Matter and Minerals

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Matter and Minerals
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What is a mineral?????

• Minerals must meet the following criteria to be
  considered minreals
• Naturally occurring
• Inorganic
• Have an orderly crystalline structure

nutrition
Earth Resource
Constituent of Rocks
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What makes minerals different colors from one
another?

• Chemical composition
• Chemical structure

Calcite CaCO3
Rhodochrosite MnCO3
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Minerals

• Chemical composition every mineral has a defined
  chemical formula, though some have ranges of
  compositions
• Gold Au
• Corundum Al2O3
• Plagioclase Feldspar CaAl2Si2O8-NaAlSi3O8

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AHHHHHHHHHHHHHHH!!!!! CHEMISTRY!!!!!!!!!!!!!!!!!

• Chemical structure controlled by the elements
  and the types of bonds that hold minerals
  together Elements every distinct element has a
  specific number of protons and an equal number of
  electrons when at stable state number of
  neutrons varies (creating isotopes)
• Consider bonds

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• Bonds?

Nope
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Chemical (Not Barry) Bonds

• Bonding in minerals To make a chemical compound
  the atoms must be bound together by bonds
• Bonds generally involve sharing or exchanging
  electron, or the smaller attractions of other
  molecular forces
• Different types of bonds produce different
  physical characteristics

Not Shown Metallic van der Waals
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• The type of bonds and geometry of bonds control
  the structure on the minerals

Fluorite CaF2
Halite NaCl
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• Structure of minerals controls appearance of
  minerals
• How they grow Crystal Habit

Halite NaCl
Fluorite CaF2
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• Structure of minerals controls appearance of
  minerals
• How they break Cleavage (everyone laugh)

Halite NaCl
Fluorite CaF2
3 Directions of Cleavage
4 Directions of Cleavage
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Minerals

• How they grow Crystal Habit
• Silicon is, by far the most abundant element in
  the crust, and most important rock forming
  minerals are silicates
• Silicates are constructed of various arrangements
  of silcon tetrahedra (a silicon surrounded by
  four oxygens)

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• Tetrahedra are linked at their corners in
  different arrangements

Single Chains
Isolated
Double Chains
Paired
Rings
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Distinguishing between minerals

• Luster
• Crystal Form
• Cleavage
• Hardness
• Other distinguishing properties
• Reacts with acid
• Magnetic
• Smell
• Taste
• Striations

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Minerals

• Luster and Color
• Luster (metallic or non-metallic)
• Color (can be misleading e.g. Potassium
  Feldspar)

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Minerals

• Cleavage and Hardness
• Cleavage breaks on smooth, flat planes across
  week bonds in atomic structure
• Hardness

corundum
Talc
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So what controls where minerals form!!!!

• What elements were available at the time of
  formation
• Physical conditions during formation
• Temperature
• Pressure
• Most minerals in the crust formed in the interior
  of the earth where they were stable at higher P
  and T
• Most minerals are not stable at surface P and T
• So, why havent all of these minerals been
  transformed in to minerals that are stable at the
  surface?

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So, why havent all of these minerals been
transformed in to minerals that are stable at the
surface?

• Kinetics!
• These reactions take a lot of time to happen,
  especially when the temperature is low (e.g. the
  earths surface)
• Water helps things go faster
• So water is important in the chemical breakdown
  of minerals chemical weathering
• Remember the hydrologic cycle!!!!!!

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Building blocks of Building Blocks (Granite)
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Silicate Minerals most abundant mineral group

• Silicon-oxygen tetrahedra
• Contains Silicon and oxygen in basic structure
  2 very important and abundant elements in rocks

Basic chemical structure
asbestos
quartz
mica
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Chemical (Not Barry) Bonds
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Ferromagnesian (Dark) Silicates

• Usually formed at high T and P

pyroxene
Rock with hornblende
olivine
AND LOTS OF OTHERS!!!!!!!!!
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Nonferromagnesian (light) silicates

• Formed at high P and T, but the lack of iron
  makes these minerals light in color.

Muscovite (similar to biotite but no iron)
Quartz (pure Silica and oxygen)
Feldspar (as we saw in granite)
AND LOTS OF OTHERS!!!!!!!!!
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Important Nonsilicate minerals

• Halides
• Carbonates
• Hydroxides
• phosphates

• Oxides
• Sulfides
• Sulfates
• Native elements

halite
Hematite
calcite
pyrite
bauxite
gypsum
turquoise
gold