From: '''newspam'''@nonad.co.uk   
      
   On 31/12/2025 11:32, Jeroen Belleman wrote:   
   > On 12/31/25 12:01, Martin Brown wrote:   
   >> On 29/12/2025 16:04, john larkin wrote:   
   >>>   
   >>> Oh, I've worked with TOF atom probe spectroscopy and backscatter   
   >>> analysis and analytical NMR and all sorts of exotic physics.   
   >>> Physiscists need help with circuits.   
   >>>   
   >>> But a lot of the solar system has rocks with similar isotopic content.   
   >>> Declaring a meteorite to be a chunk knocked of Mars is a real   
   >>> hand-waver.   
   >>   
   >> Not really. The oxygen isotopic signature on Mars is different enough   
   >> to recognise Mars rocks. Although that doesn't stop charlatans on eBay   
   >> selling Mars meteorites that are just similar looking Earth rocks.   
   >>   
   >> Anyone with a stable isotope MS or a noble gas MS would be able to   
   >> test the gasses in inclusions and see old Martian atmosphere if it is   
   >> real.   
   >   
   > I suppose analysis methods are more refined these days, but in 1974 I   
   > simulated a meteorite hit in a class mate's garden as a hoax. What I   
   > did not anticipate is that everyone took this seriously. It was just a   
   > piece of steel furnace slag, but even the Max Planck institute in   
   > Germany refused to admit they'd been fooled.   
      
   Back then they wouldn't have any easy way of testing it. That all   
   changed in about 1990 when TOF ion probes and laser ablation mass   
   spectrometry came of age. Before that you had to pound it to dust and   
   dissolve in HF (not nice) then do some very fancy wet chemistry.   
      
   I worked on software for the mass spectrometric rare earth element   
   analysis of meteorites at one time (and on dating ancient rocks).   
      
   The geologists get very excited about the Europium anomaly in them. That   
   one species is a marker that varies enormously with the type of rock and   
   the chemical environment when and where it was formed.   
      
   https://en.wikipedia.org/wiki/Europium_anomaly   
      
   I understand that it occurs when Europium is in an unusual oxidation   
   state and is commonly seen in stony chondrites and moon rocks. I have   
   seen a few close up in a glove box. I never had the chance to smell any.   
   Keeping them clean under an inert dry atmosphere was a priority.   
      
   Cute demo with a modern Nd magnet you can collect micrometeorites from   
   the black gunge that accumulates in PVC gutters. Too small for the naked   
   eye to see but obvious with even a basic toy microscope.   
      
   https://www.quekett.org/resources/article-archive/bsw-2017/bsw17   
   micrometeorites   
      
   Some nice almost safe for modern H&S rules science demos on that site.   
      
   --   
   Martin Brown   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)