I am more curious about the metal on the surface (if it's even metal?) on this stone :)

  • I don't really remember where I found it, probably at this beach of the Baltic Sea, but there is also a chance that I found it in another place that has a natural beach.
  • It's smooth to the touch, I think the proper term would be greasy lustre, but I'm not a geologist. It has marble like colors - white, grey, black. There is a little of dark green on one side. The linings have definitely metallic lustre. They have aluminum color and on closer inspection it seems as if they are made of tiny metal crystals.
  • The hardness is about 6.5 - 7 (steel got scratched, quartz scratched it). I can't identify the linings hardness.
  • mass - 17 g, capacity - 5 ml (measurements where done without proper equipment with home tools), density 3,4 g/ml.

measured in cm rock rock rock


closed as off-topic by Jan Doggen, Semidiurnal Simon, BillDOe, arkaia, Erik Sep 17 at 7:00

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    $\begingroup$ Well my first idea was to check metals in their not refined form. The closest what I could find was to my surprise tellurium metal. Everything would be fine if it's rarity wouldn't be compared to platinum. This is an example of a tellurium ore drive.google.com/file/d/1SeABbygkHyeinekdyAUkWcPQARVGVk0o/… $\endgroup$ – Emily Jul 14 at 19:58
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    $\begingroup$ @Universal_learner We no longer accept?? Are you refering to this meta without any upvotes or answers? No one-person actions please. $\endgroup$ – Jan Doggen Jul 15 at 7:19

This looks to me to be graphite crystals in marble or quartzite. Based on your comment about the hardness I would probably go with quartzite. Highly metamophosed graphite can look metallic. Both the graphite and the calcium carbonate/quartz crystals are quite large indicating a long time spent at depth. Try to scratch the "metal" with a needle. If it is graphite it will scratch easily and produce gray dust.

If you could remember where you found it a check of rock types found nearby would probably tell us what this is.

  • $\begingroup$ Density is a bit high for quartzite (graphite couldn't increase it). But this can be related with an analytical error measuring volume. $\endgroup$ – user12525 Jul 15 at 8:16
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    $\begingroup$ I tried scratching it and it came off in a similar shape of a glitter (glittery pieces also reflect light as on surface), however it did not scratch easily and no grey dust came out. I was hesitant to post more accurate location, because I thought that I found it on a beach that is regularly refilled with sand and stones brought from abroad, meaning that the stone could have come from any other region (here are the coordinates 56.026489, 21.070276). But there is also a chance that I found it in another place that has a natural beach (57.011199, 21.383781). $\endgroup$ – Emily Jul 15 at 8:21
  • $\begingroup$ Could be molybdenite? $\endgroup$ – Gimelist Jul 15 at 22:00

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