| 21. | These include the amphibole, biotite, feldspar and zircon.
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| 22. | The metal is present in the gems called zircons.
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| 23. | Both research teams dated the zircon grains by analyzing their isotopes of uranium.
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| 24. | Other orthosilicates include zircon, staurolite, and topaz.
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| 25. | The crystal structure of zircon is tetragonal crystal system.
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| 26. | The most abundant gem in Ratanakiri is blue zircon.
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| 27. | The sands on the island contain rutile and zircon.
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| 28. | Also contained is zircon, fluorite, and allanite.
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| 29. | Much less common than colorless zircon is colorless scheelite.
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| 30. | He is known for his investigations of mannitol and his analyses of zircon.
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