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Improving Mindat.orgAwaruite

31st Dec 2005 00:43 UTCFranz B. Schweiger

The correct crystal system is: cubic, with Pm-3m (see Strunz Mineralogical Tables, 2001, p. 42), Auricupride structure, this is stemming from Bayliss, Can. Min. 1990, p.751. Sorry I can't get the original paper - I hope that Bayliss' 'Awaruite' is really from the type locality in New Zealand, and not, for example, from Josephine Co. or another place, so that the name could be rather out of place...

Franz

31st Dec 2005 01:00 UTCFranz B. Schweiger

I forgot the correct structural formula: It is Ni3Fe. (So-called 'Ni2Fe' could also be crystallized in this structure, so it would be circa (Ni2.67Fe0.33)3Fe.- but I don't know this with surety!)

Franz

31st Dec 2005 04:05 UTCAlan Plante

I have the following references for this mineral:

- Dana 7th, 1: 117 (1944)

- N.Jb.Min.Ah., 107: 241 (1967)

- Min. Mag., 40: 247 (1976)

- Min. Mag., 43: 647 (1979)

- Can. Min., 28: 751 (1990)

Fleischer's Glossary and Dana 8th agree that it is Isometric. I have it as "Iso., hexoctahedral, Fm3m."

Cheers!

Alan

PS: Blind note to David and Marco. - This is one of the "NJMA" references I was trying to hunt down the date for the other day... :~}

31st Dec 2005 10:46 UTCFranz B. Schweiger

You say "it has Fm3m" (same as Fm-3m). I can't believe that, because, then Awaruite and Nickel should not be different mineral species (both would have fcc lattices, formulae (Ni,Fe) resp. Ni), and one of the name should be discredited (usually the newer one, that's nickel).

So I think the solution to the problem can be found in Bayliss's paper, who knows?? ( I still think it's Ni3Fe with Pm-3m, believing in Strunz and Nickel - fitting name, by the way)

And, there's a similar problem with kamacite: one could think it's alpha-Fe with some Ni (= mineral iron), but one paper has the title "Kamacite...superstructures..." (of Ramsden and Cameron, 1966, Am. Min. 51, 37-55), so it could also have another formula than iron, can anybody have a look into this paper?

Cheers

31st Dec 2005 11:45 UTCMarco E. Ciriotti Manager

Awaruite is cubic: 3.59 3.59 3.59 90 90 90

Cell Volume : 46.26828

Space Group : Pm-3m (221)

References:

American Mineralogist 76 (1991), 1356

2. Canadian Mineralogist 28 (1990), 751

3. Mineralogical Magazine 43 (1980), 647

4. American Mineralogist 45 (1960), 450

5. Handbook of Mineralogy (Anthony et al.), 1 (1990), 38

6. Canadian Mineralogist 38 (2000), 585

7. Journal of Alloys and Compounds 343 (2002), 192 .

31st Dec 2005 12:05 UTCMarco E. Ciriotti Manager

About awaruite space group, please note, that the crystal structure of the natural phase is unsolved, at today.

Here some other references:

Palache C., Berman H., Frondel C. (1944)

* Dana's system of mineralogy 7th ed., I, 117-119

Berry L.G., Thompson R.M. (1962)

* Geol.Soc.Amer.Mem., 85, 13

Ramdohr P. (1969)

* The ore minerals and their intergrowths 3rd ed., 356-357

Challis G.A. (1975)

* Mineral.Mag., 40, 247-251

Ahmed Z., Bevan J.C. (1981)

* Mineral.Mag., 44, 225-230

Bayliss P. (1990)

* Canad.Mineral., 28, 751-755

31st Dec 2005 15:49 UTCAlan Plante

I think the "Fm3m" is *another* typo in Dana 8th... :~}

If it were not, I would tend to agree with Franz - that it is just nickel with a bit of Fe substituting for Ni here and there.

But the more I read about the supposed naturally occuring alloys, the more I wonder if they should be considered separate species... If it were up to me, I think "awaruite" would be demoted to a sort of polytype of nickel! :~}

Cheers!

Alan

31st Dec 2005 21:34 UTCFranz B. Schweiger

You say it would be a sort of polytype of Nickel. I don't agree with that, because, if Awaruite was Ni3Fe, with Pm-3m, there would have to be always iron in it, as in the formula, so you can't say it is a 'Nickel' polytype. A Ni3Ni can't exist because then all atomic positions would be the same, and it was Fm-3m with fcc-lattice.

But that leads to the question if minerals with different ideal formulae should have the same names at all (look at nigerite/magnesiotaaffeit and so on, what about the humite/chondrodite etc. series?!...)

Cheers

31st Dec 2005 22:17 UTCJim Ferraiolo

Franz,

Nigerite (actually now ferronigerite-2N1S) and magnesiotaaffeite do not have the same compositions. This whole group was redefined in 2002 as separate polysomes. The paper is available on-line at the IMA website

31st Dec 2005 22:31 UTCChester S. Lemanski, Jr.

I added in all of the above references; however, there seems to be a disparity in the numbering sequence of the Min. Mag. volumes and their respective years of publication.

Chet

6th Jan 2006 00:05 UTCFranz B. Schweiger

So in the end someone should come and correct the crystal sytem of Awaruite, too: It's cubic, that's for sure even if all other things seem not to be sure about awaruite...

Cheers

(The mistake seem to stem from Lapis-Mineralienverzeichnis?!)

6th Jan 2006 10:21 UTCMarco E. Ciriotti Manager

Fixed: cubic.

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