Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: hvs on 13/07/2014 13:35:35

Title: Another rock id please..
Post by: hvs on 13/07/2014 13:35:35

Hello, Im from upstate NY and collect native American indian stone tools.. I found these 2 stones last year on a old indian campsite and need help identifying them.. Stones are very heavy for there size and have a brownish crust around them thats flaking off in many areas. A magnet is attracted to the stones. Chondrules are present and under a mgnifying glass are black and smooth almost gem shaped..30 years of picking up stones ive never seen anything like these and hoping for some help.. Thanks Ron

 

 (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi764.photobucket.com%2Falbums%2Fxx288%2Fcenterpining%2F20140712_170400.jpeg&hash=aca13674b81577483072109aa6a39a16)

  (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi764.photobucket.com%2Falbums%2Fxx288%2Fcenterpining%2F20140712_170416.jpeg&hash=4bf5f16026acc734247726113c44b836)

 (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi764.photobucket.com%2Falbums%2Fxx288%2Fcenterpining%2F20140712_170330.jpeg&hash=deefb4279bb5485ee790bb7274f6efab)

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Title: Re: Another rock id please..
Post by: hvs on 13/07/2014 19:05:47

Anybody??

Title: Re: Another rock id please..
Post by: RD on 13/07/2014 23:19:05

Possibly a combination like galena on pyrite ? ...
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.curriehj.freeserve.co.uk%2Fgalire1.jpg&hash=a134d7f4e2143d27ea48dd8a4181ec04)
http://www.curriehj.freeserve.co.uk/republic.htm

Just a guess , you may be better off trying a forum dedicated to minerals
like mindat.org ... http://www.mindat.org/forum.php

Title: Re: Another rock id please..
Post by: hvs on 14/07/2014 11:21:47

Thanks RD i think u might be right ill check out that other forum.. Thanks again. Ron

Title: Re: Another rock id please..
Post by: hvs on 15/07/2014 01:56:33

Ok i washed one and cleaned it with a soft toothbrush and the brown crust seemed to be dirt and most of it came off. Since i have 2 i cut one in half [:(]..No clear crystals just black. The smaller stone weighs 139.5 grams larger one is 157 grams..

  (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi764.photobucket.com%2Falbums%2Fxx288%2Fcenterpining%2Fr3.jpg&hash=633a1830125f2fb5565c490ad40836ee)

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Title: Re: Another rock id please..
Post by: RD on 15/07/2014 10:03:10

Iron-ore is a colour-match ...

Quote

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The dark layers in this boulder are mainly composed of magnetite (Fe3O4) while the red layers are chalcedony, a form of silica (SiO2) that is colored red by tiny iron oxide particles.

http://www.amnh.org/exhibitions/permanent-exhibitions/... /banded-iron-formation (http://www.amnh.org/exhibitions/permanent-exhibitions/rose-center-for-earth-and-space/david-s.-and-ruth-l.-gottesman-hall-of-planet-earth/how-has-the-earth-evolved/banded-iron-formation)

Title: Re: Another rock id please..
Post by: hvs on 15/07/2014 17:36:35

Very interesting RD, Thanks.. Take a look at what others think on another forum i posted on..
http://www.mindat.org/mesg-11-329033.html

Title: Re: Another rock id please..
Post by: RD on 15/07/2014 21:03:14

Quote from: hvs on 15/07/2014 17:36:35

Very interesting RD, Thanks.. Take a look at what others think on another forum i posted on..
http://www.mindat.org/mesg-11-329033.html

Pic r2 (http://i764.photobucket.com/albums/xx288/centerpining/r2.jpg) does look like it has glacial striation (http://en.wikipedia.org/wiki/Glacial_striation), (parallel grooves), on the flat surface.
I don't think the wear would look like that if it was an artifact ground-down for pigment.

Title: Re: Another rock id please..
Post by: hvs on 16/07/2014 16:40:21

Polished it up a bit and it sure looks like copper inside..
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi764.photobucket.com%2Falbums%2Fxx288%2Fcenterpining%2Fn2.jpg&hash=c209a42d02b9f1e3f6311a402a66b0f9)

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi764.photobucket.com%2Falbums%2Fxx288%2Fcenterpining%2Fn1.jpg&hash=09b0459a2bf3fcbcc1635af71acbdd30)

Title: Re: Another rock id please..
Post by: Bass on 16/07/2014 17:43:53

Have you checked this with a magnet?  What about hardness?
Native copper is ductile and malleable- so if you try to scratch it with a knife or sharp point, it should leave a groove with little to no material coming off the specimen.

Title: Re: Another rock id please..
Post by: hvs on 16/07/2014 21:03:52

Its very hard like steel. The copper seems very hard just like the material around it but it does scratch . i figured the copper would be soft but its not as soft as one would think.. When i hang a small magnet on a string it does stick to the stone.. "Just lightly pulls to the stone."

Title: Re: Another rock id please..
Post by: Bass on 18/07/2014 00:51:45

given the similar hardness and the magnetism, my guess would be magnetite weathering to hematite.