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Thread: Help with identification....

  1. #1 Help with identification.... 
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    HI there, I found this "rock" about 25 years ago in Southern Minnesota... I have not been able to find out what it is... can anyone assist? It is very shiny, almost Chrome looking and extremely heavy.

    Thanks

    Chuckphoto (2).JPG


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    Looks like blue pyrite...


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    WYSIWYG Moderator marnixR's Avatar
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    looks like azurite to me
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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    Universal Mind John Galt's Avatar
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    It's years, or decades since I've done any mineralogy, but this evoked the response stibnite. If you draw it across a ceramic material it should leave a streak. Does it do so?
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    Quote Originally Posted by John Galt View Post
    If you draw it across a ceramic material it should leave a streak. Does it do so?
    This post allows a method of testing- excellent.
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    Universal Mind John Galt's Avatar
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    Quote Originally Posted by John Galt View Post
    It's years, or decades since I've done any mineralogy, but this evoked the response stibnite. If you draw it across a ceramic material it should leave a streak. Does it do so?
    It should also, if memory serves, feel greasy to the touch. Both are reflections of its very low hardness - only 2 or 3 on Moh's scale.
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    Northern Horse Whisperer Moderator scheherazade's Avatar
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    Quote Originally Posted by mnflyfisher View Post
    HI there, I found this "rock" about 25 years ago in Southern Minnesota... I have not been able to find out what it is... can anyone assist? It is very shiny, almost Chrome looking and extremely heavy.

    Thanks

    Chuckphoto (2).JPG
    This link goes to a mineral table that might prove useful for your purposes. There are images of the minerals when you go to the home page of each.

    Mineral Identification Key - Table IB
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  9. #8  
    Forum Radioactive Isotope Paleoichneum's Avatar
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    Its a large chuck of massive galena. The cleavage planes and metallic coloring are distinct.
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

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    WYSIWYG Moderator marnixR's Avatar
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    does galena show such a blue colour ? i would have thought it was more greyish metallic
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    Quote Originally Posted by Paleoichneum View Post
    The cleavage ...
    You said cleavage.
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  12. #11  
    Forum Radioactive Isotope Paleoichneum's Avatar
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    Quote Originally Posted by marnixR View Post
    does galena show such a blue colour ? i would have thought it was more greyish metallic
    It's dependent of the amount of oxidation on the surface, and also the quality and type of light that is reflecting off the cleavage faces from the window in the background. Also note that the crystal structure is clearly cubic (isometric) so azurite and stibnite are eliminated. Whereas the clearly silver-blue metallic coloration and distinct cleavage planes of the crystal eliminates pyrite as an option.
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

    The needs of the many outweigh the need of the few - Spock of Vulcan & Sentinel Prime of Cybertron ---proof that "the needs" are in the eye of the beholder.
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  13. #12  
    Forum Radioactive Isotope Paleoichneum's Avatar
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    0095554001350221181.jpg

    note the isometric faces and blueish tinge dues to minute oxidation to smithsonite/hemimorphite on the faces. (Specimen can be viewed here http://www.mindat.org/photo-492604.html
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

    The needs of the many outweigh the need of the few - Spock of Vulcan & Sentinel Prime of Cybertron ---proof that "the needs" are in the eye of the beholder.
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    WYSIWYG Moderator marnixR's Avatar
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    fair enough, i relent in the face of your expertise - azurite was a mere layman's (and only slightly educated) guess, and i'm quite willing to amdit that i could be wrong
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  15. #14  
    Forum Radioactive Isotope Paleoichneum's Avatar
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    its all good
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

    The needs of the many outweigh the need of the few - Spock of Vulcan & Sentinel Prime of Cybertron ---proof that "the needs" are in the eye of the beholder.
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  16. #15  
    Life-Size Nanoputian Flick Montana's Avatar
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    I'd say galena. You say it is highly metallic and dense, so if it breaks into cubes when crushed, it's most likely galena.

    That's a nice big sample, too. Good find.
    "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us." -Calvin
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