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© 2012 Pearson Education, Inc.
Earth Science, 13e
Tarbuck & Lutgens
© 2012 Pearson Education, Inc.
Matter and MineralsEarth Science, 13e
Chapter 2
Stanley C. Hatfield
Southwestern Illinois College
© 2012 Pearson Education, Inc.
Minerals: the 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
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Composition and structure of minerals
Elements • Basic building blocks of minerals • Over 100 are known
Atoms• Smallest particles of matter • Have all the characteristics of an element
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Periodic table of the elements
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How atoms are constructed
Nucleus – central part of an atom that contains • Protons – positive electrical charges • Neutrons – neutral electrical charges
Energy levels, or shells • Surround nucleus • Contain electrons – negative electrical
charges
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Simplified view of the atom
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How 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
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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
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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
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Good crystals of the mineral pyrite
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Galena displays metallic luster
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Mohs scale of hardness
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Minerals
Physical properties of minerals • Fracture – random pattern of breakage• Specific gravity – mineral density• Other properties
• Taste• Smell• Elasticity• Malleability
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Conchoidal fracture
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Minerals
Physical properties of minerals • Other properties
• Feel• Magnetism• Double Refraction• Reaction to hydrochloric acid
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Minerals
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)
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Composition of continental crust
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Minerals
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 structures
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The silicate (SiO4)-4 molecule
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Minerals
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
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Hornblende – a member of the amphibole group
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Minerals
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
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Minerals
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
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Potassium feldspar
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Minerals
Mineral groups • Nonsilicate minerals
• Major groups• Oxides
• Sulfides
• Carbonates
• Halides
• Native elements
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Common nonsilicate mineral groups
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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
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Minerals
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
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An underground halite (salt) mine
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End of Chapter 2
