The document discusses different types of rocks including igneous, sedimentary, and metamorphic rocks. Igneous rocks such as granite and obsidian are formed from cooled lava. Sedimentary rocks form in layers from compressed sediments. Metamorphic rocks are formed from extreme heat or pressure acting on sedimentary or igneous rocks. Gemstones are rare rocks that are used in jewelry.
6. Metamorphic rock Metamorphic rock is formed when extreme pressure or heat is applied to sedimentary or igneous rock . The crystalline shape presses together.
37. Bibliography Lambert, David. Rocks and Minerals New York: Franklin Watts, 1986. Print. Morris, Neil. Rocks and Minerals, . New York: Crabtree Publishing Company, 1998. Print. Pellant, Chris . The Best Book of Fossils Rocks and Minerals. New York: King Fisher, 2000. Print. Walker, Sally. Rocks . Minneapolis, MN: Lerner Publications Company, 1998. Print. Images from Google Images