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Science Vocabulary: Rocks and Minerals The Rocks and Minerals unit test will be Wednesday, November 2, 2016. These terms will appear on the unit test. 1. Lithosphere: the outer solid part of the Earth that includes the crust and the upper-most mantle (Think “l” for “land”; Lithosphere = land) 2. Mineral: a natural, solid, non-living material with particles arranged in a repeating pattern 3. Streak: a mineral property to describe the color of the powder left behind when the mineral is rubbed on a rough surface 4. Luster: a mineral property to describe the way the surface of a mineral reflects light 5. Hardness: a mineral property that describes how well a mineral resists scratching 6. Rock: a natural, solid object made up of one or more minerals 7. Igneous rock: a type of rock that forms when magma or lava cools and hardens (Notes: Think about what happens when something ignites; it sets on fire, right? Well, igneous rocks form from rock that was ignited deep within Earth. It started as magma or lava (molten rock) and then it cooled into a solid to become a rock.) 8. Sedimentary rock: a type of rock formed by layers of sediments that were squeezed and stuck together over a long period of time (Notes: Think about a sandwich. A sandwich is made of layers of materials placed one on top of the other. Some of you have even taken a sandwich and smashed it together, making it thinner and tighter. Well, sedimentary rock is just like a sandwich that has been squeezed and stuck together!) 9. Metamorphic rock: a type of rock formed when sedimentary or igneous rocks change due to pressure or heat without melting 10. Rock cycle: the slow, never-ending process of rock changes (Notes: Think about a bicycle. Now think about a cycle as something that goes around in a circle. The rock cycle is a circle of rocks that change from one type to another.) 11. Organic: having to do with or coming from living things Science Notes: Rocks and Minerals Minerals In order to be classified as a mineral, a material must be non-living, natural, and solid with particles arranged in a repeating pattern (this is called its crystal form). Minerals are made of elements (remember, elements are pure substances that cannot be broken down further.) Minerals form at or near Earth’s surface, in Earth’s mantle, and/or in mineral-rich water. Minerals can be identified based on their individual properties. Properties of minerals: 1. Streak: color of powder left behind when a mineral is rubbed against a rough surface 2. Luster: describes the way the surface of the mineral reflects light (metallic/nonmetallic) 3. Hardness: the mineral’s ability to resist being scratched. Mohs’ hardness scale (1-10) is used to compare the hardness of an unknown mineral to a known mineral. The higher the number, the harder the mineral. A mineral with a higher number can scratch a mineral with a lower number. We use minerals everyday in everything from pencils to jewelry to food. Types of Rocks A rock is a material made up of one or more minerals. Most rocks are made of mixtures of materials. Rocks form in different ways and are classified based on how they are formed. There are three types of rocks: 1. Igneous rocks are formed from magma or lava that has cooled and hardened. There are intrusive and extrusive igneous rocks. Intrusive rocks cooled very slowly beneath Earth’s surface and have large crystals. Extrusive rocks cooled very quickly above Earth’s surface and have very small or no crystals. Examples of igneous rock include granite, basalt, pumice, and obsidian. 2. Sedimentary rocks are formed over time from layers of sediment that have been squeezed (compacted) and stuck together (cemented). ALMOST ALL FOSSILS ARE FOUND IN SEDIMENTARY ROCK! Examples of sedimentary rock include conglomerate, limestone, sandstone, and shale. 3. Metamorphic rocks are formed from any of the three types of rocks that have been changed within the Earth due to tremendous heat and/or pressure. Examples of metamorphic rock include marble, gneiss, slate, and schist. How Rocks Change – The Rock Cycle Rocks are in a constant state of change, but most changes happen over a long period of time (possibly thousands of years). Rocks change into igneous rocks when they have been melted into magma or lava and then have cooled and hardened. Rocks change into sedimentary rocks when they have been weathered (broken down), eroded (moved to another location), and deposited (dropped off) in a new location at which point the sediment becomes compacted (squeezed) and cemented (stuck together). Rocks change into metamorphic rocks when they have been exposed to a great amount of heat and/or pressure while still within the Earth.