rocks minerals 06

Rocks and Minerals
• Atoms, Elements, Isotopes, Ions, and
Compounds
• Minerals–General
• Types of Minerals
• Rocks


Minerals- the building blocks
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Atomic Structure
Elements and Isotopes
Ions
Compounds


Rocks and Minerals
• Minerals Defined
• Identifying Characteristics of Minerals
• Other Physical Properties of Minerals


Halite Crystal

Source: Photograph © The McGraw-Hill Companies, Inc./Bob Coyle, photographer.

Galena

Source: Photograph © The McGraw-Hill Companies, Inc./Doug Sherman, photographer.


Fluorite

Source: Photograph © The McGraw-Hill Companies, Inc./Doug Sherman, photographer.


Halite

Source: Photograph © The McGraw-Hill Companies, Inc./Doug Sherman, photographer.


Definition of a Mineral
“A naturally occurring, inorganic, solid
element or compound with a definite
chemical composition and a regular
internal crystal structure.”


Mineral Characteristics
• Chemical composition
– Diamond = graphite (both are pure carbon)

• Crystal structure
– Diamond ≠ graphite

Cubic Structure of Halite

Source: Photograph © The McGraw-Hill Companies, Inc./Bob Coyle, photographer.


Mineral Properties
• Hardness (Mohs hardness scale)
– See appendix C

• Cleavage (how it breaks- atomic scale)
• Luster- the surface ‘sheen’
• Color is not a good property for i.d.
– Corundum (Al2O3)


Minerals: two groups
• Silicates (Si + O ± other elements)
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All built with ‘silicon tetrahedra’
4 O atoms, 1 Si atom, 4- charge
Quartz, feldspars
Olivine (peridot) ferromagnesian (Fe, Mg)
Asbestos

Micas
Clays (tropical weathering)



Minerals: non-silicates
• Nonsilicates

Example

– Carbonates (CO3):
calcite
– Sulfates (SO4):
gypsum
– Sulfides (metal + S):
pyrite
– Oxides (metal + O):
hematite
– Hydroxides (metal + OH):
gibbsite
– Halides (metal + halide): salt (halite)
– Native elements
Au, Ag, Pt, Cu, C


Rocks
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The Rock Cycle
Igneous Rocks
Sediments and Sedimentary Rocks
Metamorphic Rocks
The Rock Cycle Revisited


Definition of a Rock
• A solid, cohesive aggregate of one or
more minerals or mineral materials
• Important for construction
• Geologic history


The Rock Cycle
• Earth as a constantly changing system
• Plate tectonics
• 3 types of rocks on Earth
– Igneous
– Sedimentary
– Metamorphic



The Rock Cycle
• Igneous Rocks
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Formed by the crystallization of magma
Usually made up of silicate minerals
Plutonic: solidified inside Earth (granite)
Volcanic: solidified on Earths surface (lava)


Granite, a Plutonic
Rock

Source: Courtesy of Carla W. Montgomery.


Obsidian,
Volcanic
Glass

Source: Photograph © The McGraw-Hill Companies, Inc./Bob Coyle, photographer.


Basalt, a Volcanic
Rock

Source:Courtesy of Carla W. Montgomery.


Porphyry, an
Igneous Rock

Source: Photograph © The McGraw-Hill Companies, Inc./Bob Coyle, photographer.


The Rock Cycle
• Sedimentary Rocks
– Chemical precipitation
• Limestone (carbonate), chert

– Clastic sedimentation
• Sandstone, shale, conglomerate


Limestone

Source: Photograph by I.J. W itkind, USGS Photo Library, Denver, CO.