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Improving Mindat.orgPlatinum, isoferroplatinum, tetraferroplatinum and they photo

6th Nov 2005 19:45 UTCPavel Kartashov

Dear friends!

There is very strange situation with native platinum minerals exist on the database! All photos (9) are concentrated on the page of native platinum Pt. But noone from this picture not belong to exactly mineral platinum Pt! Part of them ( 5 from Konder massif and 1 from Kamchatka peninsula) represent isoferroplatinum Pt3Fe and must be transfered to page of this mineral specie (where is absent any photo). Photo of nugget from Is river (Ural) represent tetraferroplatinum PtFe. Rest two photos of specimens from Colombia and Alaska also belong to this two minerals Pt3Fe (more probably) or PtFe (less probably). All these nuggets are "native platinum" but dont contain mineral platinum Pt!

The same situation with locality list (126 points of mineralization). Localities of native platinum Pt compose much less than 5% of this list.

It is necessary to do something to improve this situation. For example organize two different pages: A 'native platinum' of unspecified composition, and B mineral native platinum Pt with its varieties (rhodian, palladian etc). Polyxen isn't variety of platinum - it is intergrowth of iso-, tetraferroplatinum and other minerals of PGE (osmium, malanite, cooperite etc).

And in any case photos of isoferroplatinum from Konder (composition of which is well known, analysed many times, and published in many papers) must be transfered to isoferroplatinum page.

7th Nov 2005 00:35 UTCJolyon Ralph

This is very interesting, and I think we are going to need to work hard to correct this - thank you very much for raising this to our attention.

Jolyon

7th Nov 2005 13:32 UTCalfredo

I don't think isoferroplatinum can be distinguished from Fe-bearing platinum without structural work, can it? Is it possible to identify such phases merely by looking at a photo? Or is Pavel implying that ordinary native platinum does not occur at the localities mentioned, so therefore they must be Pt3Fe or PtFe? At least with regard to Colombia and Alaska I think that is doubtful.

7th Nov 2005 15:58 UTCPavel Kartashov

Dear Alfredo!

Mineral platinum Pt don't contain iron. This is main feature which differ it from iso- and tetraferroplatinum. Nonmagnetic Fe-bearing platinum is isoferroplatinum. Magnetic one is tetraferroplatinum or intimately intergrown iso- and tetraferroplatinum in ratio close to 1:1 with mean composition Pt2Fe. Thje last often are found in placiers of Chukotka and Middle Ural, also in some small mafic massifs of Norilsk group.

Platinum Pt, in the difference from Fe bearing Pt minerals, forming by another way. Mainly it is hydrotermal or chemical sedimentary origin. Main impurities in platinum are Pd, Rh, Au, Hg and Pb but Fe, Cu, Ni content usually is below detection lewel of microprobe.

99.9 % of platinum minerals in Pt placiers represented by Fe bearing minerals derived from basic and ultrabasic rocks without chemical changing. But in some placiers of countries with humid climat, in lateritic crust of weathering, in caperocks of salt domes, in uraniferous black shales we found Fe-free platinum of chemogenic origin. Usually it is microsize, but I have 1-1.5 mm size palladian and rhodian platinum. So if you have 5 mm nugget from placier - check it by magnite. If it is magnetic, you are happy and have tetraferroplatinum (it is more rare). If it nonmagnetic - you have usual isoferrroplatinum.

Structural works here isn't necessary, only common sence is. :) Native platinum Pt is too scarce, you don't meet it on market.

All is quite simple with determination of native platinum minerals from photos: I know how platinum Pt looks. I'll make soon photos of palladian platinum nuggets from Guinea and upload them. And you will able to feel a difference. This wath the reason why I'd visited platinum page.

7th Nov 2005 17:43 UTCFrank

Dear Pavel,

I have often wondered about teh same. However, I think the better point then saying there is not Fe in platinum is exactly how much is miscible in platinum without affecting the crystal structure, as there has to be some limited miscibility. Is it 0.001%, 1% 10% That would be interesting as I have analyzed a lot Pt-nuggest with highly variable amounts of Fe, but many close to Pt3Fe...

I would appreciate if you had some quantitative numbers for this as it would help me!

All the best,

Frank

8th Nov 2005 16:10 UTCPavel Kartashov

Dear Frank!

All is quite simple if we'll take usual binary system Pt-Fe. Isoferroplatinum Pt3Fe have ideal composition Pt 91.29, Fe 8.71 %. Tetraferroplatinum PtFe one is Pt 77.74, Fe 22.26 %. But pure tetra-FePt with the end member composition is qute rare (by the way it has specific dark yellowish-grey colour). More often we meet micromixtures of iso-FePt and tetra-FePt in different proportions. For some deposits mixture of Pt3Fe and PtFe in proportion 1:1 and mean composition Pt4Fe2=Pt2Fe is very characteristic. So we can to divide iso-FePt and tetra-FePt fields of predominance on composition Pt 87.48, Fe 12.52 %. Tetra-FePt predominate in alloys with Fe content in range 12.5-22.2 wt.%, iso-FePt in range 8.7-12.5 wt.%. Iron content in platinum Pt is nigligible, but we can assume the level below 0.5 wt.% Fe for orientation.

In nature, especialy for deposits derived from basic rocks, we have very often some admixtures of Cu and Ni in tetraferroplatinum. But when their content don't exeed 3-4 wt.%, we can assume that we have copper, or nickeloan, or copper-nickeloan tetraferroplatinum. When one of this elements content is over 4-5 wt.%, we can state transition to tulameenite or ferronickelplatinum. Tulameenite has well visible pinkish colour. Isoferroplatinum usually don't contain significant admixtures of Cu and Ni.

I am hope, I'd answer your question.

Kind regards,

Pavel

24th Nov 2005 19:03 UTCPavel M. Kartashov

Dear friends!

Here is reference for isoferroplatinum from Konder massif in English:

Nekrasov I. Ya. e.a. Compositional variations in platinum group minerals and gold, Konder alkaline-ultrabasic massif, Aldan shield, Russia, - Canadian Mineralogist, 2005, v.43, N2, pp. 637-654.

On the first page (p.638) of this article you can read about isoferroplatinum. Additional references on structural investigations of it by A.G. Mochalov (in Russian) are given.

On Fig.2 (p. 641) you can see compositional variations of "cubic nuggets of platinum (6) locally coated with a films of Cu-bearing gold". All theyr compositional points are on the bottom of the diagram close to 28 at.% of iron. Such composition is almost ideal isoferroplatinum.

So, I am think, that all 5 photos of cubic crystals of "platinum" from Konder massif ( picshow.php?id=8357, =10635, =20954, =26753 and =33135) must be moved from platinum Pt page to isoferroplatinum Pt3Fe one.

By the way, for variety Ferroan Platinum on the database formula Pt3Fe is given. It is identical to isoferroplatinum one. This is sharp error. For unordered platinum/iron alloys it must be given as (Pt,Fe).

Thank you.

Pavel

24th Nov 2005 19:27 UTCalfredo

Dear Pavel,

Do disordered Pt-Fe alloys exist? Or rather, can you be sure that all specimens of isoferroplatinum composition are ordered? If so, then the platinum variety "ferroan platinum" probably doesn't exist, and we can kill this name.

I enjoyed your fotos of the palladian Pt from Guinea - they somewhat resemble some of the specimens from Brazil, which might also have been biologically precipitated.

Cheers,

Alfredo

25th Nov 2005 14:25 UTCPavel Kartashov

Dear Alfredo!

Disordered Pt-Fe alloys exist of course. But it isn't obligatory theyr composition must be close to (Pt.75Fe.25). Iron content may be lower or higher than 8-9 wt.%. It may be 5-6 or 15-17. It is possible, that maximum such compositions will fall on 12.5 wt.% of iron and correspond to (Pt.67Fe.33). But in any case disordered Pt-Fe alloys spread in nature much more rarer than ordered intermetallic phases and theyr mixtures. Frequency of their ocurrency ratio is about 5:95, may be lower.

And in any case, ones must to look for disordered Pt-Fe alloys not within nuggets, but within micro size inclusions into rock forming minerals. And such rocks must be formed in tempering conditions. For ultrabasic rocks such conditions is almost nonsence, and they are very rare for basic rocks with sufficient Pt contents. Anoter way of disordered Pt-Fe alloys formation is low temperature fast chemogenic precipitation, in such conditions ordering don;t play significant role. But as I wrote before in such conditions iron present in oxidized form and don't take part in formation PGE minerals. In this process took part metals with more high than hydrogen electrochemical potential - Cu, Ag, Au, Pb, Hg and PGE.

So if we have sub cm platinum crystals or nuggets, they are consist from ordered phases without any variants. Of course if somebody don't try to heat them and temper then.

I see the situation as next, finding of disordered Pt-Fe alloys need in confirmation, not vice versa.

Yes, this Guinea specimens had formed the same way as Brazilian platinum and palladium micronuggets. By the way in Jurassic times Guinea and Brazil were so close each to other as Belgium and Luxemburg now :).

By the way, about varieties. In the database absent gold varieties with exeption Argentoan Gold and Goldamalgames. I'd try to upload palladian gold from Paramangui and copper-bearing gold from Ichetui, but wasn't able. Do you can to open Pd- and Cu-bearing gold pages?

And how for you rhodian platinum xls from Vilyui photo is? I am very proud with this picture - it is the best from 23 attempts to photograph it! For all that they too small...

Kind regards,

Pavel

29th Nov 2005 02:42 UTCalfredo

Thank you Pavel!

Your investigations bring up an interesting point; Perhaps "Isoferroplatinum" should never have been accepted as a new species, because it is the same material as most of the nuggets from Colombia, called "platinum" for a couple hundred years already, so the old name should have priority, and then the "new" species requiring a new name would be the other structure, Fm3m, your iron-free palladian and rhodian specimens.

Cheers,

Alfredo

1st Dec 2005 18:44 UTCPavel M. Kartashov

Dear Alfredo!

It seems to me, that it isn't good idea to change names of platinum and isoferroplatinum now. With such changing of names too many misunderstandings will appear.

Kind regards,

Pavel

21st May 2016 19:44 UTCHERNAN VILLEGAS

Good morning, I'm an industrial engineer and work in R & D, in recent years I have dedicated my work to the development of electrochemical equipment for the treatment of contaminated water, this technology uses reactors inside which have titanium electrodes coated with ruthenium-iridium and that circulate energy among them decompose more recalcitrant contaminants present in the water, this technology is known as "advanced oxidation"

Two years ago to start a personal research, magnetic black sand recirculate pleasures of rivers in western Colombia, the interior of the reactor, in order to release platinum alloys of iron and others.

In two years I have had some results and share them want to have, just as I have questions about the different alloys of platinum, I have studied the subject of patino from the analysis of Berzelios published in 1840 and other researchers until today, but I have doubts and would help if it's possible. Thank you

21st May 2016 20:37 UTCŁukasz Kruszewski Expert

Very interesting matter, Pavel - thanks for adding. It is somewhat frustrating, because it seems to me that without at least a chemical analysis it is hard to differentiate the above species, anyway.

21st May 2016 21:04 UTCHERNAN VILLEGAS

good afternoon to all, a question, the iron content of tetraferroplatinum is almost 20%, making it magnetic, the isoferroplatino has only 8% iron, I wonder if the new neodymium magnets can capture this isoferroplatino?

22nd May 2016 00:27 UTCTony Peterson Expert

I have changed my Konder specimen to isoferroplatinum.

Tony

22nd May 2016 01:25 UTCPavel Kartashov Manager

Hi Hernan,

all feroplatinum alloys attracted to neodimium magnets. AB species (tetraferrolpatinum, ferronickelplatinum and tulameenite) are most magnetic and can to be extracted by usual magnet from radio dynamic. Polyxene has intermediate magnetic properties. Isoferroplatinum is least magnetic - usual magnet don't attract it, but neodimium magnet do it.

Real native platinum is nonmagnetic together with native palladium and hexagonal OsIrRu alloys.

With set of three magnets with different strength I easily divide this probe

to 4 fractions: 1. AB species and strong magnetic polyxene close to composition Pt₂Fe, 2. low magnetic polyxene transitive to isoferroplatinum, 3. isoferroplatinum and 4. gold with admixture of hexagonal OsIrRu alloys.

But it is impossible to select from river sand significant quantity of ferroplatinum by even very strong magnet. Being magnetic ferroplatinum attracted to magnet, but only from very short distance. The main problem is, how you will extract minor ferroplatinum component from magnetite rich sand. Abundant and stong magnetic magnetite will blocks surface of your magnet from close contact with rare ferroplatinum grains. Besides that, magnetite after contact with neodimium magnet will be magnetized with formation of clods.

22nd May 2016 21:12 UTCHERNAN VILLEGAS

Good afternoon Mr. Pavel; thank you very much for taking my question, with great desire respect him know a little of the context in which I find myself, I hope not bother with this; I am in the city of Cali-Colombia located to the west of the country and what we call Choco geografico is an area between the border of Panama and of Ecuador, here platinum was found by the Spaniards in the año1750, geologically it is mafic-ultramafic one area, the area is a vast rainforest bANANA by countless rivers that drain the waters from the western mountains to the Pacific ocean,

Mining is abundant in gold mining almost all rivers, but 90% is mostly artisanal work performed by black communities and native Indians, three or four dredges American companies on the river san juan, extracting gold -platinum.

Of rivers sand for construction of housing and roads is extracted, this sand to dry in the sun, you will appreciate some flakes 0.5 mm or slightly less gold (not pyrite) but passing Neodymium magnets lot of material is captured ferromagnetic, this made me think about the platinum, given that here in my country paradoxically almost nothing is known about this material and not as ejected even sold not know recognize it at the source.

After much reading, I found some information such as the concentration in Colombia platinum PGM is 91%, 1% Pd, 1% Ir, 1.5% Rh, something osmium-iridium, and between 5% to 8% Fe this is an advantage over the composition of the Urals, South Africa, Canada or Alaska.

So I decided to put the magnetic concentrate in aqua regia, are particles of 1 mm, and follow the process known heat for hours, evaporated to remove nirico acid and precipitate with ammonium chloride, now is not how to test if what I have is hexachloroplatinate ammonium.

Since many chloro complexes are formed, and be sure that no Pt2, and should be Pt4 to precipitate all?

I have attached pictures of the sand, and precipitate

I hope not molestale for this long post,

A greeting

Hernan

22nd May 2016 21:18 UTCHERNAN VILLEGAS

Mr Pavel: Sand photo

22nd May 2016 22:45 UTCPavel Kartashov Manager

Hernan,

your sand is still to "grey" - it contains a lot of light minerals (I recognize garnet, zircon and quartz). You may to try to clean it from magnetite - move strong magnet on distance 3-4 cm over sand. In such case only very strong magnetic particles will attracted - they will jump to magnet. This very strong magnetic fraction will be composed by pure magnetite. After its elimination, your sand become light. But some black grains will not jump to magnet - they are "chromite".

After elimination of very strong magnetic fraction you should to wash your sand additionally, upto it again become black (enriched with chromite). On this stage single grains of gold can to become visible. If you'll continue to wash this black sand up to elimination of most part chromite you'll obtain extraheavy concentrate composed mainly by gold and PGM (as on my previous photo). After its drying you may to try to divide it by magnets with direct their contact with sand.

Couple years ago I bought on eBay (quite expensive) dozen metallic grains labeled as "Native Palladium, Choko river, Colombia". All 12 were magnetic in the same grade (low magnetic, only with very strong magnet). I analyzed 3 of them and all turned out Isoferroplatinum.

Native palladium (which was first discovered from this region) is much more interesting for collectors than usual ferroplatinum from here.

If I may to advise you, you should to make agreement with local gold-washers (at least with the most sane of them) to clean up their gold sand. You can extract from it all magnetic fraction on their eye and return them cleaned gold. But this magnetic fraction will be enriched with all ferroplatinum minerals. If you will reach trust from them, probably they will let you to clean their gold sand under microscope. When you pick out from gold concentrate all white metallic grains, you'll obtain good collection of PGM including OsIrRu alloys and probably Palladium (and other non native PGM - sperryllite, irarsite, osarsite etc.)

22nd May 2016 23:30 UTCHERNAN VILLEGAS

Mr Pavel: gladly can send no cost to you a sample of the magnetic concentrate for analyzes and personal collection, this concentrate is in particles of 1 mm, on the other hand have made this concentrate in concentrated nitric acid for several days and not lose weight , also in hydrochloric acid does not lose weight, this makes me think that no metal base, an opinion on the yellow precipitate, and knows some verification tests ?.

I very much like to have your advice, platinum chemistry is complex and comprehensive, this advice has a cost for me?

You mention buying native palladium, did not know of its existence will dig a little, told the Choco is a great jungle province, not a river, the main river is the San Juan, but in this province or department there are hundreds of rivers .

I attach another photo of the concentrate

thanks for your quick response

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