| 1. | The latter property is particularly common in gem-quality corundum.
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| 2. | All other hues of the gem species corundum are called sapphire.
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| 3. | In 1900, mining operations began by the Canada Corundum Company.
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| 4. | Topaz and Corundum are pretty hard stones in their own right.
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| 5. | Other varieties of gem-quality corundum are called sapphires.
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| 6. | Some are made entirely of faceted sapphire ( corundum ).
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| 7. | It also occurs as a hydrothermal alteration product of corundum and nepheline.
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| 8. | In 1876, the mountain was discovered as a source for Corundum.
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| 9. | In 2004, over 2 kilograms of corundum were collected.
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| 10. | For those you'd need diamond or corundum blades.
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