| 21. | It was the first gemmological laboratory to offer testing for possible Beryllium diffusion in corundum.
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| 22. | They are formed in the corundum structure ( ?-Al 2 O 3 ).
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| 23. | What did you use, diamond-tipped drill bits, or maybe just corundum?
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| 24. | Phosphoric acid with bases will separate out as quartz; excess of alumina crystallizes as corundum.
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| 25. | The basic structure of corundum is identical to gibbsite except the hydroxides are replaced by oxygen.
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| 26. | In an Austrian occurrence near Kloch, melilite, mayenite, wollastonite, kalsilite and corundum are found.
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| 27. | This facies is normative in quartz ( oversaturated in SiO 2 ) and in corundum ( peraluminous ).
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| 28. | In June 2014, Gemfields held an inaugural ruby and corundum auction in Singapore from its Mozambique operations.
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| 29. | Likewise, the only difference between ruby and sapphire is the type of impurities present in a corundum crystal.
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| 30. | The most common form of crystalline aluminium oxide is known as corundum, which is the thermodynamically stable form.
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