Quiz:

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Quiz

• List the four spheres of Earth which interact to
  compose the Earth system.
• Cell phones (are / are not) permitted to be used
  in class except for approved emergencies?
• Bonus What is my office number?

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What Is a Mineral?
January 23rd
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Minerals Building Blocks of Rocks

• Naturally Occurring
• Inorganic Solid
• Specific Chemical Composition
• with a Crystalline Structure

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Naturally Occurring, Inorganic

• Must be found in nature
• Diamond from mines of South Africa minerals
• Diamond created in lab in Texas not a mineral
• Inorganic solid
• ? Carbon without hydrogen (H)-bonds, inorganic
• Organic carbon as found in all living (or dead)
  things possesses H coal not minerals
• Calcite (CO3) secreted by organisms mineral

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What Are Minerals Made Of?

• Element fundamental component of matter
• Cannot be broken down into simpler particles
• 88 elements occur naturally in the crust but only
  8 elements make up 98 of crust
• oxygen (O), silicon (Si), aluminum (Al),
• iron (Fe), calcium (Ca), magnesium (Mg),
• potassium (K), and sodium (Na)

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The Basic Structure of Matter

• Minerals made up of atoms of specific elements in
  specific arrangements
• Nature of atoms crucial to forming minerals

SiO2
O
Si
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Atomic Structure

• Atoms composed of
• Protons (positive charge)
• and Neutrons (no charge)
• Surrounded by cloud of
• electrons (negative charge)

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How Do the Atoms Interact?

• Atoms interact via outermost electrons to form 3D
  structure of minerals
• Electron Sharing (Covalent bonds)
• Two atoms share electron(s) ? strong bonds

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How Do the Atoms Interact?

• Electron Transfer (Ionic bonds)
• Atom gains (or loses) electron to another atom
• Ions are now charged (positive or negative)
• Weaker but more common than Covalent

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Specific Chemical Composition

• A minerals chemical composition is fixed (never
  varies, like NaCl) or varies within defined
  limits
• Minerals are unique because of chemical
  composition and arrangement of atoms

Chemical Composition SiO2
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Chemical Composition K(Fe,Mg)3AlSi3O10(OH)2
varies within defined limits
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Crystal-line Structure

• Not liquids or gases
• Atoms that compose substance arranged in orderly,
  repeated three dimensional array

Cl
Na
NaCl Halite or table salt (rock salt)
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Quiz

• Which one is not a mineral
• Oil
• Quartz (SiO2)
• Halite (Rock Salt NaCl)

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How Do Minerals Grow?

• Atoms in the proper chemical proportions come
  together forming 3D structure
• As long as basic order is repeated ? crystal
• Boundaries are natural flat surfaces called
  crystal faces (external expression of structure)

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Perfect Development?

• All things need space and time

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How We Identify Crystals

• All minerals have physical and chemical
  properties that can be easily recognized
• Direct result of structure and composition

• Crystal Habit
• Cleavage
• Fracture
• Hardness
• Color

• Streak
• Luster

Effervescence in HCl
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More Physical Properties

• Cleavage
• Tendency to break along flat surfaces
• Governed by bond strength and internal 3D
  structure
• Stronger bonds, poor to no cleavage

Quartz
Calcite
Biotite Mica
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More Physical Properties

• Hardness (Scale 1-10)
• Dependent on strength of atomic bonds (ionic vs.
  covalent)
• Can be determined by scratching with materials of
  known hardness
• From talc (1) to diamond (10)

Quartz (hardness 7) scratches glass (hardness 5.5)
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More Physical Properties

• Luster
• Manner in which mineral reflects light
• Metallic, glassy, pearly, earthy, resinous, dull

Glassy luster
Metallic luster
Pearly luster
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Homework

• Read Chapter 2 of Text
• Pay careful attention to Focus (pg 26-27),
• Due Friday
• Type it or I wont accept it.
• 10 pts Review (pg. 42) 1, 2, 6, 9, 11
• 2 pts Discussion (pg 43) 5
• 5 pts Picture and description Name, Major,
  Hobbies, Career Goals, Favorite Cartoon

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Example
Insert REAL Picture Here

• Name T
• Major Geology
• Hobbies Collecting bling, defeating Rocky
  Balboa, pityin fools
• Goals College teacher
• Favorite saying Fool!