Earth Science, 11eMinerals: the building blocks of rocks Composition and structure of minerals Periodic table of the Elements How atoms are constructed Simplified view of the atomHow atoms are constructed How atoms are constructed Minerals The mineral quartz often exhibits good crystal formPyrite (fool’s gold) displays metallic lusterThree examples of perfect cleavage – fluorite, halite, and calciteMinerals Conchoidal fractureMinerals Minerals Composition of continental crustMinerals The silicate (SiO4)-4 moleculeMinerals Hornblende – a member of the amphibole groupMinerals Minerals Potassium feldspar Plagioclase feldsparMinerals Minerals Native CopperMinerals Minerals An underground halite (salt) mineEnd of Chapter 21© 2006 Pearson Prentice HallThis work is protected by United States copyright laws and is provided solely for the use of instructors in teaching their courses and assessing student learning. Dissemination or sale of any part of this work (including on the World Wide Web) will destroy the integrity of the work and is not permitted. The work and materials from it should never be made available to students except by instructors using the accompanying text in their classes. All recipients of this work are expected to abide by these restrictions and to honor the intended pedagogical purposes and the needs of other instructors who rely on these materials.Lecture Outlines PowerPointChapter 2Earth Science 11eTarbuck/LutgensEarth Science, 11eMinerals: Building Blocks of RocksChapter 2Minerals: the building blocks of rocks Definition of a mineral• Natural• Inorganic• Solid• Possess an orderly internal structure of atoms• Have a definite chemical compositionMineraloid - lacks an orderly internal structureComposition and structure of minerals Elements• Basic building blocks of minerals • Over 100 are knownAtoms• Smallest particles of matter• Have all the characteristics of an elementPeriodic table of the ElementsFigure 2.4How atoms are constructed Nucleus – central part of an atom that contains• Protons – positive electrical charges • Neutrons – neutral electrical chargesEnergy levels, or shells • Surround nucleus• Contain electrons – negative electrical charges2Simplified view of the atomFigure 2.5How atoms are constructed Atomic number is the number of protons in an atom's nucleus Bonding of atoms • Forms a compound with two or more elements • Ions are atoms that gain or lose electrons Isotopes • Have varying number of neutrons How atoms are constructed Isotopes • Have different mass numbers – the sum of the neutrons plus protons • Many isotopes are radioactive and emit energy and particles Minerals Physical properties of minerals •Crystal form•Luster•Color• Streak• Hardness• CleavageThe mineral quartz often exhibits good crystal formPyrite (fool’s gold) displays metallic lusterFigure 2.103Figure 2.12Mohs scaleof hardnessThree examples of perfect cleavage – fluorite, halite, and calciteMinerals Physical properties of minerals • Fracture• Specific gravity• Other properties•Taste•Smell• Elasticity• MalleabilityConchoidal fractureFigure 2.15Minerals Physical properties of minerals • Other properties• Feel• Magnetism• Double Refraction• Reaction to hydrochloric acidMinerals A few dozen minerals are called the rock-forming minerals • The eight elements that compose most rock-forming minerals are oxygen (O), silicon (Si), aluminum (Al), iron (Fe), calcium (Ca), sodium (Na), potassium (K), and magnesium (Mg) • Most abundant atoms in Earth's crust are oxygen (46.6% by weight) and silicon (27.7% by weight)4Composition of continental crustFigure 2.16Minerals Mineral groups • Rock-forming silicates• Most common mineral group • Contain the silicon-oxygen tetrahedron (molecule)• Four oxygen atoms surrounding a much smaller silicon atom• Combines with other atoms to form the various silicate structuresThe silicate (SiO4)-4moleculeFigure 2.17Minerals 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 Hornblende – a member of the amphibole groupMinerals 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 tetrahedra5Minerals Mineral groups • Rock-forming silicates• Groups based upon tetrahedral arrangement • Feldspars• Two types of feldspar are Orthoclase and Plagioclase• Quartz – three-dimensional network of tetrahedra Potassium feldsparPlagioclase feldsparMinerals Mineral groups • Rock-forming silicates• Feldspars are the most plentiful mineral group • Crystallize from molten material • Nonsilicate minerals • Major groups• Oxides• SulfidesMinerals Mineral groups • Nonsilicate minerals • Major groups•Sulfates• Carbonates• “Native” elementsNative Copper6Minerals 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 Minerals Mineral resources • Reserves are already identified deposits• Ores are useful metallic minerals that can be mined at a profit • Economic factors may change and influence a resource An underground halite (salt) mineEnd of Chapter
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