Rocks Crosswords

3. Microcrystalline quartz
7. See the picture on the back
8. A chemical sedimentary rock with fine to coarsely crystalline texture and composed of halite
12. An igneous rock that owes its glassy texture to rapid cooling
14. A metamorphic rock with fine to coarse grained texture and is composed of calcite and dolomite
15. Forms when lava or magma cools and crystallizes, and includes obsidian and diorite
16. common in shallow water environments
18. An oxide that is commonly used as iron ore
19. See the picture on the back
20. An igneous, spongy-looking rock that form due to trapped gas bubbles

1. An ultrabasic rock that often holds diamonds
2. A clastic sedimentary rock with fine texture and composed of quartz and clay
4. See the picture on the back
5. A sulfide that contains lead
6. Used in countertops and floors
9. Rocks that are dark-colored and have lower silica contents
10. A feldspar that doesn't contain sodium
11. A hard, often light-covered rock formed by the metaporphism of quartz-rich sandstone
13. See the picture on the back
17. Rocks that are light-colored and have a high silica contents