| 1. | Staurolite is a common metamorphic intermediate-grade index mineral.
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| 2. | Minerals that are characteristic for a certain metamorphic grade are called index minerals.
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| 3. | Often they are named for the most characteristic index mineral of the zone.
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| 4. | Many index minerals have complicated chemical compositions.
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| 5. | Index minerals are used in geology to determine the degree of metamorphism a rock has experienced.
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| 6. | Whether a certain index mineral occurs is also dependent on the composition of the rock itself.
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| 7. | Lawsonite is a significant metamorphic mineral as it can be used as an index mineral for high pressure conditions.
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| 8. | Every first appearance of an index mineral was taken by Barrow as the beginning of a new metamorphic zone.
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| 9. | Very typical index minerals are the polymorphs of aluminosilicate ( Al 2 SiO 5, all are nesosilicates ).
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| 10. | These minerals, known as index minerals, include sillimanite, kyanite, staurolite, andalusite, and some garnet.
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