1001 Space Earth Earth Rocks and Minerals Landscape Sea Weather and Climate Natural Disasters Resources Nature History Human World Science and Technology

Choose a Page:Are all minerals valuable?How do geologists find out about t...How do geologists study minerals?How hard are minerals?Why do some rocks form in layers?Why do minerals form shapes?How are igneous rocks made?How are metamorphic rocks made?What are fossils?What is hard rock geology?How do geologists date rocks?What is soft rock geology?*What are gems?*What is a mineral? What are gems? Gems are stones found in the Earth's crust, used in jewellery. Most are mineral crystals. Diamond is made from carbon. Sapphire is made from corundum. Opal is a gem made from silica, which does not form a crystal. A diamond   Previous: Back Book: 1001 Section: Earth Chapter: Rocks and Minerals