PPDs actively accrete onto their host protostars. Recently, PPDs have been found to have rich substructures ( 5, 6), which may suggest that they form planets extremely efficiently. About half of all PPDs disperse between ~2 and 4 million years (Ma) after collapse of their parent molecular clouds ( 3, 4). The hundreds of PPDs currently accessible to astronomical observations have typical radii of 10 1 to 10 2 astronomical units (AU) and masses ranging from 10 −4 to 10 −1 (median, ~10 −2) solar masses ( M ⨀) ( 2). They consist mostly of hydrogen and helium gas, with about ~1% by mass solids (i.e., dust) that serve as the building blocks for planetary bodies. PPDs form as consequence of the collapse of molecular cloud cores under angular momentum conservation and are a critical intermediate stage of solar system formation ( 2). Most, but not all, of the fraudulent material comes from China, the location of the Nantan fall, and disreputable sellers seeking to capitalize on that fact are far too common.Newly formed Sun-like stars are surrounded by planar distributions of circumstellar material known as protoplanetary disks (PPDs) ( 1). I do prefer the nitol method though, any material containing chlorine, including tap water, should be strictly avoided with any meteorite containing iron.Īs for the NWA X, I don't know. It was used in the fabrication of printed circuit boards, so it's not hard to find. An alternative is to dissolve some ferric chloride in water to produce an etchant. The nitric acid in somewhat diluted form is available on eBay for example, it's often used in gold testing. This is only a test to determine the presence or absence of the Widmanstatten pattern, for a permanent etched specimen a few more details are needed. If there's a pattern there, it will take only a couple of minutes to appear. Brush the resulting nitol onto the surface, or immerse the specimen in the solution. Always add the acid to the alcohol, not the reverse. If starting with concentrated nitric acid, dilute it in alcohol to 1:16 (mostly alcohol). Semi-polish the surface up to at least 320 grit, 400 - 600 would be better. It need not be perfectly free of crust, just mostly 'fresh' metal. The etching process isn't difficult, some care needs to be taken when handling the nitric acid, of course. All iron meteorites contain at least some nickel. There is a chemical test given in Rocks From Space, by O Richard Norton, that will confirm even trace amounts of nickel, but it's fairly involved and involves chemicals not readily available locally. I'm not familiar with the nickel tests you mention. I think your assessment of folded lines in possible slag is much closer to the mark. To create the odd pattern in the pics would imply the specimen tumbling in different orientations, which would decrease the heating effect and likely not result in coherent lines. Yes, the lines are reminiscent of what are known as flow lines, which can appear when a meteor remains in one position sufficiently long for the surface to melt and begin to flow from the leading surface. What would be a good chemical test for Nickel? Nickel Alert or Nickel Guard? If no nickel is found with a chemical test, would that definitively indicate terrestrial origin? The changing directions - they wouldn't be lines from flow melt of a rock spinning or changing orientation through the atmosphere? I too was wondering about those lines - I'm starting to think this stone a folded piece of slag as some of lines appear wavy. Attraction to a magnet is not at all a reliable indicator, many terrestrial rocks are magnetic.Įdited by lee14, 03 March 2020 - 10:39 AM. Most, but not all, iron meteorites will display such a pattern. Then, attempting to etch the surface with nitol (a solution of nitric acid in alcohol), or ferric chloride in a water solution, would produce a characteristic Widmanstatten pattern if it was in reality a meteorite. A far easier alternative to cutting would be to choose the flattest 'side' and use a bench type belt sander to grind a flat 'window' and expose the interior. Cutting one in half is not a trivial task, and is not something readily done with say, a hacksaw. The presence of nickel, along with trace amounts of other elements, can be a reliable indicator, and can also be determined by chemical tests. Or, you could have an XRF (X-Ray fluorescence) test done, which will reveal the metallic content and their relative amounts. Lab testing would quite possibly exceed the value of a specimen this size. While some of the surfaces look right, the fine lines running in different directions, do not. Rocks alleged to be found in the California desert are more likely to be of terrestrial origin than meteorites.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |