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Earth Science, 11e Minerals: Building Blocks of Rocks Chapter 2
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 Mineraloid - lacks an orderly internal structure
Elements Composition and structure of minerals Basic building blocks of minerals Over 100 are known Atoms Smallest particles of matter Have all the characteristics of an element
Periodic table of the Elements Figure 2.4
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
Simplified view of the atom Figure 2.5
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
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 Cleavage
The mineral quartz often exhibits good crystal form
Pyrite (fool s gold) displays metallic luster Figure 2.10
Mohs scale of hardness Figure 2.12
Three examples of perfect cleavage fluorite, halite, and calcite
Minerals Physical properties of minerals Fracture Specific gravity Other properties Taste Smell Elasticity Malleability
Conchoidal fracture Figure 2.15
Minerals Physical properties of minerals Other properties Feel Magnetism Double Refraction Reaction to hydrochloric acid
Minerals A few dozen minerals are called the rockforming minerals The eight elements that compose most rockforming 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)
Composition of continental crust Figure 2.16
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
The silicate (SiO 4 ) -4 molecule Figure 2.17
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
Hornblende a member of the amphibole group
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
Minerals 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 feldspar
Plagioclase feldspar
Minerals Mineral groups Rock-forming silicates Feldspars are the most plentiful mineral group Crystallize from molten material Nonsilicate minerals Major groups Oxides Sulfides
Minerals Mineral groups Nonsilicate minerals Major groups Sulfates Carbonates Native elements
Native Copper
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
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) mine
End of Chapter 2