What is this thing? (Rock edition)
March 20, 2018 11:49 AM
I have an interesting rock/artifact/thing that I found in a creek in a state park in upstate New York in the early 1980s. What is it?
I found this in a shallow creek in upstate New York on a school field trip in second grade, and I just found it again while moving. I really want to know a) what kind of stone it is and b) what its function is/was meant to be. Any guesses more informed than mine? Some details (I am not a geologist or an archaeologist, so excuse the non technical terms):
- it's a little less than three inches long and about an inch wide.
- it was clearly shaped and polished on purpose by humans at some point and was probably then eroded by water?
- it has a silvery gray surface that reflects light a little bit and has very tiny sparkly bits evenly distributed throughout.
- it has notable diagonal scratches on the surface in one side.
- I scratched the surface with a both a metal thumbtack and my fingernail, and the scratch showed in both cases.
Any idea what this is made of and/or what it might have been used for when? It's plausible that it's very old, but not necessarily.
I found this in a shallow creek in upstate New York on a school field trip in second grade, and I just found it again while moving. I really want to know a) what kind of stone it is and b) what its function is/was meant to be. Any guesses more informed than mine? Some details (I am not a geologist or an archaeologist, so excuse the non technical terms):
- it's a little less than three inches long and about an inch wide.
- it was clearly shaped and polished on purpose by humans at some point and was probably then eroded by water?
- it has a silvery gray surface that reflects light a little bit and has very tiny sparkly bits evenly distributed throughout.
- it has notable diagonal scratches on the surface in one side.
- I scratched the surface with a both a metal thumbtack and my fingernail, and the scratch showed in both cases.
Any idea what this is made of and/or what it might have been used for when? It's plausible that it's very old, but not necessarily.
Take better pics with a penny for size reference and email your inquiry here: info@NHM.org
You could send the same request to the Natural History Museum in New York, too. Just call them and ask for a contact email. You're not imposing, this is what they do!
posted by jbenben at 12:38 PM on March 20, 2018
You could send the same request to the Natural History Museum in New York, too. Just call them and ask for a contact email. You're not imposing, this is what they do!
posted by jbenben at 12:38 PM on March 20, 2018
If it can be scratched by a fingernail and metal, it's a very soft rock, too soft to be a sharpening stone. I am a geologist, but I am not a knife expert. The only sharpening stone I have has diamond grit embedded in it- you need something harder than metal to sharpen, I would think?
Based on this geologic map (you can zoom in on New York and click on colors to see what they represent) I'm seeing a lot of meta-sedimentary rocks rocks in the North. Just based on your description and the fact that it's been shaped my first guess is soapstone. Soapstone is primarily made up of talc, and seeing that there's a town in New York called Talcville... well, I think that's a reasonable guess.
Other rocks soft enough to be scratched by a fingernail (which is 2.5 on Mohs hardness scale) that might be in the area (based on looking at some rockhounding sites) are:
Graphite (less than 1)
Maybe some crumbly marble (3-4)- metal would scratch, probably not a fingernail
Serpentinite (2 or 3-6)
Halite (2-2.5)
posted by Secretariat at 12:49 PM on March 20, 2018
Based on this geologic map (you can zoom in on New York and click on colors to see what they represent) I'm seeing a lot of meta-sedimentary rocks rocks in the North. Just based on your description and the fact that it's been shaped my first guess is soapstone. Soapstone is primarily made up of talc, and seeing that there's a town in New York called Talcville... well, I think that's a reasonable guess.
Other rocks soft enough to be scratched by a fingernail (which is 2.5 on Mohs hardness scale) that might be in the area (based on looking at some rockhounding sites) are:
Graphite (less than 1)
Maybe some crumbly marble (3-4)- metal would scratch, probably not a fingernail
Serpentinite (2 or 3-6)
Halite (2-2.5)
posted by Secretariat at 12:49 PM on March 20, 2018
For upstate New York, the first museum I would try to contact would be the New York State Museum, which is in Albany. You will probably want to inquire via the Research and Collections contact info - they have several curators of geology.
posted by pemberkins at 1:04 PM on March 20, 2018
posted by pemberkins at 1:04 PM on March 20, 2018
For the question of its age, who shaped it and why, I think you should talk to an archaeologist, rather than a geologist. Most archaeologists are going to be able to identify the materials stone tools or art pieces that they study are made out of, but few geologists know much about human-shaped stones.
I guess to follow up on my other suggested rocks:
If it's graphite, you can write with it. It's probably also all over your hands.
If it's halite, it tastes salty when you lick it.
If it's marble, it will fizz if you drop dilute hydrochloric acid on it (but I suppose you don't have this at home?)
posted by Secretariat at 2:10 PM on March 20, 2018
I guess to follow up on my other suggested rocks:
If it's graphite, you can write with it. It's probably also all over your hands.
If it's halite, it tastes salty when you lick it.
If it's marble, it will fizz if you drop dilute hydrochloric acid on it (but I suppose you don't have this at home?)
posted by Secretariat at 2:10 PM on March 20, 2018
Marble will also fizz (slowly) if you drop horticultural vinegar on it. This might only be a thing in cities with pesticide laws, though
posted by scruss at 2:17 PM on March 20, 2018
posted by scruss at 2:17 PM on March 20, 2018
For archaeology, I would still recommend contacting the New York State Museum Research & Collections group - there are also curators of history, bioarchaeology, geoarchaeology, and several other specializations. Someone there should be able to help.
posted by pemberkins at 2:33 PM on March 20, 2018
posted by pemberkins at 2:33 PM on March 20, 2018
If it's marble, it will fizz if you drop dilute hydrochloric acid on it (but I suppose you don't have this at home?)
You can get hydrochloric acid, under the name "muriatic acid", in the paint section of a typical hardware store. Should be pretty cheap.
posted by clawsoon at 3:00 PM on March 20, 2018
You can get hydrochloric acid, under the name "muriatic acid", in the paint section of a typical hardware store. Should be pretty cheap.
posted by clawsoon at 3:00 PM on March 20, 2018
Possibly a celt? (Sparkly bits, scratch-able; maybe it's schist.)
posted by Iris Gambol at 3:23 PM on March 20, 2018
posted by Iris Gambol at 3:23 PM on March 20, 2018
I don't think its necessarily shaped by humans, that is within a normal shape for alluvium. I'm pretty sure its a type of serpentinite which is super soft. The green minerals are olivine. Soapstone would feel greasy, give it a rub.
posted by cakebatter at 3:33 PM on March 20, 2018
posted by cakebatter at 3:33 PM on March 20, 2018
Silvery gray, sparkly, and can be scratched with a fingernail? It sounds very much like graphite. If you rub it on a piece of paper, does it leave a gray mark? If so, I'm voting graphite.
It terms of ancient human use, it would be unlikely. It's much too soft to be used for sharpening or grinding. With the softness described, the scratches are probably just from it traveling down the creek.
/mineralogist
posted by Gneisskate at 9:33 AM on March 21, 2018
It terms of ancient human use, it would be unlikely. It's much too soft to be used for sharpening or grinding. With the softness described, the scratches are probably just from it traveling down the creek.
/mineralogist
posted by Gneisskate at 9:33 AM on March 21, 2018
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posted by Dr Dracator at 12:13 PM on March 20, 2018