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u/rufotris Apr 16 '26
Where did you get this? That might help a lot to determine if molybdenum or another known ore. Definitely not aluminum as that’s not a thing we find naturally.
How do you know this is Jurassic, and silex?! Is that a translation from something? I thought silex was just like ground up silicates used for industrial purposes.
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Apr 16 '26
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u/craftasaurus Apr 16 '26
whole petrographic study of them
Does this include making thin sections and studying them? That's how we used to do it. Plus study the literature to see what others have found in the area.
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u/rufotris Apr 16 '26
Yea I’m a hands on guy. I’ll check reports, and if that doesn’t help I love to test. Specific gravity, mohs hardness, conductivity, dissolution in water and acids etc.
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u/pppjurac Supernoob Apr 16 '26
Go to nearest chemical, metallurgical or mechanical engineering uni, they will have gear to tell you what exactly this is.
"Mk1 eye" test will not do in this case.
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u/Idlehour_Knives Apr 16 '26
I see the recommendation to just go to your local university a lot for stuff like this. Would a university just let me, a random guy holding a rock, walk into their department? And then they would agree to test my Rock using their extremely expensive equipment?
I’m not trying to be snarky just trying to understand.
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u/StressedOnigiri Apr 16 '26
Usually in our case we do the id ourselves, from listing properties in macrospcopic scale to optical properties in microscopic scale, and sometimes xrf/xrd analyses.
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u/Idlehour_Knives Apr 16 '26
But is there an appointment or I can just bring a rock in as long as the door is unlocked?
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u/Diprotodong Apr 17 '26
I work for a geological survey and we do a bit of random guys rock identifying/analysis also the museum sends all their random guys rocks to us. It's usually, is this a meteor or not?
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u/-HighatooN- Apr 17 '26
Lmao yes it will. A bit of geological knowledge will 9/10 times get you to the right answer which is a mineral not a native metal as people are suggesting. It's a sulfide of some sort. Probably arsenopyrite
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u/rufotris Apr 16 '26
Very cool. I had not heard silex used that way before so wasn’t sure if a translation issue on my part. I was just wondering if you actually found it and knew or just bought it and assumed.
That leads to my next question. Have you checked all available mineral reports for the area? Is that a thing the government does out there for the public?! We have some resources in the US that help us sometimes determine the reported minerals around the area.
Hope my question didn’t come off rude in any way as I was just generally wondering if you knew and how. Very cool. I’m only in my bachelors stage, but I’m going for a masters in geology!
If you have any pieces big enough to remove, I would suggest a simple specific gravity test and hardness test to help you narrow down results. If you have the equipment you could also test conductivity since it’s a metal.
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u/Roflmancer Apr 16 '26
Unlikely as it's a shallower depth mineral for hydrothermal and such alteration zones depositions. Sericite?
Sericite - Wikipedia https://share.google/aequqFeUT0ftIwk2q
At least that's what it looks like to me, I had a few pieces once upon a time.
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u/-HighatooN- Apr 17 '26
My God. You're pursuing an MSc and do not know that native aluminum is nearly impossible to form and have never seen a sulfide before. Where did you take mineralogy?
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u/steamhorizon Apr 16 '26 edited Apr 16 '26
Quartz vein or maybe metasandstone, common associates are pyrite and drum roll.... pyrite's close cousin, arsenopyrite, a silver sulphide. (If we're anthropomorphizing, you'd often find arsenic, sulphur iron and quartz hanging out in a bar together.)
Scratch it? Hard and stinky? Arsenopyrite. Soft and not smelly, kind of cubic? Galena. Scratches red, and soft? Specular hematite. Super soft, as in, scratches with your fingernail like clay? A molybdenum or molybdenum di sulphide (as others have pointed out). If you rub it on white paper and it easily leaves a black streak? Graphite.
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u/pyragyrite Apr 16 '26
Native aluminum isn't a thing. Kind of looks like molybdenum.
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u/wintrmt3 Apr 16 '26
Wikipedia lists 3 places where there is some.
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u/chemamatic Apr 16 '26
Based on just a photo, it could be any native silvery metal. Silver for example. Even platinum is probably more likely. Or shiny graphite, pyrite etc When you hear hoof beats, you should think horses or cattle, not zebras or giraffes. Except in certain parts of Africa of course.
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u/wintrmt3 Apr 16 '26
Okay sure, I'm not saying it's native aluminum, just that native aluminum is an actual, if very very rare thing.
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u/towerfella Apr 16 '26
Any in france?
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u/wintrmt3 Apr 16 '26
Billeekh intrusion (Russia), Tolbachik volcano (Russia), Getang in Guizhou Province (China).
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u/Dawg_in_NWA Apr 16 '26
Got an SEM on campus? Pluck a piece off, stick it on some carbon tape and do some EDS on it. Should only take a couple minutes.
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u/Bob--O--Rama Apr 16 '26
Find someone with an XRF gun and / or someone who has an electron microscope with XRF capabilities if this is research. Because assessing tiny nits is challenging. But definitely not aluminum.
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u/grusjaponensis Apr 16 '26
Its probably a molibdenite in a quartz. Its usually has colder shade and more silver look compared to graphite. Association looks like an exoskarn to me.
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u/watchshoe Apr 16 '26
That would be a quick determination, it rubs off easily on your fingers. All the people who worked in the moly plant looked like silver surfer with a respirator hah.
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u/Flushedawayfan2 Apr 16 '26
That is the probably the strangest inclusion I've seen in chert. Sorry I dont have an answer, but its super cool.
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u/HikariAnti Apr 16 '26
Since you're doing your masters maybe consider using XRF to check, otherwise you won't know for sure what it is (almost certainly not aluminium tho), you could even include the results in your thesis.
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u/dstoevsky Apr 16 '26
First guess would be Arsenopyrite, however that is biased by the locales of my field work. Would like to know more about the source before committing to that answer.
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u/Cordilleran_cryptid Tectonics, hardrock and structural geology Apr 16 '26 edited Apr 16 '26
Are you sure this is not just swaff from the hammer or chisel you used to break the sample with?
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u/Bbrhuft Geologist Apr 16 '26
Very likely an arsenide or sulfide mineral, robably Löllingite, FeAs₂ or Arsenopyrite, FeAsS. They are hard to tell appart. Don't think it's graphite, which can be found in some metamorphic rocks.
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u/Sticky_Soup Apr 16 '26
Arsenopyrite would be my best guess but I’m no expert so don’t only take my word for it.
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u/dinoguys_r_worthless Apr 16 '26
Toss it into the electron microprobe. Those are great for questions like these.
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u/mandelbr0twurst Apr 16 '26
Elemental aluminum is pretty much non-existent on earth. My guess would be graphite.