Download Introduction to Earth Science: Minerals, Rocks, and the Rock Cycle and more Slides Earth science in PDF only on Docsity! Earth Science Mr. Butz Introduction to the Lithosphere: Minerals and Rocks I. Composition of the Lithosphere - the lithosphere is made up of soil, sand, mud and rock, which are all composed of minerals A. Minerals - a mineral is a naturally occurring, crystalline, inorganic substance with specific physical and chemical properties. 1. Naturally Occurring - a process by which a material is formed in or on the earth. 2. Crystalline - the atoms and molecules of a mineral are the same throughout, and are joined in a fixed position as a solid in a definite pattern. 3. Inorganic Substance - not living, or formed from a living thing. 4. Chemical Symbol - a chemical symbol or formula can be used to represent a mineral. B. Mineral Composition - Most minerals are composed of two or more elements. Oxygen is the most abundant element in the earth’s crust by both weight and volume. Silicon is the Earth Science Mr. Butz second most abundant element by weight. C. Mineral Structure - different minerals can possess different structures. Silicate containing minerals (Silicon and Oxygen) have a structure based on the silicon-oxygen tetrahedron. In this arrangement, four oxygen atoms surround one silicon atom. Earth Science Mr. Butz 5. Cleavage - is the tendency of a mineral to split along surfaces, or planes of weakness. Minerals that do not show cleavage are classified as fractured. 6. Specific Gravity - minerals can be identified by determining their relative density as compared to water. 7. Chemical Tests - The use of hydrochloric acid to see if a mineral bubbles, or taste tests can help identify a mineral like halite or quartz. Taste tests can be dangerous, because some minerals can be toxic. 8. Special Properties - some minerals possess special Earth Science Mr. Butz properties like magnetism (magnetite), luminescence (flourite), piezoelectricity (quartz). E. Relationship of Minerals to Rocks - nearly all rocks are composed of minerals 1. Monomineralic - these are rocks formed from only one mineral like rock salt (halite), and limestone (calcite). 2. Polymineralic - rocks composed of more than one mineral. Granite always contains quartz and feldspar, along with other minerals like mica and hornblende. II. Rocks - A rock is a naturally formed, solid material that makes up the earth’s crust. Rocks are classified on the basis of their origin into three main categories, Igneous, Sedimentary, and Metamorphic. A. Igneous Rocks - These type of rocks form from the cooling and solidification of liquid rock. 1. Igneous Rock Identification - Igneous rocks are classified by mainly their texture, color, and mineral composition (see reference tables). Earth Science Mr. Butz 2. Sedimentary Rocks - Rocks that form from the accumulation of sediments derived from preexisting rocks and/or organic material. a. Formation of Sedimentary Rocks - Lithification is the conversion of sediments into solid rock. Four main processes lithify sedimentary rock: Earth Science Mr. Butz 3. Metamorphic Rocks - these rocks form when rocks (parent rocks) undergo a change as a result of exposure to intense heat and pressure. 1. Recrystallization - as a result of intense heat and pressure, many rocks will form new crystals, without actually melting. 2. Foliation - this is a layered arrangement of crystals in metamorphic rock. The more intense the heat and pressure, the thicker the foliation. Earth Science Mr. Butz 3. Distorted Structure - many metamorphic rocks display a curving or folding of foliations as a result of exposure to intense pressures. Earth Science Mr. Butz 4. Increased Density - metamorphisized rocks often have a higher density as a result of being exposed to extreme pressures. 5. Contact Metamorphism - when magma (intrusive rock) comes into contact with rock beneath the earth’s surface, the heat metamorphisizes the surrounding rocks.
