A few gemstones form in the mantle, but all gems are mined in the crust. The crust is made up of three kinds of rock, known in geology as igneous, metamorphic and sedimentary rock. If the magmatic mass cools slowly in the crust, it can crystallize and form minerals. Here are the gemstones included in this fun excavation game.
1. Emerald
2. Diamond
3. Amethyst
4. Ruby
5. Sapphire
6. Aquamarine
7. Citrine
8. Zircon
9. Garnet
10. Topaz
11. Tourmaline