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Across 1. A low density extusive rock used as an abrasive 5. Type of texture that extrusive rocks have. 7. One use for granite, these are made from granite. 8. Igneous rocks high in iron 11. The most abundant intrusive rock on earth. 12. A fine grained extrusive rock with a mineral composition similar to granite. 13. Melted rock found beneath the ground 15. What we call igneous rocks formed from cooling magma. 16. The Latin word for "fire" 17. A black glassy igneous rock used by ancients to make sharp tools. 19. When lava cools so quickly that no crystal structure develops. 20. Igneous rocks that have a high silicate content

Down 2. Type of textrue found in granite. 3. Melted rock found above the earth's crust 4. Heated obsidian, used in gardening 6. What we call igneous rocks formed from cooling lava. 7. One of three ways to classify igneous rocks 9. One of three ways to classify igneous rocks 10. A mixture of minerals and possibly other materials 14. One of three ways to classify igneous rocks 18. A mafic rock produced when lava erupts on the ocean floor.