| 11. | Xenoliths that originated in the Earth's crust include rich metamorphic rocks and felsic intrusive rocks.
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| 12. | The sapphire bearing Yogo dike is a dark gray to green intrusive rock known as a lamprophyre.
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| 13. | Its colouration is from weathering of plagioclase, which comprises more than 50 % of the intrusive rock.
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| 14. | These may be named formally or informally as a class of intrusive rock or within a larger igneous association.
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| 15. | These overlie Late Cretaceous and younger intrusive rocks that form the glaciated mountain ridge on which Crevasse Crag lies.
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| 16. | When erosion removes the overlying rock material, these intrusive rocks are exposed and the pressure on them is released.
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| 17. | Granophyres typically are intrusive rocks that crystallized at shallow depths, and many have compositions similar to those of granites.
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| 18. | The second group of younger Early Paleoproterozoic igneous intrusive rocks is quite different in style, age, and significance.
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| 19. | Aenigmatite is primarily found in peralkaline volcanic rocks, pegmatites, and granites as well as silica-poor intrusive rocks.
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| 20. | This makes it the oldest recognised intrusive rock on the Earth, containing the oldest known igneous textures and mineral assemblages.
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