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Chapter 2 Lecture Earth Science Fourteenth Edition Matter and Minerals Jennifer Mangan James Madison University © 2015 Pearson Education, Inc. Minerals: Building Blocks of Rocks • Definition of a mineral – – – – – Natural Inorganic Solid Possess an orderly internal structure of atoms Have a definite chemical composition • Rock – any naturally occurring solid mass of mineral or mineral-like matter © 2015 Pearson Education, Inc. Rocks are Aggregates of Minerals © 2015 Pearson Education, Inc. Atoms: Building Blocks of Minerals • Atoms – Smallest particles of matter © 2015 Pearson Education, Inc. Atomic Structure • Nucleus – central part of an atom that contains – Protons – positive electrical charges – Neutrons – neutral electrical charges • Electron shells – Surround nucleus – Contain electrons – negative electrical charges © 2015 Pearson Education, Inc. Atomic Structure © 2015 Pearson Education, Inc. Atoms • Atomic number – Number of protons in an atom’s nucleus. • Ions – Positively or negatively charged atoms due to electron gain or loss © 2015 Pearson Education, Inc. Composition and Structure of Minerals • Elements – – – – Basic building blocks of minerals Over 100 are known Defined by their number of protons Groups of the same type of atoms © 2015 Pearson Education, Inc. Periodic table of the elements © 2015 Pearson Education, Inc. Atomic Bonding • Valence shell – An atom’s outermost shell • Octet rule – Atoms gain, lose, or share electrons until their valence shells have 8 electrons • Chemical bond – Transfer or sharing of electrons to achieve full valence shell © 2015 Pearson Education, Inc. Atomic Bonding • Ionic bond – Atoms bond together when oppositely charged ions attract © 2015 Pearson Education, Inc. Atomic Bonding • Covalent bond – Sharing of a pair of electrons between atoms © 2015 Pearson Education, Inc. Atomic Bonding • Metallic bond – Packed metal atoms have valence electrons free to move throughout the structure. © 2015 Pearson Education, Inc. Minerals • Physical properties of minerals – – – – – – Habit – common crystal shape Luster – appearance in reflected light Color Streak – color of mineral in powdered form Hardness – ability to resist scratching or abrasion Cleavage – tendency to break along planes of weak bonding © 2015 Pearson Education, Inc. Metallic Luster: Galena © 2015 Pearson Education, Inc. Color • Color can be unreliable due to variations. © 2015 Pearson Education, Inc. Streak © 2015 Pearson Education, Inc. Crystal Shape, or Habit: Pyrite © 2015 Pearson Education, Inc. Hardness: Mohs Scale © 2015 Pearson Education, Inc. Cleavage: Micas © 2015 Pearson Education, Inc. Minerals • Physical properties of minerals – Fracture – random pattern of breakage – Specific gravity – mineral density – Tenacity – resistance to cutting, breaking, bending, and deformation © 2015 Pearson Education, Inc. Conchoidal fracture © 2015 Pearson Education, Inc. Minerals • Other properties – – – – – – – – Taste Smell Elasticity Malleability Double refraction Magnetism Feel Reaction with hydrochloric acid © 2015 Pearson Education, Inc. Mineral Groups • Rock-forming minerals – Only a few dozen – Most abundant atoms in Earth’s crust are oxygen (46.6% by weight) and silicon (27.7% by weight) © 2015 Pearson Education, Inc. Mineral Groups • Eight elements compose most rock-forming minerals: – – – – – – – – oxygen (O), silicon (Si), aluminum (Al) iron (Fe) calcium (Ca) sodium (Na) potassium (K) magnesium (Mg) © 2015 Pearson Education, Inc. Composition of Continental Crust © 2015 Pearson Education, Inc. Mineral Groups • Rock-forming silicates – Most common mineral group – Contain the silicon-oxygen tetrahedron • Four oxygen atoms surrounding a much smaller silicon atom • Combines with other atoms to form the various silicate structures © 2015 Pearson Education, Inc. Mineral Groups • Rock-forming silicates – Groups based upon tetrahedral arrangement • Olivine – independent tetrahedra • Pyroxene group – tetrahedra are arranged in chains • Amphibole group – tetrahedra are arranged in double chains © 2015 Pearson Education, Inc. Hornblende: An Amphibole © 2015 Pearson Education, Inc. Mineral Groups • Rock-forming silicates – Groups based upon tetrahedral arrangement • Micas – tetrahedra are arranged in sheets – Two types of mica are biotite (dark) and muscovite (light) • Feldspars – Three-dimensional network of tetrahedra © 2015 Pearson Education, Inc. Mineral Groups • Rock-forming silicates – Groups based upon tetrahedral arrangement • Feldspars – most abundant group of minerals in Earth’s crust • Quartz – three-dimensional network of tetrahedra © 2015 Pearson Education, Inc. Potassium feldspar © 2015 Pearson Education, Inc. Rose Quartz © 2015 Pearson Education, Inc. Mineral Groups • Nonsilicate minerals – major groups – – – – – Oxides Sulfides Carbonates Halides Native elements © 2015 Pearson Education, Inc. Common Nonsilicate Mineral Groups © 2015 Pearson Education, Inc. Minerals • Mineral groups – Nonsilicate minerals • Carbonates – A major rock-forming group – Found in the rocks limestone and marble • Halite and gypsum are found in sedimentary rocks • Many have economic value © 2015 Pearson Education, Inc. Natural Resources • Renewable – Can be replenished in relatively short time spans • Corn, wind, water, etc. • Nonrenewable – Earth has fixed quantities • Oil, aluminum, natural gas, coal © 2015 Pearson Education, Inc. Natural Resources • Mineral resources – Mineral resources are occurrences of useful minerals that will eventually be extracted – Ore deposits are concentrations of metallic minerals that can be mined at a profit – Economic factors may change and influence a resource © 2015 Pearson Education, Inc. Copper Mining © 2015 Pearson Education, Inc.