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MINERALS AND SYNTHETIC COMPOUNDS, AmXn, IN WHICH X
ATOMS ARE |
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CLOSE PACKED AND A ATOMS OCCUPY OCTAHEDRAL INTERSTICES |
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Bayerite |
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click here to see a key to this data bar
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octa |
1/3 |
hcp |
layer |
3
edges |
A-
6c, X- 2c/hcp |
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structure |
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In the bayerite layer
structure X atoms are HCP and A atoms occupy 2/3 of the |
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octahedral interstices of every other layer for
an overall occupancy rate of 1/3. An |
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occupied bayerite layer is isostructural with a
corundum layer. |
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Ex.
a-Al(OH)3
( aluminum hydroxide, bayerite ) ( Al - A , OH - X ) |
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Crystal lattice |
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Note how the hexagonal
nets of the AX6 coordinated groups in each occupied |
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layer eclipse each other in HCP fashion. |
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Figure 92 -
Bayerite lattice structure |
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click image to enlarge |
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Polyhedral framework |
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linking surfaces |
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Figure 93 -
Bayerite polyhedral |
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framework model |
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3
edges |
click image to enlarge |
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Cleavage |
Crystal habit |
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(100) |
hexagonal, tabular |
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Isostructural minerals/compounds |
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CrCl3 (low), CrBr3, BiI3,
AsI3,
SbI3,
FeCl3 |
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Page
60 - Structure matters - Bayerite |
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