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Chapter One:  Building Blocks of Rocks

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Minerals vs Rocks

A. Mineral definition

Naturally occurring

Inorganic

Solid

Have a definite chemical structure

B. Nearly 4000 known minerals

C. Rocks are aggregates ( mixtures) of minerals

 

Composition and structure of minerals

Elements

Basic building blocks of minerals

Over 100 known

Atoms

Smallest particles of matter

Have all the characteristics of an element

 

How atoms are constructed

Nucleus, which contains

Protons - positive electrical charges

Neutrons - neutral electrical charges

Energy levels, or shells

Surround nucleus

Contain electrons - negative electrical charges

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

Have different mass numbers - the sum of the neutrons plus protons

Many isotopes are radioactive and emit energy and particles

 

Minerals

Properties of minerals

Crystal form

Luster

Color

Streak

Hardness

Cleavage

Fracture

Specific gravity

Other

Taste

Smell

Elasticity

Malleability

Feel

Magnetism

Double refraction

Reaction to hydrochloric

 

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 percent by weight )

.Silicon ( 27.7 percent by weight )

 

Mineral groups

Silicate minerals

Most common mineral group

Contain silicon - oxygen tetrahedron

Groups based upon tetrahedron arrangement

Olivine - independent tetrahedron

Pyroxene group - tetrahedron are arranged in chains

Amphibole group - tetrahedron are arranged in double chains

Micas

Tetrahedron are arranged in sheets

Two types of mica

Biotite ( dark ) and

Muscovite ( light )

 

Feldspar

Feldspars

a. Three - dimensional network of tetrahedron

b. Two types of feldspars

1. Orthoclase and

2. Plagioclase

Quartz - three dimensional network of tetrahedron

Feldspars are the most plentiful mineral group

Crystallize from molten material

 

Nonsilicate minerals

A. Major groups

1. Oxides

2. Sulfides

3. Sulfates

4. Halides

5. Carbonates

6. " Natives " elements

B. Carbonates

1. A major rock - forming group

2. Found in the rocks limestone and marble

C. Halite and gypsum are found in sedimentary rocks

D. Many have economic value

 

Minerals resources

1. Reserves are already identified deposits

2. Ores are useful metallic minerals that can be mined at a profit

3. Economic factors may change and influence a resource

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