yet, but either way Mindat's current status listing it as "grandfathered" is wrong, and should probably be "published without approval".
avatar Re: Tantalum
April 08, 2012 02:12AM
    
Thanks Alfredo. I went in and "fixed" Ta to "published without approval" and left the status as "valid" but wondered about it. The header photo looked convincing so I clicked photos and was disturbed by the second photo. This second specimen was questioned in [www.mindat.org] and then I looked back at the header photo and saw it had an EDS which showed essentially pure Ta. That is surprising as Ta usually occurs with Nb. There has been a small industry of fabricating usually tiny fragments of very rare "native elements" as well as the honest problem of bits of these rare elements in human garbage getting into alluvial systems and are reported as "native elements". I can assure you, the bird shot in my old Similkameen Pt concentrate was not "Native Lead", even though it was collected just like the accompanying Tulameenite. I think Alfredo has tales of "Native Titanium" from falling space junk. Pavel will know the history of this Greenland fragment and why it is so pure.

The Russian publication of the discovery on the Moon seems the reason for a valid status and Published without approval. Perhaps others could comment.
Re: Tantalum
April 08, 2012 02:29PM
The "native" tantalum from Nizhnyi Tagilsk (only locality) has been found to be TaC: Jedwab, J. (1990): Native ruthenium in tantalum carbide concentrates from the Ural Mountains, USSR. Mineralogy and Petrology, 1990, 43, 137-146.

Later named "niobocarbide" by Novgorodova et al.
avatar Re: Tantalum
April 08, 2012 06:13PM
    
Merci Jacques, reference added.
Re: Tantalum
April 08, 2012 07:31PM
    
In our collection (NHM Vienna) we have two "Tantalum" specimens (from Nizhnii Tagil and Aktai River, catalogued in 1910 and 1911, respectively) which are clearly tantalum carbide, judging from their bronze colour.
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