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Thread: Mineral Identification

  1. #1 Mineral Identification 
    Forum Sophomore
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    Sep 2005
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    I will have a practical mineral test next week -- a pain! Please consider the appearance and luster of each mienral only because I can't perform any hardness, streak test in the practical test next week! Just by "looking" at it!

    Please click the following address for the image of the minerals!
    http://www.geocities.com/asdfasdf23135/DSC00586.JPG
    1) The numbers 2-gypsum, 4-fluorite, 7-quartz, 14-glass look so alike to me, is there any difference in appearance in these four things that can allow us to distinguish from one another?

    2) The numbers 3-calcite, 6-orthoclase feldspar, 15-alabaster look exactly the same to me, is there any difference in appearance in these three things that can allow us to distinguish from one another?

    Please click the following image for the second set of minerals!
    http://www.geocities.com/asdfasdf23135/DSC00595.JPG
    3) Number 15 is called a "quartz crystal", how is it different from a "quartz mineral"?

    Who has good mineral-identifying skills? I find it hard to differentiate one mineral from another! I really really need your help! Thank you!


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  3. #2 Re: Mineral Identification 
    Forum Cosmic Wizard SkinWalker's Avatar
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    Quote Originally Posted by kingwinner
    Please click the following address for the image of the minerals!
    http://www.geocities.com/asdfasdf23135/DSC00586.JPG
    1) The numbers 2-gypsum, 4-fluorite, 7-quartz, 14-glass look so alike to me, is there any difference in appearance in these four things that can allow us to distinguish from one another?
    I think you'd do best to compare and contrast the fracture and cleavage of each. But the gypsum will scratch with your nail and has a powdery/soft feel to the surface. Eliminate that one first.

    The glass will be the next to eliminate -hard, concoidal fracturing -get that one out of the way.

    Next would be the quartz, also hard & might be cofused with the flourite depending upon the sample you have. The quartz has a conchoidal fracture like the glass and the cleavage of the will be perfect in four directions.

    The fluorite, on the other hand, will have perfect cleavage and forms octahedrons but will fracture with some irregularity and is a bit more brittle thanthe quartz. Scratch them together. The fluorite will break apart a bit when pressed hard with the quartz or pressed hard into the quartz. The flourite also has a more vitreous or "silky" luster than the quartz.

    Quote Originally Posted by kingwinner
    2) The numbers 3-calcite, 6-orthoclase feldspar, 15-alabaster look exactly the same to me, is there any difference in appearance in these three things that can allow us to distinguish from one another?
    Eliminate the calcite first -it'll be the one with the most distinct cleavage since it has a "rhombic" cleavage, perfect in three directions. It'll have an almost cubic looking breaks (use the quartz to chip an edge of it if it doesn't). The alabaster can also have a perfect cleavage, but it'll be more vitreous or 'silky' looking than the calcite. Alabaster is softer than calcite as well, so scratch one sample with the other and see which one has the mark... it'll be the alabaster. The feldspar will be the hardest of the three in this lot and will scratch the glass -the other two won't. Your quartz will scratch the glass as well.

    Quote Originally Posted by kingwinner
    Please click the following image for the second set of minerals!
    http://www.geocities.com/asdfasdf23135/DSC00595.JPG
    3) Number 15 is called a "quartz crystal", how is it different from a "quartz mineral"?
    I dunno... it doesn't look like a quartz crystal form to me in the picture, but rest assured it will scratch the glass. The crystaline form of quartz can have six sides.

    Good luck! Let us know how it goes!


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