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LocalitiesDiamond Lake, Herschel Township, Hastings Highlands Municipality, Hastings County, Ontario, Canada
27th Nov 2016 00:59 UTCReiner Mielke Expert
27th Nov 2016 01:23 UTCAlfredo Petrov Manager
Normally I'm a stickler for correct naming of species, after analysis, but in the case of something as illogically defined as augite, I'm tempted to say "Who cares?"
27th Nov 2016 12:49 UTCReiner Mielke Expert
Here is another good example http://www.mindat.org/forum.php?read,105,398393,398394#msg-398394 so difficult to kill that not even Mindat wants to do it.
27th Nov 2016 13:31 UTCAlfredo Petrov Manager
Basically we tend to stick to field terms to label these, and I don't think that's necessarily such a bad thing, as long as we keep in mind that that is what's being done. How many purpurites are really heterosites? How many actinolites are really tremolites? How many "piemontites" are really just red epidotes or clinozoisites? How many epidotes are really clinozoisites? How many schorls and uvites are really dravites? How many "ankerites" are really Fe-rich dolomites? What percentage of grey needles are a different sulphosalt than what is written on the label? How many of the "native platinum" photos on Mindat are really mixtures of Pt-Fe alloys? ...and so on and so on. The list of prone-to-misidentification minerals is endless. When a locality has been studied in detail by a mineralogist, we can then probably specify which identifications are wrong. But for unstudied localities (the majority of localities) we can't do that. Then do we demand that photographers pay for an analysis of every amphibole, tourmaline, sulphosalt, garnet, etc etc that they upload or we'll question the photo? I don't know; perhaps we should. But I suppose an extreme step like that would just discourage people from collecting, or uploading photos, and all we'll get from then on will be photos of quartz and pyrite.
I just keep a skeptical "?" in mind when reading any species label, but I can't demand analytical proof from every photographer on Mindat. And what would an adequate level of proof be anyway? Many photographs on Mindat just say "analyzed" on the caption, and I suspect you, Reiner, would be the first to agree that that is a useless statement. We really need to know who analyzed it, by what methods, and what were the actual numerical data, in order to adequately assess the likelihood that the ID is correct. We might have that level of evidence for a few tens of photos, out of the more than three quarters of a million already uploaded to Mindat.
27th Nov 2016 22:48 UTCDoug Daniels
27th Nov 2016 22:55 UTCReiner Mielke Expert
28th Nov 2016 02:08 UTCDoug Daniels
28th Nov 2016 05:54 UTCVachik Hairapetian Expert
28th Nov 2016 11:23 UTCReiner Mielke Expert
28th Nov 2016 11:53 UTCReiner Mielke Expert
29th Nov 2016 15:02 UTCAndrew Debnam 🌟
Andrew
http://www.mindat.org/gallery.php?frm_id=pager&cform_is_valid=1&min=419&loc=&u=&potd=&pco=&d=&showtype=1&phototype=0&checkall=1&loctxt=ontario&keywords=&orderxby=&submit_pager=Filter+Search
Reiner Mielke Wrote:
-------------------------------------------------------
> What proof is there that this is augite? It all
> looks like diopside to me. I know of no verified
> augite from any calcite vein/dyke in Ontario or
> Quebec.
29th Nov 2016 17:22 UTCReiner Mielke Expert
If I can get a hold of a small piece I intend to get it analyzed.
29th Nov 2016 18:00 UTCAndrew Debnam 🌟
29th Nov 2016 18:29 UTCReiner Mielke Expert
This is the same book that attributed green fluorscence to autunite of which there is none, so you have to be wary of that book. If you can send me a tiny clean and fresh piece around 1mm in size that would be great. You can just tape it to the inside of a Christmas card. Maybe best to send me several that size so I can select the best piece for EDS. If you have any other "augites you would like analyzed from Ontario feel free to include them. I will PM you my address. Thanks
29th Nov 2016 19:52 UTCAndrew Debnam 🌟
2nd Dec 2016 21:24 UTCRalph S Bottrill 🌟 Manager
3rd Dec 2016 00:45 UTCReiner Mielke Expert
3rd Dec 2016 01:00 UTCReiner Mielke Expert
Do you have an example of very impure diopside that is not augite? I can't find one, or maybe I should say define very impure.
3rd Dec 2016 03:49 UTCRalph S Bottrill 🌟 Manager
3rd Dec 2016 04:02 UTCRalph S Bottrill 🌟 Manager
3rd Dec 2016 12:22 UTCReiner Mielke Expert
3rd Dec 2016 12:40 UTCPeter Nancarrow 🌟 Expert
As I recall from my dim & distant days in petrology, when the purpose of the a large number of microprobe analyses was to charaterise different members of an intrusive igneous complex for example, assuming no other information regarding actual site occupancy is available, when allocating a pyroxene analysis to its pigeonhole in the Ca/Mg/Fe triangle, the simplistic convention is (was?) that any significant quantities of transition metal cations found were summed with the Fe.
Therefore, although considering Ca/Fe/Mg ratios alone may have placed a pyroxene analysis in the diopside field, adding the total of Ti, Cr, Mn etc ions present to the Fe could shift it into the "augite" field. Of course the charge balance juggling required when significant quantities of Na, Al, Ti, Cr, Mn etc were present added another level of complexity!
So yes, the nomenclature is rather vague, and it's not a definitve answer to the OP from me I'm afraid! Simply all part of the fun of dealing with what I call the "dustbin" mineral groups such as the pyroxenes, tourmalines, feldspars, which can mop up such an enormous variety of elements into their structures.
Pete N.
3rd Dec 2016 12:51 UTCReiner Mielke Expert
3rd Dec 2016 21:21 UTCRalph S Bottrill 🌟 Manager
Reiner, the first RUFF analysis is clearly augite, the second is again borderline between augite and diopside; diopside should have Ca>0.9 for 6 O.
Augites are usually more Fe rich than most diopsides but that doesnt make them dirty and doesnt discriminate the two, its all about Ca.
4th Dec 2016 00:58 UTCReiner Mielke Expert
Is that what they call the 10% rule? Must have been what they were using for this diagram LOL.
4th Dec 2016 12:42 UTCRalph S Bottrill 🌟 Manager
4th Dec 2016 13:13 UTCReiner Mielke Expert
Actually the diagram is based on chemistry and has no validity in terms of the usual accepted IMA definitions, much like the augite-diopside diagram. Either way neither of them make much sense. I find it strange that the IMA is such a stickler for other minerals such as the amphiboles and pyrochlores but so lax in this case.
4th Dec 2016 14:00 UTCAlfredo Petrov Manager
4th Dec 2016 20:37 UTCRalph S Bottrill 🌟 Manager
4th Dec 2016 21:47 UTCReiner Mielke Expert
The diagram is based on phases that exist at room temperature. See diagram below. They are not metastable phases. I have discussed this over the past 7 years on Mindat and find myself coming back to it from time to time. The last discussion led me to conclude that the 50:50 rule applies and not the 10% rule that allowed a mineral called safflorite I. So are you suggesting that in this case the 10% rule applies and that I need to relabel my lollingite samples with more than 10% cobalt, safflorite? Do I call my rammelsbergite samples with 40% cobalt and 60% nickel? safflorite?
5th Dec 2016 04:21 UTCJeff Weissman Expert
With regards to augite - without detailed characterization, diopside is just as good a name as augite. But don't get me started on aegirine-augite or even ferroactinolite/actinolite :-S
5th Dec 2016 12:41 UTCReiner Mielke Expert
The first diagram was not prepared using only synthetic phases but mainly natural ones supplemented by synthetic ones. Also the first one does not represent stability ranges but simply known compositions at room temperature and is by no means comprehensive. The second was creating using a microprobe and polished sections as you suggested and the analyses do not represent mixtures. Although in many cases these compositions occur in zones within a single crystal.
If you want to know the details of these diagrams I suggest reading the paper these came from http://rruff.info/doclib/cm/vol11/CM11_150.pdf
or you can just take my word for it.
5th Dec 2016 14:48 UTCJeff Weissman Expert
5th Dec 2016 16:09 UTCReiner Mielke Expert
The reason I brought it up was the "10% rule". I have no interest in discussing safflorite further as it is a dead horse as far as I am concerned. I will stick to the IMA 50:50 standard for the diarsenides. As for augite, it is not up to us to change things, we will just have to live with the craziness.
6th Dec 2016 11:14 UTCRalph S Bottrill 🌟 Manager
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Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 26, 2024 03:07:51