5 Minerals and Rocks

5 MINERALS AND ROCKS Minerals Mineral - a naturally occurring, inorganic solid with an orderly crystalline structure and a definite chemical composition. Silicate - a mineral that contains silicon and oxygen and usually more than one other element Sulfate - any mineral that is an anion contains the element sulfur. It is formed when mineral rich waters evaporate. Sulfide - any mineral that is a chemical compound and contains the element sulfur. It is formed with thermal or hot-water solutions. Oxide - minerals that contain oxygen and one or more elements, which are usually metals. Halide - minerals that contain a halogen ion and one or more other elements. Carbonate - minerals that contain the elements carbon, oxygen, and one or more elements other than metallic elements. Native Element - group of minerals that exist in a relatively pure form. Streak - color of a mineral in powder form. Luster - used to describe how light is reflected from the surface of a mineral. (e.g. metallic luster) Crystal Form - visible expressions of a mineral’s internal arrangement of atoms. The arrangement of the atoms controls the shape of the mineral. Cleavage - tendency of a mineral to break along flat and even surfaces. Fracture - tendency of a mineral to break uneven. Hardness - measure of the resistance of a mineral of being scratched. Igneous - rocks formed from the melting of magma; can be either intrusive or extrusive. Metamorphic - rocks formed under either heat or pressure (sometimes both) Sedimentary - rocks formed from sediments being compacted or cemented. Sediment - rock fragments that have been transported to a different location due to wind, water, or gravity. Chemical Sedimentary Rocks - sedimentary rocks formed from chemicals dissolved in water; included rock salt and travertine that are types of limestone. Organic Sedimentary Rocks - sedimentary rocks that are composed of the remains of living organisms. Includes fossils and coal. Intrusive - rock that forms below Earth’s surface; usually igneous rocks. Extrusive - rocks that form above Earth’s surface; usually igneous rocks. Magma - body of molten rock found at the depths of Earth. Lava - magma that reaches Earth’s surface. Rock Cycle - a model that illustrates the origin of the three basic rock types and the relations of Earth’s materials and the processes carried. Weathering - the disintegration and decomposition of rock at or near Earth’s surface due to rain, wind, ice, sunlight, and plants. Compaction - a process by which sedimentary rocks are squeezed together by the weight of overlying materials driving out the water. Cementation - solidification of sediments by the deposition of dissolved minerals in tiny spaces between sedimentary particles. Foliated - a metamorphic rock with a texture that gives the rock a banded or layered appearance. Non-foliated - a metamorphic rock that does not exhibit a banded or layered appearance. Clastic - sedimentary rocks that are composed of rock fragments cemented together. Deposition - the natural process of adding transported sediments to landform. Erosion - the transport of fragments of rock by forms of water or gravity. Lithification - the compaction and cementation of sediment into rock. Metamorphism - a solid state change in an existing rock due to high pressure or temperature that creates a metamorphic rock. Texture - the sizes, shapes, and positions of the grains in a rock. Igneous Rocks Igneous rocks are a product of magma- a hot liquid made of melted minerals- when it is cooled down and forms crystals. These types of rocks form underground (intrusive) or on Earth’s surface (extrusive) where mama usually cools down quickly. Sedimentary Rocks Sedimentary rocks are formed as a result of cementation and compaction of sediments. Sediments are pieces of rocks that have been broken down as a result of wind or water. Over time, sediments are cemented together to form layers within a sedimentary rock. Metamorphic Rocks Metamorphic rocks are formed as a result of heat and/or pressure. Heat can be derived from pressure (pushing your hands together very hard and feeling the heat), friction (rubbing your hands together to feel the heat) or radioactive decay (the process that gives us nuclear power that makes electricity). When heat and pressure is applied to rocks, they form larger crystal called metamorphic rocks. Rock Cycle The rock cycle consists of a group of changes from: 1. Igneous to sedimentary or metamorphic - The effect of weathering or erosion on igneous rocks results in the formation of sediments, which later form sedimentary rocks due to compaction and cementation. - When heat or pressure is applied to an igneous rock, it changes into a metamorphic rock over time. 2. Sedimentary to metamorphic or igneous - When heat or pressure is applied to a sedimentary rock, it changes into a metamorphic rock over time. - The effect metamorphism on sedimentary rocks formed metamorphic rocks. When further melted into magma and then cooled, the rock changes into igneous. 3. Metamorphic into sedimentary or igneous - The effect of weathering and erosion of metamorphic rocks is the formation of sediments. When these sediments are compacted and cemented, sedimentary rocks are formed. - When melted, metamorphic rocks change into magma, which when cooled down forms igneous rocks.