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Mineralogical ClassificationDiscreditations IMA 2006-C

14th Feb 2007 21:19 UTCMarco E. Ciriotti Manager

Reference:

â€¢ Burke, E.A.J. (2006): A mass of discreditations of GQN minerals. Canadian Mineralogist, 44, 1557-1560.

14th Feb 2007 22:39 UTCChester S. Lemanski, Jr.

Should we have someone volunteer to tackle this monstrous list of discreditations for correction of our files in Mindat? It could be divided at points in the alphabetical sequence for several of us to attend to the required changes. What do we do??

14th Feb 2007 22:52 UTCMarco E. Ciriotti Manager

Yes Chester, this week I am very busy, but the next I can provide, for example, the page 1558.

15th Feb 2007 15:43 UTCJim Ferraiolo

Chet, I can work on some of these as well, however you want to divide them up.

15th Feb 2007 15:53 UTCChester S. Lemanski, Jr.

Marco took page 1558, I'll take page 1559, leaving page 1560 for you, if that is acceptable (it's about a 2/3 page). Thanks Marco & Jim.

15th Feb 2007 16:35 UTCErnst A.J. Burke

Sorry for giving you so much work!

15th Feb 2007 17:33 UTCChester S. Lemanski, Jr.

Dr. Burke,

It is very welcomed!!

16th Feb 2007 04:33 UTCMr. Gail E. Dunning

Dear Dr. Burke,

Thank you for the good "Housecleaning" of the current list of minerals. It certainly needed it! I would suggest that this process be done on a regular basis to keep the list of valid mineral names accurate.

In my list of mineral names I have several that are listed as "questionable". Has the CNMMN any recommendations on whether these are still "questionalble" because of the lack of adequate data or have they meen rejected before. These minerals include:

ARZAKITE

CHALCOALUMITE

CLINOBARYLITE

CLINOTYROLITE

DOMEYKITE

MONTANITE

PARANATROLITE

Thanks for your attention and good work,

Gail Dunning

16th Feb 2007 09:45 UTCErnst A.J. Burke

Dear Gail Dunning,

In spite of the recent mass discreditation of GQN minerals, there still is a number of Q and N minerals, for the simple reason that no additional information is available to allow a decision on them.

Regarding your list:

Arzakite = N, published without approval, but seems to be a valid mineral

Chalcoalumite = G, grandfathered valid mineral

Clinobarylite = A, approved by CNMNC as 2002-015, the subsequent change in symmetry does not alter the category

Clinotyrolite = N, published without approval; according to the recent paper in American Mineralogist 91 (2006) 1378-1384 probably identical with tyrolite-1M; tyrolite, originally described as orthorhombic, is monoclinic with two polytypes, -1M and -2M.

Domeykite = G, grandfathered valid minerals (plural), as we also have a domeykite-beta

Montanite = Q, questionable, but no data available beyond the original inadequate description

Paranatrolite = A, approved by CNMNC as 1978-017, but our zeolite subcommittee has given it doubtful status in 1997, separate species status is debatable.

16th Feb 2007 12:36 UTCJim Ferraiolo

A couple of questions concerning the GQN list:

Is kamacite is nickel-rich iron, shouldn't taenite be considered iron-rich nickel?

Concerning calciovolborthite (cribbing from an earlier thread):

According to Bass & Zefiro ("Mineral nomenclature : status of calciovolborthite and tangeite", NJMM 1994, 205-208):

A proposal was sent to the IMA-CNMMN to discredit calciovolbothite and accepted tangeite as having the cooposition CaCu(VO₄)(OH), with a type locality of Tange ravine, Tyuya Muyun, Ferghana, Turkestan.

The paper gives these points:

1. Calciovolborthite was not discredited by the IMA, due to lack of a type specimen (type locality is Friedrichsroda, Thuringia).

2. All 'calciovolborthite' specimens from Friedrichsroda examined by Giullemin in 1956 had Ba in place of Ca, and was described as a new mineral - vesignieite.

3. No minerals has been found at Friedrichsroda having the composition CaCu(VO₄)(OH).

4. Tangeite, with the composition CaCu(VO₄)(OH) has been described from Tange ravine, Tyuya Muyun, Ferghana, Turkestan.

5. Tangeite was accepted by the IMA as having the above composition.

Because of this, Basso & Zefiro state " As a consequence the name calciovolborthite, no longer synonym of tangeite, identifies the mineral from Friedrichsroda with the composition given by Credner (1848)", the original description of calciovolborthite. The composition given by Credner, using the analysis given in Dana 6, works out to CaCu₃(VO₄)₂(OH)₂.

Was this last point not considered due to lack of type material?

20th Feb 2007 13:17 UTCErnst A.J.Burke

Jim,

- You may have a point with taenite.

- The 1994 paper and the current discreditation of calciovolborthite are sufficiently clear. There is no original material available, so what to do??

20th Feb 2007 14:06 UTCAlfredo Petrov Manager

Taenite would have to be Ni-dominant in order to be "iron-rich nickel", but most references list taenite as Fe-dominant. Which analysis is correct?

20th Feb 2007 16:14 UTCMarco E. Ciriotti Manager

I think that the formula of cubic taenite can be gamma-(Ni,Fe) or gamma-(Fe,Ni). Structure on natural phase unsolved (if I well remember!).

Tetrataenite, tetragonal is FeNi .

20th Feb 2007 16:27 UTCAlfredo Petrov Manager

Surely gamma-(Ni,Fe) and gamma-(Fe,Ni) cannot be the same species? Maybe it needs to be considered a series.

20th Feb 2007 16:41 UTCMarco E. Ciriotti Manager

Yes Alfredo, I agree...

20th Feb 2007 16:56 UTCJim Ferraiolo

Thanks, Ernst.

Just wanted to clarify the calciovolborthite discreditation.

27th Feb 2007 00:09 UTCAndrew Locock

With regard to the identity of taenite:

Awaruite is defined as the Ni-dominant alloy (Ni,Fe)

with space group Fm3m and cell dimension ~3.55 angstroms.

Taenite is the Fe-dominant alloy (Fe,Ni) with

space group Fm3m and cell dimension ~3.59 angstroms.

Both are isostructural with the phase that metallurgists

call austenite (a ~3.61 angstroms), or gamma-iron. For

reference, pure Ni has a ~3.52 angstroms in the same

space group.

Tetrataenite is an ordered tetragonal phase (cf. American

Mineralogist, 65,624-630, 1980), with a ~2.53, c ~3.58

angstroms.

Regards,

Andrew

27th Feb 2007 01:06 UTCFrank Keutsch Expert

I understand taenite as a distinct mineral from iron, as native iron is Im3m and thus clearly is structurally different.

As you say nickel itself, like Awaruite, is Fm3m. How come then Awaruite and Nickel are distinct minerals? Seems like there would have to be some ordering...

Thanks,

Frank

27th Feb 2007 08:18 UTCPeter Haas

"How come then Awaruite and Nickel are distinct minerals? Seems like there would have to be some ordering... "

Maybe a mixing gap instead ?

27th Feb 2007 22:18 UTCAndrew Locock

Cubic taenite is iron dominant, awaruite is nickel-dominant,

and thus the minerals differ.

27th Feb 2007 22:29 UTCAlfredo Petrov Manager

No, Andrew, the question morphed into why are not awaruite and native Ni the same species? Both presumably Ni-dominant.

27th Feb 2007 22:37 UTCFrank Keutsch Expert

My question is how cubic awaruite is different from cubic Ni, both have the same space group and roughly the same unit cell size. Clearly awaruite is more than a disordered Fm3m (Ni,Fe) otherwise it would be the same mineral as Ni.

I have not had time to read up on it, but my guess is Awaruite is something like an ordered Ni3Fe phase, and thus the distinction between Awaruite and Ni is similar to Cu3Au and Cu...

I am also not sure how taenite fits in (ordered Fe3Ni or a disordered gamma-(Fe,Ni))...

Thanks for any help with this.

Edit: I did not see that Alfredo had posted the same question more concisely already. Apologies...

Frank

27th Feb 2007 23:39 UTCErnest H. Nickel

It seems that awaruite and nickel do not crystallize in the same space group. It is generally agreed that nickel has space group Fm3m, but awaruite has space group Pm3m, with Fe and Ni ordered in the structure (see Bayliss: Can. Mineral. 28, 1990, 751-755).

28th Feb 2007 23:00 UTCFrank Keutsch Expert

Thanks for that information. I was going by the handbook of mineralogy, which has Awaruite as Fm3m, but the reference clarifies this question (and some other ones I had) nicely...

Frank

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