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extrusive rock |
Also found in: Wikipedia, Hutchinson | 0.02 sec. |
extrusive rockAny igneous rock derived from magma that is poured out or ejected at the Earth's surface. Extrusive rocks are usually distinguished from intrusive rocks on the basis of their texture and mineral composition. Lava flows and pyroclastic debris (fragmented volcanic material) are extrusive; they are commonly glassy (e.g., obsidian) or finely crystalline (e.g., basalts and felsites). extrusive rock [ik′strü·siv ′räk] (geology) How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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| Redton initially focused on the area because it displayed a concentration of high gold values that corresponded with alkali intrusive and extrusive rocks. Geologically, the project area is a 15 million year old volcanic eruptive center dominated by a bi-modal suite of flow domes, dikes, and extrusive rocks that were intensively and extensively altered and mineralized by a hydrothermal system of the same age. The property covers a sequence of intrusive and extrusive rocks that are host to a number of known occurrences of nickel, copper, PGM's and gold. |
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