Across
- 4. used in pencils
- 9. fossils that form when mud buries a plant or animal and quickly hardens
- 10. paleontologists are scientists who study _______
- 12. hardest substance of all
- 14. scientist that studies minerals
- 16. "mud ball"
- 19. durable artificial rock
- 20. rarest gemstone
- 21. radioactive metal
- 24. metal liquid at room temperature
- 25. often used to make chalkboards
Down
- 1. rare minerals that have not yet been polished
- 2. plant and animal remains that have turned to stone are _________ fossils
- 3. underground spring that shoots up boiling water and steam
- 5. lightweight, rustproof metal
- 6. decaying plant and animal material in the soil
- 7. scientist who studies the structure of the earth
- 8. most fossils were probably formed during the ___________
- 11. smells like mud when wet
- 13. molten rock in the earth's mantle
- 15. person who explores caves
- 17. most useful metal
- 18. best conductor of electricity
- 19. a type of weathering
- 22. oil in its natural state
- 23. solid minerals