Initial Publication Date: June 28, 2005
Unknown #7
Download and view the crystal structure data
- Right click on Unknown_7.cmdf ( 19kB Dec16 09) to download the crystal structure to your computer. (This file was modified from a CIF file in the Crystal Structure Library provided in CrystalMaker).
- Start the CrystalMaker program.
- Choose the File > Open command, and select the file you just downloaded to view in CrystalMaker.
- Click on OK to generate the crystal structure for viewing. This structure is already given to you as a polyhedral model. You should see something like this...
Determine the identity of the unknown
Using your knowledge of crystallography and systematic mineralogy, and manipulating the downloaded structure in CrystalMaker, answer the following questions to deduce the identity of the unknown. Check your answers by clicking on the "show answer" tabs which appear with each question.
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Is this mineral a silicate or non-silicate? If silicate, what type?
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This is a phyllosilicate (sheet silicate).
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Based on the arrangement of tetrahedral and octahedral layers in this mineral, is this a clay, mica, or something else?
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What element occupies the the T-O-T units in this mineral?
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Mg, so the mineral is trioctahedral.
...so what mineral is this?
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Chlorite - (Mg, Fe)
3(Si,Al)
4O
10(OH)
2 dot (Mg,Fe)
3(OH)
6
Chlorite
Image courtesy of Amethyst Galleries. The structure is from Phillips et al. (1980) American Mineralogist 65:112-122
Chlorite is the only phyllosilicate with the T-O-T O T-O-T O layered arrangement.
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