© 2006 Pearson Prentice Hall Lecture Outlines PowerPoint Chapter 2 Earth Science 11e Tarbuck/Lutgens.

© 2006 Pearson Prentice Hall

Lecture Outlines PowerPoint

Chapter 2

Earth Science 11e

Tarbuck/Lutgens

Minerals: Building Blocks of Rocks

Chapter 2

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 • Basic building blocks of minerals • Over 100 are known

Atoms• Smallest particles of matter • Have all the characteristics of an element

Figure 2.4

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

Figure 2.5

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

Isotopes • Have different mass numbers – the sum of

the neutrons plus protons • Many isotopes are radioactive and emit

energy and particles

Physical properties of minerals • Crystal form• Luster• Color• Streak• Hardness• Cleavage

Figure 2.10

Figure 2.12

Mohs scale of hardness

Physical properties of minerals • Fracture• Specific gravity• Other properties

Taste Smell Elasticity Malleability

Figure 2.15

Physical properties of minerals • Other properties

Feel Magnetism Double Refraction Reaction to hydrochloric acid

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)

Figure 2.16

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

Figure 2.17

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

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

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

Mineral groups • Rock-forming silicates

Feldspars are the most plentiful mineral group Crystallize from molten material

• Nonsilicate minerals Major groups

• Oxides• Sulfides

Mineral groups • Nonsilicate minerals

Major groups• Sulfates• Carbonates• “Native” elements

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

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