3. January's birthstone 5. Most abundant group of minerals on the Earth 8. Hardest rock known to man. 9. yellow cousin of amethyst 10. The remnants of life that has turned to stone. 12. The study of the Earth. 13. February's birthstone Down 1. The art of cutting stones 2. Georgia's mineral 4. A hollow rock filled with crystals 6. A device used to polish stones that takes weeks and weeks of continual use. 7. The study of fossils 11. The second-most-abundant mineral in Earth's continental crust, after feldspar.