Talk:Osmium/GA1

GA Review
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This article deserves GA status. It is well written, neutral, stable and well referenced with in-line citations (thus verifiable). The topic is clearly of top importance. There were minor problems with style, references and a few statements, and some facts had to be added. All that was fixed in the review process. Other editors are encouraged to further improve this article. Some of the old comments comments are listed below. Materialscientist (talk) 09:36, 18 June 2009 (UTC)

1) Images are lacking. Suggestions: (i) Find a way to crop either File:Osmium 1.jpg or File:Osmium.jpg and put a cropped one into the elementbox. (ii) Remove File:Platinum nuggets.jpg as poorly related to this article. (iii) Find interesting images. For example, electron micrograph demonstrating advantage of Os staining (unfortunately, I haven't got my pictures on that). Materialscientist (talk) 09:55, 12 June 2009 (UTC)
 * wikicommons images on stained tem images might contain a image stained with Os, but i do not have a clue.--Stone (talk) 15:03, 12 June 2009 (UTC)
 * A colleague gave me a nice image on staining (which I put there), but this only partially solves the above image problem. Materialscientist (talk) 12:08, 13 June 2009 (UTC)
 * I think the Platinum nuggets are a good image for the article for the occurence section. Platinum placer deposits are the best place to find osmium iridium and most platinum nuggets contain osmium and iridium in a small amount.--Stone (talk) 11:37, 15 June 2009 (UTC)
 * Added another image of osmium.--Stone (talk) 20:58, 15 June 2009 (UTC)

2) "Osmium forms compounds with the oxidation states ranging from 0 to +8" conflicts with the elementbox values. Materialscientist (talk) 09:55, 12 June 2009 (UTC)
 * Have a look in Max Schmidt an Holemann.--Stone (talk) 15:03, 12 June 2009 (UTC)
 * DONE have ref for -2 and -1 and added it to the article.--Stone (talk) 11:37, 15 June 2009 (UTC)

3) Numbers 22562 ± 0.009 and 22587 ± 0.009 look wrong, and I would suggest converting into g/cm3.Materialscientist (talk) 09:55, 12 June 2009 (UTC)
 * good suggestion!--Stone (talk) 15:03, 12 June 2009 (UTC)
 * I already fixed that. Materialscientist (talk) 05:23, 18 June 2009 (UTC)

4) I didn't notice a reference for staining. Materialscientist (talk) 09:55, 12 June 2009 (UTC)
 * added ref for the staining.--Stone (talk) 15:03, 12 June 2009 (UTC)

5) Osmium easily oxidizes that should give it a tint. For example, is blue tint due to oxidation ? If so, please put it into the article.Materialscientist (talk) 09:55, 12 June 2009 (UTC)
 * The oxidation productis OsO4 from the ref, so I do not think this will cause the blue tint.-Stone (talk) 15:03, 12 June 2009 (UTC)

6) Numbers are needed on crust abundance, and preferably on distribution (meaning what is the major form, osmium-rich alloys like OsIr or osmium-poor, and which ones. I think the article only talks about major deposits, not major compounds). Materialscientist (talk) 12:08, 13 June 2009 (UTC)

Large deposits of the first type are found in south africa, while the second type is the main source for PGMs in Russia and Canada. After leaching of the copper nickel ores with sulfuric acid at elevated temperatures and elevated pressure under oxygen the residuals contain most of the PGMs which can be extracted with chlorine and hydrochlric acid. The dissolved PGMs are extracted by ion exchange extraction. The polymeric ion exchange resin can be burned and the residual ash contains most of the PGMs, which are separated from each other by clasical methods or chromatography. The two PGMs Osmium and Iridium are the compounds with the lowest concentration in the leaching residues. For example the concentrate 2 has a content of 450g/t of platinum while the concentration of Iridium is 37g/t and of osmium 26g/t.
 * Added abundance for the continetal crust. 0.05ppb. This number is from 1995 and a good estimation, but most of the other numbers given in the Abundances of the elements (data page) are different and vary by two orders of magnitude. The numbers are not much better for iridium. so I took the newest and looked for others which are in the same order of magnitude.--Stone (talk) 07:25, 18 June 2009 (UTC)

7) Please search (I will too) applications of osmium coatings. I think they were used to increase UV reflection, but abandoned because of oxidation. Materialscientist (talk) 12:15, 13 June 2009 (UTC)
 * At 600A osmium has a reflectivity two times that of gold. UV spectrometers with osmium coated mirrors where flown in several missions also onboard the space shuttle, but it became clear that the atomic oxygen in low earth orbit is abundat enough to significantly deteriorate the osmium layer.
 * Added a few sentences on the topic with the refs.--Stone (talk) 20:47, 15 June 2009 (UTC)

A comment on the oxidation states. According to list of oxidation states of the elements, osmium can have not only all oxidation states from 0 to +8, but also oxidation state −2. --Itub (talk) 12:56, 12 June 2009 (UTC)
 * I don't really believe those lists because I found already several errors in other properties. Materialscientist (talk) 12:08, 13 June 2009 (UTC)
 * I believe in that list because I wrote it myself based on what I consider a reliable source and have double-checked every addition made by others. If you think there is an error, please let me know. --Itub (talk) 12:40, 13 June 2009 (UTC)
 * I respect that, but I have not found reliable evidence for Os 2- and 1- compounds yet. There is a mentioning that they correspond to osmium hydrogencarbonyls, but those are hard to find too. I'm am awaiting a comment from Stone on that. This might answer your question. I don't have access to the book you used in the list of oxidation states of the elements. If you could provide the primary source for Os 2-, this would be very much appreciated. Materialscientist (talk) 23:48, 13 June 2009 (UTC)
 * This is done and for both oxydation sates there is a ref.--Stone (talk) 11:37, 15 June 2009 (UTC)