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| What is this metal? |
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| T3sl4co1l:
Calcium oxidizes slowly in air. Magnesium? Neither is very heavy nor hard. Suspecting something top-left transition metals, especially scandium, titanium, chromium, manganese, yttrium, zirconium. And of those, titanium should give a pink to purple Ti(3+) solution in sulfuric, chromium blue or green I think (but colored in any case), zirconium probably doesn't react at all, and scandium is very rare indeed. Manganese I think tarnishes more in air, but if not, may be a good candidate; it has a very pale pink color in solution, so it could be easy to mistake. Zinc, aluminum and other right-side transition and common metals aren't hard enough. Unless it's something really oddball like tellurium, which is also colorless in solution; but that's still not very hard, AFAIK. We can certainly rule out iron, nickel and PGMs, which aren't colorless in solution, and besides iron, dissolve very slowly if at all in acid. Once that metal stops bubbling much, if you can filter and neutralize it to get some hydroxide or carbonate (preferably use dilute NaOH, but baking soda will do), that may be informative. Also if the hydroxide dissolves in NaOH (amphoteric), or changes color over time (oxidation -- for example Mn(OH)2 is very pale, but quickly oxidizes to the brown Mn2O3). As for intermetallics, who knows; many of them are hard, but I don't know of any that are commonly made in a crystalline form like that. Large crystals implies purity, and master alloys (often mixtures of intermetallics) don't need to be that pure. Oh yeah and speaking of grinders, if it's so hard, it's probably going to be really hot when struck by a nice fast grinding wheel -- if it makes a bright shower of white sparks it's probably something like Ti or Zr, if dull red sparks it's probably something relatively inert, and if nothing at all it's probably not as hard as it seems. (Failing a proper metallurgical hardness tester, you could do the good old Mohs test using assorted items around the house.) Tim |
| Refrigerator:
--- Quote from: T3sl4co1l on May 05, 2021, 05:10:13 pm ---Calcium oxidizes slowly in air. Magnesium? Neither is very heavy nor hard. Suspecting something top-left transition metals, especially scandium, titanium, chromium, manganese, yttrium, zirconium. And of those, titanium should give a pink to purple Ti(3+) solution in sulfuric, chromium blue or green I think (but colored in any case), zirconium probably doesn't react at all, and scandium is very rare indeed. Manganese I think tarnishes more in air, but if not, may be a good candidate; it has a very pale pink color in solution, so it could be easy to mistake. Zinc, aluminum and other right-side transition and common metals aren't hard enough. Unless it's something really oddball like tellurium, which is also colorless in solution; but that's still not very hard, AFAIK. We can certainly rule out iron, nickel and PGMs, which aren't colorless in solution, and besides iron, dissolve very slowly if at all in acid. Once that metal stops bubbling much, if you can filter and neutralize it to get some hydroxide or carbonate (preferably use dilute NaOH, but baking soda will do), that may be informative. Also if the hydroxide dissolves in NaOH (amphoteric), or changes color over time (oxidation -- for example Mn(OH)2 is very pale, but quickly oxidizes to the brown Mn2O3). As for intermetallics, who knows; many of them are hard, but I don't know of any that are commonly made in a crystalline form like that. Large crystals implies purity, and master alloys (often mixtures of intermetallics) don't need to be that pure. Oh yeah and speaking of grinders, if it's so hard, it's probably going to be really hot when struck by a nice fast grinding wheel -- if it makes a bright shower of white sparks it's probably something like Ti or Zr, if dull red sparks it's probably something relatively inert, and if nothing at all it's probably not as hard as it seems. (Failing a proper metallurgical hardness tester, you could do the good old Mohs test using assorted items around the house.) Tim --- End quote --- I hit it with the angle grinder and there were absolutely no sparks that i could see. Also it might not be as hard as i made it seems but when you're going at it with a pair of snippers it does appear harder than say lead or tin. For the acid test i did manage to get some good purchase on one corner and peel some metal off. Yes i said peel, the crystals delaminated and peeled off the main chunk it's so weird. It's not titanium for sure since titanium creates bright white sparks, and it's not magnesium that much i can tell because i have some pure magnesium ingots and they don't weigh nearly as much as this chunk does. I wonder can i just pour some of the acid solution into some ethanol and watch the color as it burns? |
| tszaboo:
I think it is pyrite. I also found a chunk when I was a kid, though the metal content was much less. |
| Benta:
My guess would be cobalt. |
| Refrigerator:
Some news! Went to try the ethanol experiment but before that i noticed the acid solution was a little thicker than expected. Actually it was not thick, turns out some clear white crystals precipitated out of solution. It's some kind of sulfate/ite right? Next i'll try pouring the acid off and mixing some ethanol into the crystals, maybe i can get some colour when it burns |
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